国立感染症研究所

98th Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (September 7, 2022) Material 1

 

Evaluation of the latest infectious status, etc.

Overview of infection status

  • The number of new cases of infection nationwide (by date of report) was approximately 681 per 100,000 in the last week, steadily decreasing at a ratio of this week to last week of 0.69. However, nationwide the level of infections remains higher than the peak in February this year, and the decrease in the number of infections has slowed down in some regions. Attention should be paid to the impact of the re-opening of schools after the summer break on the infection status.
  • With the decreasing number of new cases of infection, the number of patients receiving treatment is also decreasing. In addition, the use rate of beds is showing a downward trend, though it is still at a high level nationwide.
    The medical care provision system still suffers from the burden, not only of COVID-19, but also general medical services, but the status has improved.
    The number of severe patients has turned to show a decreasing trend, and although the number of deaths has stopped to increase, it is remaining high.

    Effective reproduction number: On a national basis, the most recent number is 0.93 (as of August 21), while the figure stands at 0.92 both in the Tokyo metropolitan and Kansai areas.

Local trends

* The value for new cases of infection is the number of persons per 100,000 among the total number for the latest week, based on the reporting dates.

  1. Hokkaido

    The number of new cases of infection was approximately 644 (approximately 623 in Sapporo City), with a ratio to the previous week of 0.88. Infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 30%.

  2. North Kanto

    In Ibaraki, Tochigi, and Gunma, the numbers of new cases of infection were roughly 559, 524, and 571, with ratios to the previous week of 0.68, 0.79, and 0.75, respectively. In Ibaraki, Tochigi, and Gunma, new cases of infection were mainly in their 30s or younger. The use rates of beds are slightly more than 50% in Ibaraki and slightly more than 40% in Tochigi and Gunma

  3. Tokyo metropolitan area (Tokyo and 3 neighboring prefectures)

    The number of new cases of infection in Tokyo was approximately 579, with a ratio to the previous week of 0.66. Infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 40%, and the use rate of beds for severe cases is slightly less than 30%. In Saitama, Chiba, and Kanagawa, the numbers of new cases of infection were approximately 557, 542, and 441, with ratios to the previous week of 0.73, 0.75, and 0.71, respectively. The use rates of beds are slightly more than 50% in Saitama and Kanagawa and slightly less than 50% in Chiba.

  4. Chukyo/Tokai

    The number of new cases of infection in Aichi was approximately 800, with a ratio to the previous week of 0.71. Infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 80%. In Gifu, Shizuoka, and Mie, the numbers of new cases of infection were approximately 795, 659, and 824, with ratios to the previous week of 0.73, 0.68, and 0.70, respectively. The use rates of beds are slightly less than 50% in Gifu, approximately 50% in Shizuoka, and slightly more than 50% in Mie.

  5. Kansai area

    The number of new cases of infection in Osaka was approximately 757, with a ratio to the previous week of 0.66. Infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 50%, while the use rate of beds for severe cases is approximately 10%. In Shiga, Kyoto, Hyogo, Nara, and Wakayama, the numbers of new cases of infection were about 779, 774, 758, 700, and 701, with ratios to the previous week of 0.68, 0.72, 0.68, 0.62, 0.63, respectively. The use rates of beds are approximately 70% in Shiga, slightly more than 50% in Kyoto and Hyogo, approximately 50% in Wakayama, and approximately 40% in Nara.

  6. Kyushu

    The number of new cases of infection in Fukuoka was approximately 772, with a ratio to the previous week of 0.62. Infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 60%. In Saga, Nagasaki, Kumamoto, Oita, Miyazaki, and Kagoshima, the numbers of new cases of infection were approximately 820, 966, 816, 784, 973, and 1,036, with ratios to the previous week of 0.61, 0.61, 0.66, 0.68, 0.64, and 0.66, respectively. The use rates of beds are slightly more than 40% in Saga, approximately 40% in Miyazaki, and slightly more than 50% in Nagasaki, Kumamoto, Oita, and Kagoshima.

  7. Okinawa

    The number of new cases of infection was approximately 820, with a ratio to the previous week of 0.62. Infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 60%, while the use rate of beds for severe cases is approximately 50%.

  8. Areas other than the above

    The ratios to the previous week in Iwate, Yamagata, and Fukushima were 0.80, 0.88, and 0.83, respectively. The use rate of beds is slightly more than 60% in Aomori, approximately 60% in Tokushima, slightly less than 60% in Kagawa, and slightly more than 50% in Yamagata, Toyama, Nagano, Hiroshima, and Yamaguchi.

Infection status and future outlook

Infection status
  • The number of new cases of infection still indicates a high level of infection nationwide, but it is steadily decreasing in all regions. The level of infection is below the peak at the beginning of February this year in the Tokyo metropolitan and Kansai areas. On the other hand, the level of infection remains higher than the peak of February in many of the other regions, and the decrease in the number of infections has slowed down mainly in northern Japan. In addition, there are still mass infections in facilities for elderly people and medical institutions. The nationwide emergence of new cases of infection and close contacts also continues to affect not only medical institutions and welfare facilities, but also social activities as a whole.
  • The number of new cases of infection in each age group started to decrease nationwide; the extent of the decrease in new cases of infection among young people has grown among those in their 20s since last week. The number of new cases of infection among elderly people is also showing a downward trend, and the number of severe cases has recently began to decrease. On the other hand, the increase in the number of deaths has stopped but remained around the record-high level.
  • As for the place of new infections, the proportion of home remains unchanged in all age groups, but is increasing especially among people in their 20s. The decreasing trend of school changed and the number of infections is increasing after the start of schools after the vacation (it should be noted that only some of the infection routes [~13%] have been detected because of prioritized active epidemiological surveillance).
Future outlook and factors that increase and suppress infection
  • Regarding the future infection status, the decreasing trend in the number of infections may continue in many regions despite regional differences and uncertainty, based on the epi curve of the date of onset and short-term forecast in large cities. On the other hand, the decreasing pace may slow down and the trend may be reversed in some regions because schools started after the break of the summer vacation. The improvement in infection status is expected to relieve medical care provision systems under severe conditions.
  • The main factors affecting the number of infected people include the following.
  1. [Vaccination and immunity from infection]

    It has become clear that as a certain period elapses after the third vaccination, the infection prevention effect is attenuated compared to the aggravation prevention effect. On the other hand, those in their 60s and older are less likely to acquire immunity by infection than those in their 20s to 40s. It is also pointed out that immunity is attenuated, and there is concern that the infection will spread among elderly people in the future.

  2. [Contact patterns]

    The nighttime population curve generally remains flat, and has lately decreased to a large extent, especially in Okinawa. These trends may be due to adverse weather conditions.

  3. [Epidemic strain]

    After the prevalence of the BA.2 lineage, it has almost been replaced by the BA.5 lineage, which has become mainstream.

  4. [Climatic factors]

    Since hot weather is expected to continue for some time in September, the preference for using air conditioners may lead to poor ventilation.

Status of the medical care provision system
  • Nationwide, there is a burden on the outpatient examination system, but the use rate of beds shows a decreasing trend, though it is still at a high level nationwide, and regions with rates below 50% are also increasing. The usage rate of beds for severe cases in Okinawa is 50%, but it is decreasing in many regions. In addition, the number of home care recipients and medical treatment adjustments is decreasing in almost all regions.
  • There is still a burden on the medical care provision system including general medical services, but the status has somewhat improved. On the other hand, in the field of nursing care, many patients are being treated in facilities, and infection is still spreading among patients and workers.
  • Although the number of cases with difficulty to find emergency transportation is decreasing nationwide, some regions still show high levels, and caution should be paid to them.

Measures to be taken

Basic concepts
  • While the infection situation has not been under control, the possibility of contact with a risk of infection should be minimized based on the facts that the Japanese society have already learned.
    To maintain socio-economic activities, everyone has to take measures to prevent infecting others and being infected.
  • To this end, the national and local governments will remind the public of the need for routine infection control measures, and take measures to support the public's efforts to prevent infection. In addition, efforts must be made to reduce the number of infected people so as not to increase the numbers of severe cases and deaths, as much as possible. Furthermore, further efforts should be made to reinforce the medical care provision system, and reduce the burdens on medical institutions and public health centers.
  1. 1. Further promotion of vaccinations
    • In a case-control study investigating the efficacy of the SAR-CoV-2 vaccine in Japan, the prophylactic effect against the disease at 5 months after the second vaccination was low compared to unvaccinated cases in the epidemic period of BA.5. On the other hand, 3 doses of vaccination (booster) were shown to possibly increase the prophylactic effect against the disease to a moderate to high degree. It was preliminarily reported that the relative efficacy rate of 3 doses of vaccination compared with 2 doses can be expected to a certain extent.
    • Concerning “vaccine for the omicron variant,” it is planned to start vaccination of all persons aged 12 years and older who have completed the initial vaccination (first and second dose) around the middle of October, and of those eligible for the fourth vaccination for such reasons as high risk of aggravation of the disease around the middle of September by partial acceleration of the import of the vaccine and using available vaccines for domestic delivery as it becomes available.
    • For the fourth vaccination, it is necessary to continue efforts to provide earlier vaccination for eligible persons (elderly people aged 60 years and older, and those aged less than 60 years at risk for severe illness, etc.) for prophylaxis against exacerbation. Based on the local infection status, vaccination should be promoted among workers in medical institutions and elderly care facilities where people at high risk of severe disease are gathered.
    • Vaccination with recombinant protein may be selected for up to the third vaccination. It has been confirmed that a third vaccination restores the attenuation over time, of both the preventive effect against the Omicron variant and that against aggravation conferred by the first vaccination. Considering the current infection status, it is necessary to promote consideration of the first and third vaccinations at the earliest possible time.
    • Regarding vaccination of children (5-11 years old), the Immunization and Vaccine Section Meeting considered that it was appropriate to impose an obligation to make efforts to vaccinate children, as a certain level of knowledge has been acquired during the spread of the Omicron variant. In addition, the Meeting considered it appropriate to perform additional vaccination.
  2. 2. Use of tests
    • Based on the recommendations of the 17th meeting of the Novel Coronavirus Subcommittee, the national and local governments are required to secure a system that enables testing, and further utilize testing.
    • At facilities for elderly people, frequent tests of workers (approximately 2 or 3 times a week) should be performed. Depending on the circumstances in the area, testing on appropriate occasions is recommended for users of facilities.
    • Depending on the circumstances in the area, if a cluster occurs it is necessary to carry out frequent testing of teachers and staff at nursery schools and kindergartens.
    • At the discretion of local governments and schools, it is necessary to thoroughly observe children’s health, and test those with any symptoms.
    • Preliminary testing is further recommended when having a meal with a large number of people or when interacting with elderly people.
    • Establishment of a self-testing system for fever outpatients should be further promoted, in which patients with symptoms can self-test using an antigen qualitative test kit, and if the result is positive, they can promptly undergo health observation at a health follow-up center, etc.
    • In order to promote these efforts, it is important for the government to provide a stable supply including distribution, by purchasing antigen qualitative test kits, distributing them to prefectural governments, and providing coordination support.
    • It is necessary to further promote the utilization of antigen qualitative test kits as OTC through internet sales.
  3. 3. Effective ventilation
    • Based on the recommendations of the 17th meeting of the Novel Coronavirus Subcommittee, effective methods of ventilation should be announced and encouraged to ensure that the use of air conditioners does not lead to poor ventilation (how to create air flow in consideration of aerosols, installation of a partition that does not block the air flow, etc.).
  4. 4. Securing a medical care provision system
    • With support of the national government, local governments are required to take measures to keep the following hospital beds, fever clinics, etc. from being overcrowded.
    • In addition to facilitating the use of available hospital beds and developing temporary medical facilities to supplement hospital beds, making efforts to avoid a shortage of hospital beds and emergency medical care, such as utilization of lodging facilities and resting beds.
    • Making appropriate adjustments so that patients requiring inpatient treatment can be hospitalized preferentially, performing frequent tests at facilities for elderly people, etc., and further strengthening medical support.
    • Securing and expanding logistical support hospitals, and improving the hospital turnover rate, such as by dissemination of the standard for early discharge of 4 days, as a rule.
    • Promotion of effective and less burdensome measures against infection, such as flexible and efficient use of hospital beds through zoning of each hospital room.
    • Promotion of a basic strategy that is uniformly introduced nationwide to reduce the burden on fever clinics and public health centers, through an emergency measure that makes it possible to limit the scope of notifications of occurrence in regions where fever clinics and public health centers are under extreme pressure.
    • Promotion of the expansion and publicity of fever clinics, including the use of online medical services, etc.
    • Further promotion of the “self-testing system at fever clinics” to allow symptomatic people to test themselves using a qualitative antigen test kit and, if positive, promptly undergo health monitoring at a Health Follow-up Center, etc. In particular, in regions where fever clinics are under pressure and with a limited scope for notification of occurrence, reinforcement of self-testing in fever clinics should be promoted, such as by reinforcing Health Follow-up Centers.
    • Consideration to making announcements to residents depending on their local situations, and in such a manner that they will not refrain from seeking medical care, for example, when residents are asked not to be tested if they are asymptomatic. Announcements about and reinforcement of telephone consultation services for residents are also required to express concerns and questions and be answered by a medical professionals, for example when their condition is worsening.
    • Response to emergency cases that are difficult to transport. Confirm the system of accepting patients other than those with COVID-19, and spread awareness of the prevention of heat stroke.
    • Establishing and reinforcing a system that allows patients to receive a therapeutic drug appropriately and without delay through publication of the drug’s registration status at clinics/medical institutions
    • Ensuring that workplaces and schools do not require test certificates at the start of medical treatment
    • Inspecting and securing an oxygen administration system for patients who temporarily need oxygen administration, such as by securing oxygen concentrators, depending on the patient’s condition of home care, arranged accommodation for care, or elderly-care facilities.
  5. 5. Surveillance
    • The limited scope of notification of occurrence, notified items, delay in testing/diagnosis/reporting due to the many cases of the infection, changes in medical care-seeking behavior, etc. are raising concerns about deterioration of the current surveillance program’s accuracy. To understand the epidemiological status, an effective and appropriate surveillance program should be developed promptly.
      It is also necessary to monitor the trends of variants through genomic surveillance.
  6. 6. Re-inspection and implementation of basic infection control

    Re-inspection and implementation of the following basic infection control measures are needed.

    • Continue proper wearing of nonwoven masks, hand hygiene, thorough ventilation, etc.
    • Avoid situations with a high risk of infection, such as the three Cs, congestion, or loud voices.
    • Eating and drinking should be done with as few people as possible, and masks should be worn except while eating and drinking.
    • People with symptoms such as sore throat, cough, and fever should refrain from going out.
    • Refer to guidelines for hospital visits and use of an ambulance.
    • To reduce the chances of contact as far as possible, it is necessary for measures at the workplace, such as again promoting the use of telework.
    • Organizers of events, meetings, and such should fully evaluate the epidemic situation and risk of infection in the area, and consider whether or not to hold the meeting, and if it is held, measures should be taken to minimize the infection risk.
<< Reference: Findings on the characteristics of the Omicron variant and its sublineages >>
  1. [Infectivity/transmissibility]

    It has been confirmed that compared to the Delta variant, the generation time has shortened to approximately 2 days (approximately 5 days for Delta). The doubling time and incubation period have also shortened, the risk of re-infection and secondary infection after infection has increased, and the speed of infection spread is very fast. According to the reported data, pre-symptomatic transmission has probably occurred to some extent as with the previous strains.

  2. [Place/route of infection]

    In Japan, many cases of infection have occurred through the same opportunities as before (spending time indoors in locations with inadequate ventilation, eating and drinking, etc.), and infection is considered to have occurred via the same routes as before (droplets adhering to mucosa, aerosol inhalation, contact infection, etc.).

  3. [Severity]

    It has been suggested that infection with the Omicron variant presents a lower risk of hospitalization or aggravation than the Delta variant. However, analyses to date show that the fatality due to infection with the Omicron variant is higher than that due to seasonal influenza. It is also suggested that the incidence of pneumonia is higher than that of seasonal influenza, but given the limited data, it needs to be investigated by various analyses. The death toll from the previous outbreak compared to last summer's outbreak had a higher proportion of people aged 80 and over. It is reported that there are many cases in which the new coronavirus infection is not the direct cause of death, for example, people who have been in a facility for the elderly before the infection are infected and die due to the worsening of the underlying disease. Attention should also be paid to worsening of the condition of elderly infected people and infected people with an underlying disease, and to the onset of heart failure and aspiration pneumonia.

  4. [Duration of viral shedding]

    Viral shedding in individuals infected with the Omicron variant decreases over time. In patients with symptoms, it has been shown that the possibility of viral shedding is low from 10 days after the date of onset, and that no shedding is observed after 8 days from the date of diagnosis in those without symptoms.

  5. [Vaccine effect]

    For infection with the Omicron variant, the preventive effects of a first vaccination against infection and disease onset are markedly reduced. Its preventive effect on hospitalization is reported to be maintained at a certain level for the first 6 months, but subsequently decreases to 50% or less. On the other hand, it has been reported overseas that a third vaccination restores the infection-preventing effect, onset-preventing effect, and hospitalization-preventing effect against infection by the Omicron variant, and information on how these vaccine effects are attenuated after a third vaccination has become available. Regarding the fourth vaccination, it has been reported that while the preventive effect against aggravation was not reduced for 6 weeks, the preventive effect against infection lasted only for a short time.

  6. [Sublineages of the Omicron variant]

    Worldwide, the proportion of the BA.5 lineage is increasing while the number of positive cases is increasing, suggesting that this lineage is superior to the BA.2 lineage in terms of causing an increase in the number of infected people, but currently the number of positive cases is decreasing. The BA.5 lineage has shown a tendency to escape existing immunity compared with the BA.1 and BA.2 lineages, but no clear findings on the infectivity have been shown. The effective reproduction number of the BA.5 lineage calculated based on the data of Tokyo was about 1.27 times that of BA.2. It was also estimated that it was about 1.3 times higher in samples collected from private testing institutions nationwide.

    According to the WHO report, the severity of BA.5 lineage shows both increased and unchanged data compared to the existing Omicron variants, and continued information collection is needed. In addition, the pathogenicity of the BA.5 lineage is reportedly higher than that of the BA.1 and BA.2 lineages, based on Japanese laboratory data, but it has not been confirmed clinically at this time. Although it is unknown whether it is due to the traits of the BA.5 lineage, it should be noted that the numbers of inpatient cases and severe cases are increasing in countries where the number of infected people is increasing mainly in the BA.5 lineage. According to genomic surveillance in Japan, the detection rate of the BA.5 lineage is increasing, and the previous dominant variant was replaced by this lineage.

    The BA.2.75 lineage, which has been reported mainly in India since June, and the BA.4.6 lineage, which has been reported mainly in the United States and the United Kingdom, have been detected in Japan. However, no clear findings have been obtained overseas regarding its infectivity or severity, compared with other lineages. It is necessary to continue to collect and analyze the situation and findings in other countries regarding these characteristics of the virus, and to continue monitoring by genome surveillance.

Figures (Number of new infections reported etc.) (PDF)

 

97th Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (August 31, 2022) Material 1

 

Evaluation of the latest infectious status, etc.

Overview of infection status

  • The nationwide number of new cases of infection (based on the reporting dates) was approximately 985 per 100,000 population in the most recent week and the ratio to the previous week was 0.79. Although the number started to decrease after the upward trend in the last week, a high level of infections is continuing nationwide. Attention should be paid to the impact of the re-opening of schools after the summer break on the infection status.
  • As the number of new cases of infection started to decrease, the number of patients receiving treatment also started to decrease. The use rate of beds remains high nationwide.
    The medical care provision system is facing many problems such as difficulty to transport emergency cases and the absence of medical personnel, causing a significant burden not only on COVID-19-related services but on the medical provision system including general medical services.
    The numbers of severe cases and deaths also remain high. In particular, the number of deaths is continuing to exceed the previous record-high level.

    Effective reproduction number: The latest number (as of August 14) is 1.03 nationwide, 0.99 in the Tokyo metropolitan area, and 1.00 in the Kansai area.

Local trends

* The value for new cases of infection is the number of persons per 100,000 among the total number for the latest week, based on the reporting dates.

  1. Hokkaido

    The number of new cases of infection was approximately 733 (approximately 722 in Sapporo City), with a ratio to the previous week of 0.79. The infected individuals are mainly in their 30s or younger. The use rate of beds is approximately 40%.

  2. North Kanto

    In Ibaraki, Tochigi, and Gunma, the numbers of new cases of infection were approximately 825, 665, and 762, with ratios to the previous week of 0.88, 0.75, and 0.85, respectively. In Ibaraki, Tochigi, and Gunma, they were mainly in their 30s or younger. The use rates of beds are slightly more than 60% in Ibaraki, slightly less than 50% in Tochigi, and slightly more than 50% in Gunma.

  3. Tokyo metropolitan area (Tokyo and 3 neighboring prefectures)

    The number of new cases of infection in Tokyo was approximately 883, with a ratio to the previous week of 0.72. The infected individuals are mainly in their 30s or younger. The use rate of beds is approximately 50%, while the use rate of beds for severe patients is slightly more than 30%. In Saitama, Chiba, and Kanagawa, the numbers of new cases of infection were approximately 758, 722, and 617, with ratios to the previous week of 0.80, 0.95, and 0.82, respectively. The use rates of beds are slightly more than 60% in Saitama, Chiba, and Kanagawa.

  4. Chukyo/Tokai

    The number of new cases of infection in Aichi was approximately 1,128, with a ratio to the previous week of 0.76. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 70%. In Gifu, Shizuoka, and Mie, the numbers of new cases of infection were roughly 1,092, 962, and 1,169, with ratios to the previous week of 0.78, 0.83, and 0.81, respectively. The use rate of beds is slightly more than 60% in Gifu and Shizuoka, and slightly more than 50% in Mie.

  5. Kansai area

    The number of new cases of infection in Osaka was approximately 1,151, with a ratio to the previous week of 0.72. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 60%, while the use rate of beds for severe patients is slightly more than 10%. In Shiga, Kyoto, Hyogo, Nara, and Wakayama, the numbers of new cases of infection were roughly 1,144, 1,078, 1,117, 1,126, and 1,108, with ratios to the previous week of 0.90, 0.87, 0.81, 0.82, and 0.76, respectively. The use rates of beds are slightly more than 60% in Shiga, Hyogo, and Wakayama, slightly less than 60% in Kyoto, and slightly more than 50% in Nara.

  6. Kyushu

    The number of new cases of infection in Fukuoka was approximately 1,250, with a ratio to the previous week of 0.73. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 70%. In Saga, Nagasaki, Kumamoto, Oita, Miyazaki, and Kagoshima, the numbers of new cases of infection were approximately 1,354, 1,578, 1,235, 1,160, 1,516, and 1,560, with ratios to the previous week of 0.69, 0.84, 0.73, 0.75, 0.79, and 0.80, respectively. The use rates of beds are slightly less than 50% in Saga, slightly more than 60% in Nagasaki, Kumamoto, and Kagoshima, slightly more than 50% in Oita, and slightly more than 40% in Miyazaki.

  7. Okinawa

    The number of new cases of infection was approximately 1,329, with a ratio to the previous week of 0.76. The infected individuals are mainly in their 30s or younger. The use rate of beds is approximately 60%, while the use rate of beds for severe cases is slightly more than 30%.

  8. Areas other than the above

    Aomori, Ishikawa, Tokushima, and Kochi had ratios to the previous week of 1.07, 0.91, 1.01, and 0.91, respectively. The use rates of beds are approximately more than 70% in Aomori, approximately 60% in Nagano, Hiroshima, and Yamaguchi, slightly less than 70% in Tokushima, and slightly more than 60% in Kagawa and Ehime.

Infection status and future outlook

Infection status
  • Although the number of new cases of infection started to decrease after the upward trend the previous week following the Obon break, a high level of infections is continuing nationwide, still remaining high in some regions. Outbreaks continue to occur in elderly-care facilities and medical institutions. The nationwide emergence of new cases of infection and close contacts also continues to affect not only medical institutions and welfare facilities, but also social activities as a whole.
  • The nationwide number of new cases of infection started to decrease in all age groups. In the 20s, in particular, the number started to decrease after the steep increase the previous week, and the decreasing slope is becoming steeper. Although the number of new cases among elderly people also tended to decrease, the numbers of severe cases and deaths still remain high. In particular, the number of deaths is continuing to exceed the previous record-high level.
  • Of the places where new infections occur, the proportion accounted for by home tended to remain unchanged while the proportion accounted for by schools, etc. tended to increase after the previous downward trend. The proportion accounted for by office (workplace) generally tended to increase among people in their 20s to 60s. (It should be noted that the route of infection is not fully established in large cities because of the focused approach of active epidemiological surveillance.)
Future outlook and factors that promote and suppress infection
  • The epi curve by date of onset and the short-term forecast in large cities indicate that although there are regional differences and uncertainties, there is a possibility that the trend is turning downward from the plateau, but there is concern that the trend may be turning upward due to the impact of schools that will re-open after the summer break. The level of infection is still high nationwide, and the difficult situation of the medical care provision system is expected to continue.
  • The main factors affecting the number of infected cases include the following.
  1. [Vaccination and immunity from infection]

    It has become clear that as a certain period elapses after the third vaccination, the infection prevention effect is attenuated compared to the aggravation prevention effect. On the other hand, those in their 60s and older are less likely to acquire immunity by infection than those in their 20s to 40s. It is also pointed out that immunity is attenuated, and there is concern that the infection will spread among elderly people in the future.

  2. [Contact pattern]

    The nighttime population has remained unchanged nationwide, while it has started to increase in large cities such as Tokyo, Aichi, and Osaka.

  3. [Epidemic strain]

    After the prevalence of the BA.2 lineage, it has almost been replaced by the BA.5 lineage, which has become mainstream.

  4. [Climatic factors]

    Since hot weather is expected to continue for some time in September, the preference for using air conditioners may lead to poor ventilation.

Status of the medical care provision system
  • Nationwide, there is a burden on the outpatient examination system, and the use rate of beds remains high nationwide, exceeding 50% in most regions. The use rate of beds for severe cases was below 50% in Tokyo and Osaka, but 50% in Kochi. The numbers of patients in home care and arranged accommodation for care remain high in many regions, but is tending to decrease.
  • Nationwide, infection among health care professionals has caused inadequate staffing to continue, prolonging the burden on the medical care provision system, including general medical services. In the field of nursing care, in-facility treatment is often encountered, and infection among patients under treatment and their carers is prolonging the difficult situation.
  • The positive test rate tended to decrease, but still remained high, raising concerns about whether people who need to undergo testing, such as those who are symptomatic, can receive the tests appropriately.
  • The number of emergency cases that were difficult to transport decreased nationwide, but in some regions the number still remained high, and requires attention.
    Continued attention is needed for emergency transportation under the influence of extremely hot weather.

Measures to be taken

Basic concepts
  • While the infection situation has not been under control, the possibility of contact with a risk of infection should be minimized based on the facts that the Japanese society have already learned.
    To maintain socio-economic activities, everyone has to take measures to prevent infecting others and being infected.
  • To this end, the national and local governments will remind the public of the need for routine infection control measures, and take measures to support the public's efforts to prevent infection. In addition, efforts must be made to reduce the number of infected people so as not to increase the numbers of severe cases and deaths, as much as possible. Furthermore, further efforts should be made to reinforce the medical care provision system, and reduce the burdens on medical institutions and public health centers.
  1. 1. Further promotion of vaccinations
    • In a case-control study investigating the efficacy of the SAR-CoV-2 vaccine in Japan, the prophylactic effect against the disease at 5 months after the second vaccination was low compared to unvaccinated cases in the epidemic period of BA.5. On the other hand, 3 doses of vaccination (booster) were shown to possibly increase the prophylactic effect against the disease to a moderate to high degree. It was preliminarily reported that the relative efficacy rate of 3 doses of vaccination compared with 2 doses can be expected to a certain extent.
    • Regarding the booster vaccination with "vaccine for the Omicron variant," it will be prepared for use after the middle of October this year, targeting those who have completed the initial vaccination.
    • For the fourth vaccination, it is necessary to continue efforts to provide earlier vaccination for eligible persons (elderly people aged 60 years and older, and those aged less than 60 years at risk for severe illness, etc.) for prophylaxis against exacerbation. Based on the local infection status, vaccination should be promoted among workers in medical institutions and elderly care facilities where people at high risk of severe disease are gathered.
    • Vaccination with recombinant protein may be selected for up to the third vaccination. It has been confirmed that a third vaccination restores the attenuation over time, of both the preventive effect against the Omicron variant and that against aggravation conferred by the first vaccination. Considering the current infection status, it is necessary to promote consideration of the first and third vaccinations at the earliest possible time.
    • Regarding vaccination of children (5-11 years old), the Immunization and Vaccine Section Meeting considered that it was appropriate to impose an obligation to make efforts to vaccinate children, as a certain level of knowledge has been acquired during the spread of the Omicron variant.
  2. 2. Use of tests
    • Based on the recommendations of the 17th meeting of the Novel Coronavirus Subcommittee, the national and local governments are required to secure a system that enables testing, and further utilize testing.
    • Frequent tests (about 2 or 3 times a week for facility workers) are required for workers at facilities for elderly people.
    • Depending on the circumstances in the area, testing at appropriate occasions is recommended for users of facilities for elderly people.
    • Depending on the circumstances in the area, if a cluster occurs it is necessary to carry out frequent testing of teachers and staff at nursery schools and kindergartens.
    • At the discretion of local governments and schools, it is necessary to thoroughly observe children’s health, and test those with any symptoms.
    • Preliminary testing is further recommended when having a meal with a large number of people or when interacting with elderly people.
    • Establishment of a self-testing system for fever outpatients should be further promoted, in which patients with symptoms can self-test using an antigen qualitative test kit, and if the result is positive, they can promptly undergo health observation at a health follow-up center, etc.
    • In order to promote these efforts, it is important for the government to provide a stable supply including distribution, by purchasing antigen qualitative test kits, distributing them to prefectural governments, and providing coordination support.
    • It is necessary to promote the utilization of antigen qualitative test kits as OTC.
  3. 3. Effective ventilation
    • Based on the recommendations of the 17th meeting of the Novel Coronavirus Subcommittee, effective methods of ventilation should be announced and encouraged to ensure that the use of air conditioners does not lead to poor ventilation (how to create air flow in consideration of aerosols, installation of a partition that does not block the air flow, etc.).
  4. 4. Securing a medical care provision system
    • With support of the national government, local governments are required to take measures to keep the following hospital beds, fever clinics, etc. from being overcrowded.
    • In addition to facilitating the use of available hospital beds and developing temporary medical facilities to supplement hospital beds, making efforts to avoid a shortage of hospital beds and emergency medical care, such as utilization of lodging facilities and resting beds
    • Making appropriate adjustments so that patients requiring inpatient treatment can be hospitalized preferentially, performing frequent tests at facilities for elderly people, etc., and further strengthening medical support
    • Securing and expanding logistical support hospitals, and improving the hospital turnover rate, such as by dissemination of the standard for early discharge of 4 days, as a rule
    • Promotion of effective and less burdensome measures against infection, such as flexible and efficient use of hospital beds through zoning of each hospital room
    • Promotion of a basic strategy that is uniformly introduced nationwide to reduce the burden on fever clinics and public health centers, through an emergency measure that makes it possible to limit the scope of notifications of occurrence in regions where fever clinics and public health centers are under extreme pressure.
    • Promotion of the expansion and publicity of fever clinics, including the use of online medical services, etc.
    • Further promotion of the “self-testing system at fever clinics” to allow symptomatic people to test themselves using a qualitative antigen test kit and, if positive, promptly undergo health monitoring at a Health Follow-up Center, etc. In particular, in regions where fever clinics are under pressure and with a limited scope for notification of occurrence, reinforcement of self-testing in fever clinics should be promoted, such as by reinforcing Health Follow-up Centers.
    • Consideration to making announcements to residents depending on their local situations, and in such a manner that they will not refrain from seeking medical care, for example, when residents are asked not to be tested if they are asymptomatic. Announcements about and reinforcement of telephone consultation services for residents are also required to express concerns and questions and be answered by a medical professionals, for example when their condition is worsening.
    • Response to emergency cases that are difficult to transport. Confirm the system of accepting patients other than those with COVID-19, and spread awareness of the prevention of heat stroke.
    • Establishing and reinforcing a system that allows patients to receive a therapeutic drug appropriately and without delay through publication of the drug’s registration status at clinics/medical institutions
    • Ensuring that workplaces and schools do not require test certificates at the start of medical treatment
    • Inspecting and securing an oxygen administration system for patients who temporarily need oxygen administration, such as by securing oxygen concentrators, depending on the patient’s condition of home care, arranged accommodation for care, or elderly-care facilities.
  5. 5. Surveillance
    • The limited scope of notification of occurrence, notified items, delay in testing/diagnosis/reporting due to spreading of the infection, changes in medical care-seeking behavior, etc. are raising concerns about deterioration of the current surveillance program’s accuracy. To understand the epidemiological status, an effective and appropriate surveillance program should be developed promptly.
      It is also necessary to monitor the trends of variants through genomic surveillance.
  6. 6. Re-inspection and implementation of basic infection control

    Re-inspection and implementation of the following basic infection control measures are needed.

    • Eating and drinking should be done with as few people as possible, and masks should be worn except while eating and drinking.
    • Continue proper wearing of nonwoven masks, hand hygiene, thorough ventilation, etc.
    • People with symptoms such as sore throat, cough, and fever should refrain from going out.
    • Avoid situations with a high risk of infection, such as the three Cs, congestion, or loud voices.
    • Refer to guidelines for hospital visits and use of an ambulance.
    • To reduce the chances of contact as far as possible, it is necessary for measures at the workplace, such as again promoting the use of telework.
    • Organizers of events, meetings, and such should fully evaluate the epidemic situation and risk of infection in the area, and consider whether or not to hold the meeting, and if it is held, measures should be taken to minimize the infection risk.
<< Reference: Findings on the characteristics of the Omicron variant and its sublineages >>
  1. [Infectivity/transmissibility]

    It has been confirmed that compared to the Delta variant, the generation time has shortened to approximately 2 days (approximately 5 days for Delta). The doubling time and incubation period have also shortened, the risk of re-infection and secondary infection after infection has increased, and the speed of infection spread is very fast. According to the reported data, pre-symptomatic transmission has probably occurred to some extent as with the previous strains.

  2. [Place/route of infection]

    In Japan, many cases of infection have occurred through the same opportunities as before (spending time indoors in locations with inadequate ventilation, eating and drinking, etc.), and infection is considered to have occurred via the same routes as before (droplets adhering to mucosa, aerosol inhalation, contact infection, etc.).

  3. [Severity]

    It has been suggested that infection with the Omicron variant presents a lower risk of hospitalization or aggravation than the Delta variant. However, analyses to date show that the fatality due to infection with the Omicron variant is higher than that due to seasonal influenza. It is also suggested that the incidence of pneumonia is higher than that of seasonal influenza, but given the limited data, it needs to be investigated by various analyses. The death toll from the previous outbreak compared to last summer's outbreak had a higher proportion of people aged 80 and over. It is reported that there are many cases in which the new coronavirus infection is not the direct cause of death, for example, people who have been in a facility for the elderly before the infection are infected and die due to the worsening of the underlying disease. Attention should also be paid to worsening of the condition of elderly infected people and infected people with an underlying disease, and to the onset of heart failure and aspiration pneumonia.

  4. [Duration of viral shedding]

    Viral shedding in individuals infected with the Omicron variant decreases over time. In patients with symptoms, it has been shown that the possibility of viral shedding is low from 10 days after the date of onset, and that no shedding is observed after 8 days from the date of diagnosis in those without symptoms.

  5. [Vaccine effect]

    For infection with the Omicron variant, the preventive effects of a first vaccination against infection and disease onset are markedly reduced. Its preventive effect on hospitalization is reported to be maintained at a certain level for the first 6 months, but subsequently decreases to 50% or less. On the other hand, it has been reported overseas that a third vaccination restores the infection-preventing effect, onset-preventing effect, and hospitalization-preventing effect against infection by the Omicron variant, and information on how these vaccine effects are attenuated after a third vaccination has become available. Regarding the fourth vaccination, it has been reported that while the preventive effect against aggravation was not reduced for 6 weeks, the preventive effect against infection lasted only for a short time.

  6. [Sublineages of the Omicron variant]

    Worldwide, the proportion of the BA.5 lineage is increasing while the number of positive cases increases, suggesting that this lineage is superior to the BA.2 lineage in terms of causing an increase in the number of infected people, but recently the number of positive cases has decreased. The BA.5 lineage has shown a tendency to escape existing immunity compared with the BA.1 and BA.2 lineages, but no clear findings on the infectivity have been shown. The effective reproduction number of the BA.5 lineage calculated based on the data of Tokyo was about 1.27 times that of BA.2. It was also estimated that it was about 1.3 times higher in samples collected from private testing institutions nationwide.

    According to the WHO report, the severity of BA.5 lineage shows both increased and unchanged data compared to the existing Omicron variants, and continued information collection is needed. In addition, the pathogenicity of the BA.5 lineage is reportedly higher than that of the BA.1 and BA.2 lineages, based on Japanese laboratory data, but it has not been confirmed clinically at this time. Although it is unknown whether it is due to the traits of the BA.5 lineage, it should be noted that the numbers of inpatient cases and severe cases are increasing in countries where the number of infected people is increasing mainly in the BA.5 lineage. According to genomic surveillance in Japan, the detection rate of the BA.5 lineage is increasing, and the previous dominant variant was replaced with this lineage.

    In addition, the BA.2.75 lineage, which has been reported mainly in India since June, has been detected in Japan. However, no clear findings have been obtained overseas regarding its infectivity or severity, compared with other lineages. It is necessary to continue to collect and analyze the situation and findings in other countries regarding these characteristics of the virus, and to continue monitoring by genome surveillance.

Figures (Number of new infections reported etc.) (PDF)

 

掲載日:2022年9月14日
一部追加:2022年9月15日


国立感染症研究所実地疫学研究センター
同     感染症疫学センター   

 

新型コロナウイルス感染症に罹患し、お亡くなりになった方々とご遺族の皆様に対し、深くお悔やみを申し上げます。

 

背景・目的

 厚生労働省は、新型コロナウイルス(以下、「SARS-CoV-2」という。)感染による重症度等の知見を集積・監視するため、感染症の予防及び感染症の患者に対する医療に関する法律(平成10年法律第114号。)第15条に基づく積極的疫学調査の一環として、「新型コロナウイルス感染症の積極的疫学調査におけるゲノム解析及び変異株PCR検査について(要請)」(令和3年2月5日付け健感発0205第4号厚生労働省健康局結核感染症課長通知。令和4年2月10日一部改正。)及び「B.1.1.529系統(オミクロン株)の感染が確認された患者等に係る入退院及び濃厚接触者並びに公表等の取扱いについて」(令和3年11月30日付け厚生労働省新型コロナウイルス感染症対策推進本部事務連絡。令和4年2月2日一部改正。)において、自治体に対し、重症例及び死亡例についての報告やゲノム解析をこれまで依頼してきた。
 今般、感染拡大に伴い、小児の感染者数が増加し1)、小児の重症例、死亡例発生への懸念から、厚生労働省及び国立感染症研究所は、関係学会(日本小児科学会、日本集中治療医学会、日本救急医学会)と協力して、SARS-CoV-2感染後の20歳未満の死亡例(以下、小児等の死亡例という。)について、急性期以降の死亡例も含め幅広く調査対象とし、積極的疫学調査を実施することとした。
 本報告は、2022年1月1日から2022年8月31日までに報告された小児等の死亡例に関する暫定的な報告である。

 

方法

報告された小児等の死亡例のうち、下記2つのうちいずれかを満たす者を調査対象とした。自治体及び医療機関の協力のもと、国立感染症研究所職員及び実地疫学専門家養成コース研修員が、自治体による疫学調査等の資料収集、可能な限り現地に赴き実地においての医療機関での診療録の閲覧、及び医師への聞き取り等の調査(以下、実地調査という。)を実施した。

調査対象とした者:

①発症日(あるいは入院日)が2022年1月1日以降のSARS-CoV-2感染後の20歳未満の急性期の死亡例

②発症日(あるいは入院日)が2022年1月1日以降のSARS-CoV-2感染後の20歳未満の急性期以後に死亡した症例(死因を別原因とした症例。発症からの日数は問わない。)

実地調査における主な調査項目:
 年齢、性別、基礎疾患、新型コロナワクチン接種歴、発症日、死亡日、症状/所見、死亡に至る経緯等

 

結果(暫定)

本調査における2022年8月31日現在の症例の概要、及び実地調査の結果は、以下のとおりであった。症例の収集において、調査対象を上述の①または②を満たす者としたが、報告された症例について①と②を明確に分類することは困難であった。なお、下記の記述内容は個人が特定されないよう配慮した。

〇症例の概要
 症例は、2022年8月31日時点で、計41例(年齢:0歳8例(20%)、1-4歳10例(24%)、5-11歳17例(41%)、12-19歳5例(12%)、不明1例(2%)、性別:男性23例(56%)、女性18例(44%)、基礎疾患:あり18例(44%)、なし17例(41%)、不明6例(15%))であった。2022年1月1日(疫学週2021年52週)以降の発症日に基づく報告数を図に示した。症例は、2022年1月から継続的に発生し、疫学週2022年28週(7月11日~7月17日)から増加した。

図.新型コロナウイルス感染後の20歳未満の死亡例の報告数(n=34; 発症日または入院日が2022年1月1日(疫学週2021年52週)~8月31日(疫学週2022年35週))(2022年8月31日時点)**
*発症日不明の7例を除く
**直近の報告はグラフに反映されにくいため、解釈には注意が必要である。

〇実地調査の結果
 41例のうち実地調査が実施できた症例は、2022年8月31日時点で32例であり、このうち、明らかな内因性死亡(外傷を除く疾病による死亡)と考えられたのは29例であった。以下、この29例について述べる(表)。
 年齢・年代の内訳は、0歳8例(28%)、1-4歳6例(21%)、5-11歳12例(41%)、12-19歳3例(10%)であった。性別は、男性16例(55%)、女性13例(45%)であった。基礎疾患は、あり14例(48%)、なし15例(52%)であった。2022年8月31日時点での基礎疾患ありの内訳は、中枢神経疾患7例(50%)、先天性心疾患2例(14%)、染色体異常2例(14%)等であった(重複あり)。新型コロナワクチンは、29例のうち接種対象外年齢の者が14例(48%)、接種対象年齢の者が15例(52%)であり、接種対象年齢となる5歳以上の15例では、未接種が13例(87%)、2回接種が2例(13%)であった。接種を受けた2例はともに12歳以上であり、発症日は、最終接種日から最低3ヶ月を経過していた。また、医療機関到着時の症状/所見は、発熱23例(79%)、悪心嘔吐15例(52%)、意識障害13例(45%)、咳嗽9例(31%)、経口摂取不良9例(31%)、痙攣8例(28%)、呼吸困難7例(24%)の順に多かった。医療機関において疑われた死亡に至る主な経緯は、循環器系の異常7例(24%:心筋炎、不整脈等)、中枢神経系の異常7例(24%:急性脳症等)、呼吸器系の異常3例(10%:肺炎、細菌性肺炎等)、その他6例(21%:多臓器不全等)、原因不明6例(21%)であった。急性脳症等の中枢神経系の異常、心筋炎や不整脈等の循環器系の異常によって急激な経過を辿った症例があった。発症日は、29例のうち26例について得られ、発症から死亡までの日数が、中央値4日(範囲:0-74日)、内訳は0-2日が8例(31%)、3-6日が11例(42%)、7日以上が7例(27%)であった。

29例のうち基礎疾患があったと考えられた14例について、年齢・年代の内訳は、5歳未満8例(57%)(うち0歳4例)、5歳以上6例(43%)であった。性別は、男性9例(64%)、女性5例(36%)であった。医療機関到着時の症状/所見は、発熱11例(79%)、呼吸困難7例(50%)、悪心嘔吐6例(43%)、咳嗽5例(36%)、経口摂取不良4例(29%)、痙攣3例(21%)、意識障害3例(21%)であった。医療機関において疑われた死亡に至る主な経緯として、循環器系の異常3例(21%)、呼吸器系の異常3例(21%)、中枢神経系の異常2例(14%)、その他3例(21%)、原因不明3例(21%)であった。発症日は、14例のうち12例について得られ、発症から死亡までの日数は、中央値4日(範囲:1-74日)、内訳は0-2日が3例(25%)、3-6日が7例(58%)、7日以上が2例(17%)であった。

29例のうち基礎疾患がなかったと考えられた15例について、年齢・年代の内訳は、5歳未満6例(40%)(うち0歳4例)、5歳以上9例(60%)であった。性別は、男性7例(47%)、女性8例(53%)であった。医療機関到着時の症状/所見は、発熱12例(80%)、意識障害10例(67%)、悪心嘔吐9例(60%)、痙攣5例(33%)、経口摂取不良5例(33%)、咳嗽4例(27%)、呼吸困難0例(0%)であった。医療機関において疑われた死亡に至る主な経緯は、中枢神経系の異常5例(33%)、循環器系の異常4例(27%)、その他3例(20%)、原因不明3例(20%)であり、呼吸器系の異常はなかった。発症日は、15例のうち14例について得られ、発症から死亡までの日数は、中央値4.5日(範囲:0-15日)、内訳は0-2日が5例(36%)、3-6日が4例(29%)、7日以上が5例(36%)であった。

 

表. 新型コロナウイルス感染後の20歳未満の死亡例の特性
(n=29 ; 発症日または入院日が2022年1月1日から8月31日、明らかな内因性死亡に限る)(2022年8月31日時点)

* 発症から死亡までの日数は発症日に関する情報が得られた26例(基礎疾患あり12例、基礎疾患なし14例)

 

考察

 2022年8月31日時点における、2022年1月1日から2022年8月31日までに報告された小児等の死亡例、41例について暫定的な報告を行った。症例数は、7月中旬から増加していた。
 今回の実地調査で内因性死亡が明らかとされた小児等の死亡例において、基礎疾患のなかった症例も死亡していることから、SARS-CoV-2感染後は、基礎疾患のある者はもちろん、基礎疾患のない者においても、症状の経過を注意深く観察することが必要であると考えられた。新型コロナワクチンは、接種対象でも多くの小児の死亡例では未接種であった。また、症状は、日本小児科学会による国内小児におけるCOVID-19レジストリ調査2)と比較して、呼吸器症状以外の症状のうち、悪心嘔吐(52%)、意識障害(45%)、経口摂取不良(31%)、痙攣(28%)の割合が高かった。新型コロナウイルス感染症における重症度分類は、主に呼吸器症状等により分類されているが3)、小児においては、痙攣、意識障害などの神経症状や、嘔吐、経口摂取不良等の呼吸器症状以外の全身症状の出現にも注意を払う必要があると考えられた。発症から死亡までの日数は、1週間未満が73%を占めており、特に発症後1週間の症状の経過観察が重要であると考えられた。

 

調査に関する制限と今後

本報告は、2022年8月31日時点での暫定的な報告であり、今後の調査の進捗にあわせて、情報の更新・修正がなされる可能性がある点、及び本調査では、SARS-CoV-2感染と死亡との因果関係を検討していない点に留意する必要がある。引き続き、自治体及び関係学会の協力のもと、本調査を継続していく予定である。

 

本調査における協力学会:日本小児科学会、日本集中治療医学会、日本救急医学会 

謝辞:本調査にご協力いただきました関係者の皆様に心より御礼申し上げます。

 

参考資料

1. 厚生労働省 データからわかる-新型コロナウイルス感染症情報

https://covid19.mhlw.go.jp/ (閲覧日:2022年8月19日)

2. 小児科学会 予防接種・感染症対策委員会「データベースを用いた国内発症小児 Coronavirus Disease 2019 (COVID-19) 症例の臨床経過に関する検討」の中間報告:第3報、2022年3月28日

http://www.jpeds.or.jp/uploads/files/20220328_tyukan_hokoku3.pdf

3. 新型コロナウイルス感染症診療の手引き・第8.0版

https://www.mhlw.go.jp/content/000967699.pdf

 

追加:(2022/9/15)参考資料1.の引用表記を追記しました。

 

96th Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (August 24, 2022) Material 1

 

Evaluation of the latest infectious status, etc.

Overview of the infection status

  • The number of new cases of infection nationwide (based on the reporting dates) is approximately 1,250 per 100,000 population for the latest week, and the ratio to the previous week is 1.19, which is an increase from last week's downward trend. The highest number ever as been surpassed, as the highest level of infection continues. Increase was seen in most regions, partly due to the influence of socio-economic activities such as Obon and summer vacation.
  • As the number of new cases of infection start to increase, the number of patients receiving treatment is also starting to increase. In addition, the use rate of beds is increasing or remains high nationwide. As for the medical care provision system, many cases of difficult emergency transportation and absences of healthcare professionals from work have placed a significant burden not only on treatment for COVID-19, but also on the medical care provision system, including general medical care. There are concerns that the situation will deteriorate further.
    In addition, the numbers of severe cases and deaths are on the rise, and there is particular concern that the number of deaths may further increase to exceed the previous record-high.

    Effective reproduction number: On a national basis, the most recent number is 0.96 (as of August 7), while the figure stands at 0.92 in the Tokyo metropolitan area and 0.94 in the Kansai area.

Local trends

* The value for new cases of infection is the number of persons per 100,000 among the total number for the latest week, based on the reporting dates.

  1. Hokkaido

    The number of new cases of infection was approximately 933 (approximately 957 in Sapporo City), with a ratio to the previous week of 1.07. The infected individuals are mainly in their 30s or younger. The use rate of beds is approximately 40%.

  2. North Kanto

    In Ibaraki, Tochigi, and Gunma, the numbers of new cases of infection were roughly 940, 889, and 900, with ratios to the previous week of 1.31, 1.29 and 1.16, respectively. In Ibaraki, Tochigi, and Gunma, they were mainly in their 30s or younger. The use rates of beds are slightly more than 60% in Ibaraki, slightly less than 70% in Tochigi, and slightly less than 60% in Gunma.

  3. Tokyo metropolitan area (Tokyo and 3 neighboring prefectures)

    The number of new cases of infection in Tokyo was approximately 1,221, with a ratio to the previous week of 0.96. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 50%, while the use rate of beds for severe cases is about 60%. In Saitama, Chiba, and Kanagawa, the numbers of new cases of infection were approximately 946, 764, and 756, with ratios to the previous week of 1.04, 1.06, and 0.94, respectively. The use rate of beds is slightly more than 60% in Saitama and Chiba and slightly more than 70% in Kanagawa.

  4. Chukyo/Tokai

    The number of new cases of infection in Aichi was approximately 1,476, with a ratio to the previous week of 1.34. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 70%. In Gifu, Shizuoka, and Mie, the numbers of new cases of infection were roughly 1,398, 1,165, and 1,449, with ratios to the previous week of 1.31, 1.27, and 1.51, respectively. The use rates of beds are slightly less than 60% in Gifu, approximately 70% in Shizuoka, and slightly more than 50% in Mie.

  5. Kansai area

    The number of new cases of infection in Osaka was approximately 1,601, with a ratio to the previous week of 1.22. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 70%, while the use rate of beds for severe cases is approximately 50%. In Shiga, Kyoto, Hyogo, Nara, and Wakayama, the numbers of new cases of infection were roughly 1,267, 1,240, 1,378, 1,378, and 1,458, with ratios to the previous week of 1.12, 1.04, 1.13, 1.26, and 1.20, respectively. The use rates of beds are approximately 70% in Shiga, and slightly more than 60% in Kyoto, Hyogo, Nara, and Wakayama.

  6. Kyushu

    The number of new cases of infection in Fukuoka was approximately 1,714, with a ratio to the previous week of 1.24. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 70%. In Saga, Nagasaki, Kumamoto, Oita, Miyazaki, and Kagoshima, the numbers of new cases of infection were approximately 1,956, 1,890, 1,697, 1,536, 1,908, and 1,947, with ratios to the previous week of 1.45, 1.33, 1.38, 1.26, 1.20, and 1.27, respectively. The use rates of beds are slightly more than 50% in Saga, Nagasaki, and Miyazaki, slightly more than 60% in Kumamoto and Kagoshima, and slightly less than 60% in Oita.

  7. Okinawa

    The number of new cases of infection was approximately 1,758, with a ratio to the previous week of 0.99. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 70%, while the use rate of beds for severe patients is slightly more than 30%.

  8. Areas other than the above

    The ratios to the previous week in Akita, Yamagata, Fukushima, Toyama, Shimane, Tokushima, Ehime, and Kochi are 1.61, 1.46, 1.45, 1.56, 1.53, 1.79, 1.43, and 1.41, respectively. The use rates of beds are slightly more than 80% in Aomori, slightly more than 60% in Niigata and Okayama, slightly less than 70% in Nagano and Ehime, and slightly more than 70% in Hiroshima.

Infection status and future outlook

Infection status
  • The number of new cases of infection increased in most regions, partly due to the increase in socio-economic activities such as Obon and summer vacation. In many regions and nationwide, the highest infection levels continue, surpassing all-time highs. In addition, there are some regions where the number once tended to decrease or remained high, in which rapid increase continues. On the other hand, in Tokyo, Kanagawa, and Okinawa, a decreasing trend can also be seen. In addition, the number of “patients receiving treatment within facilities” has actually been increasing due to a rapid increase in mass infections at facilities for elderly people and shortages of beds. In addition, the rapid increase in cases of infection and close contacts nationwide is still affecting not only medical institutions and welfare facilities, but also social activities as a whole.
  • The number of new cases of infection in each age group started to increase nationwide, except among those under the age of 10, with a particularly large increase among those in their 20s. On the other hand, as the trend was before, increases in the number of severe cases and deaths tend to lag behind the rapid increase in the number of new infections. The number of deaths in particular continue to rapidly increase, and there is concern that there will be a further increase in the number of deaths in the future that will exceed the previous record-high number.
  • Regarding the place of contracting new infections, the rate of infections that develop at home is still showing an increasing trend, while at schools the trend is changing from decrease to increase. In addition, the percentage of people who contracted the infection at the office (workplace) has increased among people in their 20s to 60s. (It must be kept in mind that active epidemiological surveillance is focused on large cities, and that infection routes are not fully understood).
Future outlook and factors that increase and suppress infection
  • Regarding future infection status, the number of new infections may continue to increase or remain high in many regions, based on the epi curve of the date of onset and short-term forecast in large cities. There is also concern about the effects of the reopening of schools after the summer vacation. The number of infected people is unlikely to decrease soon, and the severe situation in the medical care system is expected to continue.
  • The main factors affecting the number of infected people include the following.
  1. [Vaccination and immunity from infection]

    It has become clear that as a certain period elapses after the third vaccination, the infection prevention effect is attenuated compared to the aggravation prevention effect. On the other hand, those in their 60s or older are less likely to acquire immunity by infection than those in their 20s to 40s. It is also pointed out that immunity is attenuated, and there is concern that the infection will spread further among elderly people in the future.

  2. [Contact patterns]

    The nighttime population curve generally remains flat, and in many areas such as Tokyo and Osaka, it tends to decrease.

  3. [Epidemic strain]

    After the prevalence of the BA.2 lineage, it has almost been replaced by the BA.5 lineage, which has become mainstream. The BA.5 lineage is thought to cause an increase the number of infected persons more easily, and there is concern about immune escape, which may be a factor to increase the number of infected persons.

  4. [Climatic factors]

    Although it was late August, the weather was still hot, and ventilation may be difficult because air conditioning is prioritized.

Status of the medical care provision system
  • Nationwide, the burden on the outpatient examination system is increasing, and the use rate of beds has increased or remains high nationwide, exceeding 50% in most regions. The use rate of beds for severe patients now exceeds 50% in Tokyo and Osaka. In addition, the numbers of home care recipients and medical treatment adjustments remain high in many regions or continue to increase.
  • Sufficient manpower cannot be secured yet due to an increase in infections among healthcare professionals nationwide, including Okinawa. The burden on the medical care provision systems has persisted and includes general medical services. In the field of nursing care too, the difficult situation continues due to the increasing numbers of patients being treated in facilities and infection among workers.
  • The positive rate of the test remains high, complicating assessment. There is also concern whether the test is appropriately performed on those who need it, such as symptomatic people.
  • Although the number of cases of difficulty in emergency transport has decreased nationwide, such cases have increased in some regions and caution should be paid to them. In addition, careful attention should be paid to the increase in cases of ambulance transportation due to the effects of the continuing hot weather.

Measures to be taken

Basic concepts
  • In the midst of the spread of infection, it is necessary to reduce, as much as possible the chances of contacts that risk infection, based on the various knowledge that Japanese society has already learned.
    Also, in order to maintain socio-economic activities, it is necessary to work on methods for people to avoid infecting and being infected.
  • To this end, the national and local governments will remind the public of the need for routine infection control measures, and take measures to support the public's efforts to prevent infection. In addition, efforts must be made to reduce the number of infected people so as not to increase the numbers of severe cases and deaths, as much as possible. Furthermore, further efforts should be made to reinforce the medical care provision system, and reduce the burdens on medical institutions and public health centers.
  1. 1. Further promotion of vaccinations
    • In a case-control study investigating the efficacy of the SAR-CoV-2 vaccine in Japan, the prophylactic effect against the disease at 5 months after the second vaccination was low compared to unvaccinated cases in the epidemic period of BA.5. On the other hand, 3 doses of vaccination (booster) were shown to possibly increase the prophylactic effect against the disease to a moderate to high degree. It was preliminarily reported that the relative efficacy rate of 3 doses of vaccination compared with 2 doses can be expected to a certain extent.
    • Regarding the booster vaccination with "vaccine for the Omicron variant," it will be prepared for use after the middle of October this year, targeting those who have completed the initial vaccination.
    • For the fourth vaccination, it is necessary to continue efforts to provide earlier vaccination for eligible persons (elderly people aged 60 years and older, and those aged less than 60 years at risk for severe illness, etc.) for prophylaxis against exacerbation. Considering the ongoing spread of infection, workers at medical institutions, facilities for elderly people, etc. where many individuals who are at high risk of becoming severely ill gather, have also been included in those who are eligible for vaccination.
    • Vaccination with recombinant protein may be selected for up to the third vaccination. It has been confirmed that a third vaccination restores the attenuation over time, of both the preventive effect against the Omicron variant and that against aggravation conferred by the first vaccination. Considering the current infection status, it is necessary to promote consideration of the first and third vaccinations at the earliest possible time.
    • Regarding vaccination of children (5-11 years old), the Immunization and Vaccine Section Meeting considered that it was appropriate to impose an obligation to make efforts to vaccinate children, as a certain level of knowledge has been acquired during the spread of the Omicron variant.
  2. 2. Use of tests
    • Based on the recommendations of the 17th meeting of the Novel Coronavirus Subcommittee, the national and local governments are required to secure a system that enables testing, and further utilize testing.
    • Frequent tests (about 2 or 3 times a week for facility workers) are required for workers at facilities for elderly people.
    • Depending on the circumstances in the area, testing at appropriate occasions is recommended for users of facilities for elderly people.
    • Depending on the circumstances in the area, if a cluster occurs it is necessary to carry out frequent testing of teachers and staff at nursery schools and kindergartens.
    • At the discretion of local governments and schools, it is necessary to thoroughly observe children’s health, and test those with any symptoms.
    • Preliminary testing is further recommended when having a meal with a large number of people or when interacting with elderly people.
    • Establishment of a self-testing system for fever outpatients should be further promoted, in which patients with symptoms can self-test using an antigen qualitative test kit, and if the result is positive, they can promptly undergo health observation at a health follow-up center, etc.
    • In order to promote these efforts, it is important for the government to provide a stable supply including distribution, by purchasing antigen qualitative test kits, distributing them to prefectural governments, and providing coordination support.
    • It is necessary to promote the utilization of medical antigen qualitative test kits as OTC.
  3. 3. Effective ventilation
    • Based on the recommendations of the 17th meeting of the Novel Coronavirus Subcommittee, it is necessary to publicize and recommend effective ventilation methods in the summer when ventilation becomes insufficient due to the use of air conditioners (how to create airflow considering aerosols, installation of partitions that do not block airflow, etc.).
  4. 4. Securing a medical care provision system
    • In preparation for further spread of infection, prefectural governments must take measures to avoid overcrowding of beds and fever outpatient sections with the support of the national government.
    • In addition to facilitating the use of available hospital beds and developing temporary medical facilities to supplement hospital beds, making efforts to avoid a shortage of hospital beds and emergency medical care, such as utilization of lodging facilities and resting beds
    • Making appropriate adjustments so that patients requiring inpatient treatment can be hospitalized preferentially, performing frequent tests at facilities for elderly people, etc., and further strengthening medical support
    • Securing and expanding logistical support hospitals, and improving the hospital turnover rate, such as by dissemination of the standard for early discharge of 4 days, as a rule
    • Promotion of effective and less burdensome measures against infection, such as flexible and efficient use of hospital beds through zoning of each hospital room
    • Establishment of a self-testing system for fever outpatients should be further promoted, in which patients with symptoms can self-test using an antigen qualitative test kit, and if the result is positive, they can promptly undergo health observation at a health follow-up center, etc.
    • Strengthening of the supply system of the antigen qualitative test kits, and understanding and publicizing the cases of home care without going through a fever outpatient section
    • Local residents should be informed that they should refrain from visiting an emergency outpatient unit only to receive a precautionary examination without symptoms, according to the actual situation in the region. In addition, in order to respond to concerns and questions at the time of worsening physical conditions, the consultation service by healthcare professionals via telephone should be thoroughly publicized, and this service should also be strengthened.
    • A system of appropriate and early administration of therapeutic drugs should be established and strengthened, such as publication of the registration status of therapeutic drugs in medical care/testing institutions.
    • Response to ambulance transport difficulties In addition to confirming the acceptance system for patients other than those with COVID-19, spreading awareness of heat stroke prevention and warning of increased emergency transportation due to heat stroke.
    • Ensuring that workplaces and schools do not require test certificates at the start of medical treatment
    • Further promote the reduction of burdens, such as hospitalization coordination and outsourcing/unification of operations by the hospitalization coordination division, so that public health center operations will not be strained.
    • Inspecting and securing oxygen administration systems for patients who temporarily need oxygen administration, such as securing oxygen concentrators, in view of the increase in the numbers of home care recipients and medical treatment adjustments, and medical care in facilities for elderly people.
  5. 5. Surveillance
    • Deterioration of the accuracy of current surveillance is a concern due to prioritization of notification items, delays in testing and diagnosis/reporting due to the spread of infection, and changes in healthcare-seeking behavior. It is necessary to promptly promote consideration of effective and appropriate surveillance to grasp the epidemic status. It is also necessary to continue monitoring the trends of variants through genomic surveillance.
  6. 6. Re-inspection and implementation of basic infection control
    • Re-inspection and implementation of the following basic infection control measures are needed.
    • Eating and drinking should be done with as few people as possible, and masks should be worn except while eating and drinking.
    • Continue proper wearing of nonwoven masks, hand hygiene, thorough ventilation, etc.
    • People with symptoms such as sore throat, cough, and fever should refrain from going out.
    • Avoid situations with a high risk of infection, such as the three Cs, congestion, or loud voices.
    • Refer to guidelines for hospital visits and use of an ambulance.
    • To reduce the chances of contact as far as possible, it is necessary for measures at the workplace, such as again promoting the use of telework.
    • Organizers of events, meetings, and such should fully evaluate the epidemic situation and risk of infection in the area, and consider whether or not to hold the meeting, and if it is held, measures should be taken to minimize the infection risk.
<< Reference: Findings on the characteristics of the Omicron variant and its sublineages >>
  1. [Infectivity/transmissibility]

    It has been confirmed that compared to the Delta variant, the generation time has shortened to approximately 2 days (approximately 5 days for Delta). The doubling time and incubation period have also shortened, the risk of re-infection and secondary infection after infection has increased, and the speed of infection spread is very fast. According to the reported data, pre-symptomatic transmission has probably occurred to some extent as with the previous strains.

  2. [Place/route of infection]

    In Japan, many cases of infection have occurred through the same opportunities as before (spending time indoors in locations with inadequate ventilation, eating and drinking, etc.), and infection is considered to have occurred via the same routes as before (droplets adhering to mucosa, aerosol inhalation, contact infection, etc.).

  3. [Severity]

    It has been suggested that infection with the Omicron variant presents a lower risk of hospitalization or aggravation than the Delta variant. However, analyses to date show that the fatality due to infection with the Omicron variant is higher than that due to seasonal influenza. It is also suggested that the incidence of pneumonia is higher than that of seasonal influenza, but given the limited data, it needs to be investigated by various analyses. The death toll from the previous outbreak compared to last summer's outbreak had a higher proportion of people aged 80 and over. It is reported that there are many cases in which the new coronavirus infection is not the direct cause of death, for example, people who have been in a facility for the elderly before the infection are infected and die due to the worsening of the underlying disease. Attention should also be paid to worsening of the condition of elderly infected people and infected people with an underlying disease, and to the onset of heart failure and aspiration pneumonia.

  4. [Duration of viral shedding]

    Viral shedding in individuals infected with the Omicron variant decreases over time. In patients with symptoms, it has been shown that the possibility of viral shedding is low from 10 days after the date of onset, and that no shedding is observed after 8 days from the date of diagnosis in those without symptoms.

  5. [Vaccine effect]

    For infection with the Omicron variant, the preventive effects of a first vaccination against infection and disease onset are markedly reduced. Its preventive effect on hospitalization is reported to be maintained at a certain level for the first 6 months, but subsequently decreases to 50% or less. On the other hand, it has been reported overseas that a third vaccination restores the infection-preventing effect, onset-preventing effect, and hospitalization-preventing effect against infection by the Omicron variant, and information on how these vaccine effects are attenuated after a third vaccination has become available. Regarding the fourth vaccination, it has been reported that while the preventive effect against aggravation was not reduced for 6 weeks, the preventive effect against infection lasted only for a short time.

  6. [Sublineages of the Omicron variant]

    Worldwide, the proportion of the BA.5 lineage is increasing while the number of positive cases increases, suggesting that this lineage is superior to the BA.2 lineage in terms of causing an increase in the number of infected people, but recently the number of positive cases has decreased. The BA.5 lineage has shown a tendency to escape existing immunity compared with the BA.1 and BA.2 lineages, but no clear findings on the infectivity have been shown. The effective reproduction number of the BA.5 lineage calculated based on the data of Tokyo was about 1.27 times that of BA.2. It was also estimated that it was about 1.3 times higher in samples collected from private testing institutions nationwide.

    According to the WHO report, the severity of BA.5 lineage shows both increased and unchanged data compared to the existing Omicron variants, and continued information collection is needed. In addition, the pathogenicity of the BA.5 lineage is reportedly higher than that of the BA.1 and BA.2 lineages, based on Japanese laboratory data, but it has not been confirmed clinically at this time. Although it is unknown whether it is due to the traits of the BA.5 lineage, it should be noted that the numbers of inpatient cases and severe cases are increasing in countries where the number of infected people is increasing mainly in the BA.5 lineage. According to genomic surveillance in Japan, the detection rate of the BA.5 lineage is increasing, and the previous dominant variant was replaced with this lineage.

    In addition, the BA.2.75 lineage, which has been reported mainly in India since June, has been detected in Japan. However, no clear findings have been obtained overseas regarding its infectivity or severity, compared with other lineages. It is necessary to continue to collect and analyze the situation and findings in other countries regarding these characteristics of the virus, and to continue monitoring by genome surveillance.

Figures (Number of new infections reported etc.) (PDF)

 

95th Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (August 18, 2022) Material 1

 

Evaluation of the latest infectious status, etc.

Overview of the infection status

  • The number of new cases of infection nationwide (based on the reporting dates) is approximately 1,036 per 100,000 population for the latest week, and the ratio to the previous week has decreased to 0.87. The number of infected persons is increasing in some regions, and the highest level of infection ever continues nationwide. On the other hand, in view of the severe pressure on the testing system, changing healthcare-seeking behavior, and the delay in the conduct of tests and examinations and the publication of reports during the summer vacations and Obon holidays; the infection status may still have been underestimated.
  • As the number of new cases of infection start to decrease, the number of patients receiving treatment is also starting to decrease. On the other hand, the use rate of beds is increasing or remains high nationwide. As for the medical care provision system, the increasing inability to provide smooth emergency transportation and the absence from work of healthcare workers have not improved, placing a significant burden not only on COVID-19 treatment, but also the medical care provision system in general. There is concern that the situation may deteriorate further.
    In addition, the numbers of severe cases and deaths are on the rise, and there is particular concern that the number of deaths may further increase to exceed the previous record-high.

    Effective reproduction number: On a national basis, the most recent number is 1.00 (as of July 31), while the figure stands at 0.99 both in the Tokyo metropolitan and Kansai areas.

Local trends

* The value for new cases of infection is the number of persons per 100,000 among the total number for the latest week, based on the reporting dates.

  1. Hokkaido

    The number of new cases of infection was approximately 856 (approximately 909 in Sapporo City), with a ratio to the previous week of 0.97. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 40%.

  2. North Kanto

    In Ibaraki, Tochigi, and Gunma, the numbers of new cases of infection were roughly 708, 656, and 755, with ratios to the previous week of 0.75, 0.73, and 0.84, respectively. In Ibaraki, Tochigi, and Gunma, they were mainly in their 30s or younger. The use rates of beds are slightly less than 60% in Ibaraki, slightly more than 60% in Tochigi, and slightly more than 50% in Gunma, respectively.

  3. Tokyo metropolitan area (Tokyo and 3 neighboring prefectures)

    The number of new cases of infection in Tokyo was approximately 1,240, with a ratio to the previous week of 0.82. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 60%, and the use rate of beds for severe patients is slightly more than 60%. In Saitama, Chiba, and Kanagawa, the numbers of new cases of infection were approximately 864, 698, and 772, with ratios to the previous week of 0.77, 0.69, and 0.77, respectively. The use rates of beds are slightly less than 70% in Saitama, slightly more than 60% in Chiba, and slightly more than 70% in Kanagawa, respectively.

  4. Chukyo/Tokai

    The number of new cases of infection in Aichi was approximately 1,102, with a ratio to the previous week of 0.82. The infected individuals are mainly in their 30s or younger. The use rate of beds is approximately 70%. In Gifu, Shizuoka, and Mie, the numbers of new cases of infection were roughly 1,095, 917, and 949, with ratios to the previous week of 0.95, 0.83, and 0.85, respectively. The use rates of beds are slightly more than 50% in Gifu, slightly less than 60% in Mie, and slightly more than 70% in Shizuoka.

  5. Kansai area

    The number of new cases of infection in Osaka was approximately 1,305, with a ratio to the previous week of 0.82. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 60%, while the use rate of beds for severe cases is roughly 50%. In Shiga, Kyoto, Hyogo, Nara, and Wakayama, the numbers of new cases of infection were roughly 1,096, 1,122, 1,179, 1,088, and 1,198, with ratios to the previous week of 0.89, 0.83, 0.86, 0.94, and 0.97, respectively. The use rates of beds are slightly more than 80% in Shiga, approximately 70% in Wakayama, approximately 60% in Kyoto, and slightly more than 60% in Hyogo and Nara, respectively.

  6. Kyushu

    The number of new cases of infection in Fukuoka was approximately 1,350, with a ratio to the previous week of 0.86. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 80%. In Saga, Nagasaki, Kumamoto, Oita, Miyazaki, and Kagoshima, the numbers of new cases of infection were approximately 1,470, 1,418, 1,273, 1,273, 1,581, and 1,578, with ratios to the previous week of 1.07, 1.04, 0.85, 1.06, 1.01, and 1.07, respectively. The use rates of beds are slightly more than 50% in Saga, Oita, and Miyazaki, slightly less than 60% in Nagasaki, approximately 70% in Kumamoto, and slightly more than 60% in Kagoshima.

  7. Okinawa

    The number of new cases of infection was the highest nationwide at approximately 1,753, with a ratio to the previous week of 0.80. The infected individuals are mainly in their 30s or younger. The use rate of beds is approximately 90%, while the use rate of beds for severe patients is slightly more than 30%.

  8. Areas other than above

    The ratio to the previous week in Yamagata, Yamaguchi, Tokushima, Kagawa, Ehime, and Kochi is 1.17, 1.15, 1.19, 1.15, 1.12, and 1.16, respectively. The use rates of beds are slightly more than 60% in Aomori, Okayama, and Hiroshima, approximately 60% in Niigata and Nagano, and approximately 70% in Ishikawa

Infection status and future outlook

Infection status
  • Concerning the number of new cases of infection, the effects of reducing the number of tests during the summer vacation and the Obon holidays, and voluntary care at home should be carefully monitored. The number of infected persons is taking a downward trend mainly in the Tokyo metropolitan area and it started to decrease nationwide, but is still at the highest level of infection ever. In addition, the number of infected persons is increasing in some regions, and there are some regions where the number once tended to decrease or remained high, where a rapid increase has been seen. In Okinawa, the infection is showing a downward trend but at a higher level than in other regions; medical care services are under much pressure. In addition, the number of “patients receiving treatment within facilities” has actually been increasing due to a rapid increase in mass infections at facilities for elderly people and shortages of beds. In addition, the rapid increase in cases of infection and close contacts nationwide is still affecting not only medical institutions and welfare facilities, but also social activities as a whole.
  • The number of new cases of infection in each age group started to decrease nationwide; the extent of decrease has become larger in young people, mainly in their teens, especially in summer vacation. On the other hand, as the trend was before, increases in the number of severe cases and deaths tend to lag behind the rapid increase in the number of new infections. The number of deaths in particular showed a rapid increase close to the peak level of the sixth wave, and there is concern that there will be a further increase in the number of deaths in the future that will exceed the previous record-high number.
  • Regarding the place of contracting new infections, the rate of infections that develop at home is still showing an increasing trend, with a decreasing trend at schools, due to the impact of the summer vacation. In addition, the percentage of people who contracted the infection at the office (workplace) increased among people in their 20s and decreased among those in their 30s to 60s. In addition, the percentage of people who contract it in the hospital is increasing among people in their 50s to 70s (it must be kept in mind that active epidemiological surveillance is focused on large cities, and that infection routes are not fully understood).
Future outlook and factors that increase and suppress infection
  • Regarding the future infection status, according to the epi curve of onset dates and the short-term forecasts for large cities, most regions are thought to have passed the peak, and in some areas the number of new infections has actually decreased, although the numbers are still rising or remaining high in quite a number of regions. Effects of movement of people during the Obon holidays is a concern. Much pressure on the medical care provision systems will continue unless the number of infected persons decreases early.
  • Factors that affect the number of infected individuals include: (1) the gradual diminishing of the immunity acquired by the third vaccination and infection, (2) possible increase in chances of contact during summer vacations, events and Obon, etc., and (3) the situation that the previously dominant variant has almost been replaced with the Omicron variant of BA.5 lineage.
  1. [Vaccination]

    It has become clear that as a certain period elapses after the third vaccination, the infection prevention effect is attenuated compared to the aggravation prevention effect. In addition, the immunity acquired from previous infections is expected to similarly decline in the future.

  2. [Contact patterns]

    The nighttime population curve generally remains flat. In large cities including the Tokyo metropolitan area and Okinawa, it has decreased or remained flat. There are also some regions where a rapid increase was seen in association with the holding of large festivals, etc.

  3. [Epidemic strain]

    After the prevalence of the BA.2 lineage, it has almost been replaced by the BA.5 lineage, which has become mainstream. The BA.5 lineage is thought to cause an increase the number of infected persons more easily, and there is concern about immune escape, which may be a factor to increase the number of infected persons.

  4. [Climatic factors]

    It is a time when indoor activities increase due to rising temperatures, but ventilation may be difficult because air conditioning is prioritized.

Status of the medical care provision system
  • Nationwide, the burden on the outpatient examination system is increasing, and the use rate of beds has increased or remains high nationwide, and regions with rates exceeding 50% are increasing. In particular, the rate exceeds 90% in Okinawa, which is under much pressure. The use rate of beds for severe patients now exceeds 50% in Tokyo and Osaka. On the other hand, the number of patients in home care and arranged accommodation for care are still showing an increasing trend in many regions. In some regions, the rate of increase started to slow down or the trend started to turn downward.
  • Sufficient manpower cannot be secured yet due to an increase in infections among healthcare professionals nationwide, including Okinawa. The burden on the medical care provision systems has persisted and includes general medical services. In the field of nursing care too, the difficult situation continues due to the increasing numbers of patients being treated in facilities and infection among workers.
  • The positive rate of the test remains high, complicating assessment. There is also concern whether the test is appropriately performed on those who need it, such as people with symptoms.
  • Although the increased burden on emergency transportation has generally slowed down, such cases have increased in some regions and caution should be paid to them. In addition, careful attention should be paid to the increase in cases of ambulance transportation due to the effects of the continuing hot weather.

Measures to be taken

Basic concepts
  • In the midst of the spread of infection, it is necessary to reduce, as much as possible the chances of contacts that risk infection, based on the various knowledge that Japanese society has already learned. Also, in order to maintain socio-economic activities, it is necessary to work on methods for people to avoid infecting and being infected.
  • To this end, the national and local governments will remind the public of the need for routine infection control measures, and take measures to support the public's efforts to prevent infection. In addition, efforts must be made to reduce the number of infected people so as not to increase the numbers of severe cases and deaths, as much as possible. Furthermore, further efforts should be made to reinforce the medical care provision system, and reduce the burdens on medical institutions and public health centers.
  1. 1. Further promotion of vaccinations
    • In a case-control study investigating the efficacy of the SAR-CoV-2 vaccine in Japan, the prophylactic effect against the disease at 5 months after the second vaccination was low compared to unvaccinated cases in the epidemic period of BA.5. On the other hand, 3 doses of vaccination (booster) were shown to possibly increase the prophylactic effect against the disease to a moderate to high degree. It was preliminarily reported that the relative efficacy rate of 3 doses of vaccination compared with 2 doses can be expected to a certain extent.
    • Regarding the booster vaccination with "vaccine for the Omicron variant," it will be prepared for use after the middle of October this year, targeting those who have completed the initial vaccination.
    • For the fourth vaccination, it is necessary to continue efforts to provide earlier vaccination for eligible persons (elderly people aged 60 years and older, and those aged less than 60 years at risk for severe illness, etc.) for prophylaxis against exacerbation. Considering the ongoing spread of infection, workers at medical institutions, facilities for elderly people, etc. where many individuals who are at high risk of becoming severely ill gather, have also been included in those who are eligible for vaccination.
    • Vaccination with recombinant protein may be selected for up to the third vaccination. It has been confirmed that a third vaccination restores the attenuation over time, of both the preventive effect against the Omicron variant and that against aggravation conferred by the first vaccination. Considering the current infection status, it is necessary to promote consideration of the first and third vaccinations at the earliest possible time.
    • Regarding vaccination of children (5-11 years old), the Immunization and Vaccine Section Meeting considered that it was appropriate to impose an obligation to make efforts to vaccinate children, as a certain level of knowledge has been acquired during the spread of the Omicron variant.
  2. 2. Use of tests
    • Based on the recommendations of the 17th meeting of the Novel Coronavirus Subcommittee, the national and local governments are required to secure a system that enables testing, and further utilize testing.

    1. [The Elderly]
      • Frequent tests (about 2 or 3 times a week for facility workers) are required for workers at facilities for the elderly.
      • Depending on the circumstances in the area, testing at appropriate occasions is recommended for users of facilities for elderly people.
    2. [Children]
      • Depending on the circumstances in the area, if a cluster occurs it is necessary to carry out frequent testing of teachers and staff at nursery schools and kindergartens.
      • At the discretion of local governments and schools, it is necessary to thoroughly observe health, test those with some symptoms, and prevent outbreaks while allowing participation in club activities such as tournaments and school trips.
    3. [Young people]
      • Preliminary testing is further recommended when having a meal with a large number of people or when interacting with elderly people.
      • Establishment of a self-testing system for fever outpatients should be further promoted, in which patients with symptoms can self-test using an antigen qualitative test kit, and if the result is positive, they can promptly undergo health observation at a health follow-up center, etc.
      • In order to promote these efforts, it is important for the government to provide a stable supply including distribution, by purchasing antigen qualitative test kits, distributing them to prefectural governments, and providing coordination support.
  3. 3. Effective ventilation
    • Based on the recommendations of the 17th meeting of the Novel Coronavirus Subcommittee, it is necessary to publicize and recommend effective ventilation methods in the summer when ventilation becomes insufficient due to the use of air conditioners (how to create airflow considering aerosols, installation of partitions that do not block airflow, etc.).
  4. 4. Securing a medical care provision system
    • In preparation for further spread of infection, prefectural governments must take measures to avoid overcrowding of beds and fever outpatient sections with the support of the national government.
    • Immediate responses such as securing beds, and the development of temporary medical facilities that play the role of supplementing hospital beds
    • Making appropriate adjustments so that patients requiring inpatient treatment can be hospitalized preferentially, performing frequent tests at facilities for elderly people, etc., and further strengthening medical support
    • Securing and expanding logistical support hospitals, and improving the hospital turnover rate, such as by dissemination of the standard for early discharge of 4 days, as a rule
    • Promotion of effective and less burdensome measures against infection, such as flexible and efficient use of hospital beds through zoning of each hospital room
    • Establishment of a self-testing system for fever outpatients should be further promoted, in which patients with symptoms can self-test using an antigen qualitative test kit, and if the result is positive, they can promptly undergo health observation at a health follow-up center, etc.
    • Strengthening of the supply system of the antigen qualitative test kits, and understanding and publicizing the cases of home care without going through a fever outpatient section
    • Local residents should be informed that they should refrain from visiting an emergency outpatient unit only to receive a precautionary examination without symptoms, according to the actual situation in the region. In addition, in order to respond to concerns and questions at the time of worsening physical conditions, the consultation service by healthcare professionals via telephone should be thoroughly publicized, and this service should also be strengthened.
    • A system of appropriate and early administration of therapeutic drugs should be established and strengthened, such as publication of the registration status of therapeutic drugs in medical care/testing institutions.
    • Response to the increasing trend of ambulance transport difficulties. In addition to confirming the acceptance system for patients other than those with COVID-19, spreading awareness of heat stroke prevention and warning of increased emergency transportation due to heat stroke.
    • Ensuring that workplaces and schools do not require test certificates at the start of medical treatment
    • Further promote the reduction of burdens, such as hospitalization coordination and outsourcing/unification of operations by the hospitalization coordination division, so that public health center operations will not be strained.
  5. 5. Surveillance
    • Deterioration of the accuracy of current surveillance is a concern due to prioritization of notification items, delays in testing and diagnosis/reporting due to the spread of infection, and changes in healthcare-seeking behavior. It is necessary to promptly promote consideration of effective and appropriate surveillance to grasp the epidemic status. It is also necessary to continue monitoring the trends of variants through genomic surveillance.
  6. 6. Re-inspection and implementation of basic infection control
    • Re-inspection and implementation of the following basic infection control measures are needed.
    • Continue proper wearing of nonwoven masks, hand hygiene, thorough ventilation, etc.
    • People with symptoms such as a sore throat, cough, and fever should refrain from going out.
    • Avoid situations with a high risk of infection, such as the three Cs, congestion, or loud voices.
    • Refer to guidelines for hospital visits and use of an ambulance.
    • Eating and drinking should be done with as few people as possible, and masks should be worn except while eating and drinking.
    • To reduce the chances of contact as far as possible, it is necessary for measures at the workplace, such as again promoting the use of telework.
    • Organizers of events, meetings, and such should fully evaluate the epidemic situation and risk of infection in the area, and consider whether or not to hold the meeting, and if it is held, measures should be taken to minimize the infection risk.
<< Reference: Findings on the characteristics of the Omicron variant and its sublineages >>
  1. [Infectivity/transmissibility]

    It has been confirmed that compared to the Delta variant, the generation time has shortened to approximately 2 days (approximately 5 days for Delta). The doubling time and incubation period have also shortened, the risk of re-infection and secondary infection after infection has increased, and the speed of infection spread is very fast. According to the reported data, pre-symptomatic transmission has probably occurred to some extent as with the previous strains.

  2. [Place/route of infection]

    In Japan, many cases of infection have occurred through the same opportunities as before (spending time indoors in locations with inadequate ventilation, eating and drinking, etc.), and infection is considered to have occurred via the same routes as before (droplets adhering to mucosa, aerosol inhalation, contact infection, etc.).

  3. [Severity]

    It has been suggested that infection with the Omicron variant presents a lower risk of hospitalization or aggravation than the Delta variant. However, analyses to date show that the fatality due to infection with the Omicron variant is higher than that due to seasonal influenza. It is also suggested that the incidence of pneumonia is higher than that of seasonal influenza, but given the limited data, it needs to be investigated by various analyses. The death toll from the previous outbreak compared to last summer's outbreak had a higher proportion of people aged 80 and over. It is reported that there are many cases in which the new coronavirus infection is not the direct cause of death, for example, people who have been in a facility for the elderly before the infection are infected and die due to the worsening of the underlying disease. Attention should also be paid to worsening of the condition of elderly infected people and infected people with an underlying disease, and to the onset of heart failure and aspiration pneumonia.

  4. [Duration of viral shedding]

    Viral shedding in individuals infected with the Omicron variant decreases over time. In patients with symptoms, it has been shown that the possibility of viral shedding is low from 10 days after the date of onset, and that no shedding is observed after 8 days from the date of diagnosis in those without symptoms.

  5. [Vaccine effect]

    For infection with the Omicron variant, the preventive effects of a first vaccination against infection and disease onset are markedly reduced. Its preventive effect on hospitalization is reported to be maintained at a certain level for the first 6 months, but subsequently decreases to 50% or less. On the other hand, it has been reported overseas that a third vaccination restores the infection-preventing effect, onset-preventing effect, and hospitalization-preventing effect against infection by the Omicron variant, and information on how these vaccine effects are attenuated after a third vaccination has become available. Regarding the fourth vaccination, it has been reported that while the preventive effect against aggravation was not reduced for 6 weeks, the preventive effect against infection lasted only for a short time.

  6. [Omicron variant sublineages]

    Worldwide, the proportion of the BA.5 lineage is increasing, suggesting that this lineage is superior to the BA.2 lineage in terms of causing an increase in the number of infected people. The number of positive tests is on the rise globally, as replacement by the BA.5 lineage proceeds. The BA.5 lineage has shown a tendency to escape existing immunity compared with the BA.1 and BA.2 lineages, but no clear findings on the infectivity have been shown. The effective reproduction number of the BA.5 lineage calculated based on the data of Tokyo was about 1.27 times that of BA.2. It was also estimated that it was about 1.3 times higher in samples collected from private testing institutions nationwide.

    According to the WHO report, the findings accumulated from multiple countries indicate that there is no increase in the severity of the BA.5 lineage compared to existing Omicron variants. On the other hand, the pathogenicity of the BA.5 lineage is reportedly higher than that of the BA.1 and BA.2 lineages, based on Japanese laboratory data, but it has not been confirmed clinically at this time. Although it is unknown whether it is due to the traits of the BA.5 lineage, it should be noted that the numbers of inpatient cases and severe cases are increasing in countries where the number of infected people is increasing mainly in the BA.5 lineage. According to genomic surveillance in Japan, the detection rate of the BA.5 lineage is increasing, and the previous dominant variant was replaced with this lineage.

    In addition, the BA.2.75 lineage, which has been reported mainly in India since June, has been detected in Japan. However, no clear findings have been obtained overseas regarding its infectivity or severity, compared with other lineages. It is necessary to continue to collect and analyze the situation and findings in other countries regarding these characteristics of the virus, and to continue monitoring by genome surveillance.

Figures (Number of new infections reported etc.) (PDF)

 

94th Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (August 10, 2022) Material 1

 

Evaluation of the latest infection status, etc.

Overview of the infection status

  • Nationwide, the number of new cases of infection (by date of report) was roughly 1,194 per 100,000 in the last week, with a ratio to the previous week of 1.05, and while the rate of increase has decreased, the number of infections continues to increase. Although the ratio to the previous week has remained below 1 in some regions, the country continues to experience its highest infection levels ever.
  • As the number of new cases of infection increases, the number of patients receiving medical treatment is continuing to increase, and the use rate of beds is continuing to rise almost nationwide. As for the medical care provision system, increased numbers of cases of difficult emergency transportation and absences of healthcare professionals from work have placed a significant burden not only on treatment for COVID-19, but also on the medical care provision system, including general medical care. There are concerns that the situation will deteriorate further.
    In addition, the numbers of severe cases and deaths continue to increase, and attention should be paid to future trends.

    Effective reproduction number: On a national basis, the most recent number is above 1 (1.03 as of July 24), while the figure stands at 1.01 in the Tokyo metropolitan area and 1.03 in the Kansai area.

Local trends

* The value for new cases of infection is the number of persons per 100,000 among the total number for the latest week, based on the reporting dates.

  1. Hokkaido

    The number of new cases of infection was approximately 865 (roughly 1021 in Sapporo City), with a ratio to the previous week of 1.15. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 30%.

  2. North Kanto

    In Ibaraki, Tochigi, and Gunma, the numbers of new cases of infection were roughly 982, 912, and 885, with ratios to the previous week of 1.25, 1.05, and 1.09, respectively. In Ibaraki, Tochigi, and Gunma, they were mainly in their 30s or younger. The use rates of beds are slightly more than 60% in Ibaraki, approximately 60% in Tochigi, and slightly less than 60% in Gunma.

  3. Tokyo metropolitan area (Tokyo and 3 neighboring prefectures)

    The number of new cases of infection in Tokyo was approximately 1,540, with a ratio to the previous week of 0.97. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 50%, while the use rate of beds for severe cases is slightly more than 60%. In Saitama, Chiba, and Kanagawa, the numbers of new cases of infection were roughly 1,135, 1,038, and 1,037, with ratios to the previous week of 1.01, 1.00, and 0.94, respectively. The use rates of beds are slightly less than 70% in Saitama, slightly more than 90% in Chiba, and approximately 80% in Kanagawa.

  4. Chukyo/Tokai

    The number of new cases of infection in Aichi was approximately 1,324, with a ratio to the previous week of 1.07. The infected individuals are mainly in their 30s or younger. The use rate of beds is approximately 80%. In Gifu, Shizuoka, and Mie, the numbers of new cases of infection were roughly 1,133, 1,106, and 1,104, with ratios to the previous week of 1.20, 1.19, and 1.17, respectively. The use rate of beds is slightly less than 60% in Gifu and Mie, and slightly more than 80% in Shizuoka.

  5. Kansai area

    The number of new cases of infection in Osaka was approximately 1,596, with a ratio to the previous week of 1.01. The infected individuals are mainly in their 30s or younger. The use rate of beds is approximately 70%, while the use rate of beds for severe patients is slightly more than 40%. In Shiga, Kyoto, Hyogo, Nara, and Wakayama, the numbers of new cases of infection were roughly 1,202, 1,370, 1,347, 1,116, and 1,227, with ratios to the previous week of 1.02, 1.03, 1.09, 1.09, and 1.30, respectively. The use rates of beds are slightly more than 70% in Shiga and Wakayama, roughly 50% in Kyoto, and slightly more than 60% in Hyogo and Nara.

  6. Kyushu

    The number of new cases of infection in Fukuoka was approximately 1,577, with a ratio to the previous week of 0.97. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 70%. In Saga, Nagasaki, Kumamoto, Oita, Miyazaki, and Kagoshima, the numbers of new cases of infection were about 1,344, 1,302, 1,504, 1,201, 1,553, and 1,441, with ratios to the previous week of 1.04, 1.24, 1.03, 1.09, 1.15, and 1.05, respectively. The use rates of beds are roughly 50% in Saga and Oita, slightly more than 60% in Nagasaki, slightly less than 70% in Kumamoto, slightly less than 50% in Miyazaki, and slightly more than 70% in Kagoshima.

  7. Okinawa

    The number of new cases of infection was the highest nationwide at approximately 2,262, with a ratio to the previous week of 0.96. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 80%, while the use rate of beds for severe cases is slightly more than 30%.

  8. Areas other than the above

    Aomori, Niigata, Fukui, Shimane, Hiroshima, and Kochi had ratios to the previous week of 0.95, 1.12, 0.94, 1.16, 1.41, and 1.36, respectively. The number of new cases of infection was approximately 908 in Shimane. The use rates of beds are slightly more than 50% in Aomori, slightly more than 70% in Niigata, and slightly more than 60% in Ishikawa, Okayama, and Hiroshima.

Infection status and future outlook

Infection status
  • Although the ratio to the previous week was below 1 in some regions, the number of new cases has greatly exceeded the previous spread of infection in all prefectures, and Japan is continuing to experience its highest infection levels ever. The infection level in Okinawa continues to be higher than in other regions, while the use rate of beds is also severe. In addition, the number of “patients receiving treatment within facilities” has actually been increasing due to a rapid increase of mass infections at facilities for the elderly and shortages of beds. In addition, the rapid increase in cases of infection and close contacts nationwide is affecting not only medical institutions and welfare facilities, but also social activities as a whole.
  • The number of new infections nationwide by age group started to decrease in young people, mainly among teenagers during the summer vacation, but continues to increase in individuals in their 50s and older, including the elderly, who are at a high risk of aggravation. As in the previous trends, an increase in the number of severe cases and deaths has tended to lag behind a rapid increase in the number of new infections. The number of deaths especially showed a rapid increase close to the peak level of the sixth wave, and there are concerns that there will be a further increase in the number of deaths in the future.
  • Regarding the future infection status, according to the epi curve of onset dates and the short-term forecasts for large cities, most regions are thought to have passed the peak, and in some areas the number of new infections has actually decreased, although the numbers are still rising in most regions. In addition, there are some regions where the number once tended to decrease or remained high, which have seen a rapid increase. The increase may be attributable to the impact of increased opportunities for social contact due to the summer vacation and events. There are concerns regarding the impact of the flow of people during the coming Obon holiday. Therefore, it is necessary to pay careful attention with the utmost vigilance, including regarding the effects on the medical care provision system.
  • Factors in the continued increase in the number of infected individuals include: (1) the gradual diminishing of the immunity acquired by the third vaccination and infection, (2) the increased contact that is expected due to the influence of the summer vacation and Obon, etc., and (3) the presumed replacement of the Omicron variant by lineages such as BA.5.
  • Regarding the places of new infections, home is showing an increasing trend, with a decreasing trend at schools, due to the impact of the summer vacation. In addition, the percentage of offices (workplaces) is increasing among people in their 20s to 60s (it must be kept in mind that active epidemiological surveillance is focused on large cities, and that infection routes are not fully understood).
Factors that increase and suppress infection
  1. It is thought that the infection status is affected by the following changes in factors that increase and suppress infection.

  1. [Vaccination]

    It has become clear that as a certain period elapses after the third vaccination, the infection prevention effect is attenuated, compared to the aggravation prevention effect. In addition, the immunity acquired from previous infections is expected to similarly decline in the future.

  2. [Contact patterns]

    The nighttime population is flat, overall. In the Tokyo metropolitan area, Chubu area, Kansai area, and Okinawa, it has decreased or remained flat. In addition, the summer vacation at schools, etc. may have contributed to the decrease in the number of newly infected young people, mainly in their teens.

  3. [Epidemic strain]

    After the prevalence of BA.2 lineage, it is estimated that the BA.5 lineage will become mainstream and replace it. The BA.5 lineage is thought to increase the number of infected persons more easily, and there are concerns regarding immune escape, which may be a factor in increasing the number of infected persons.

  4. [Climatic factors]

    It is a time when indoor activities increase due to rising temperatures, but ventilation may be difficult because air conditioning is prioritized.

Status of medical care provision system
  • Nationwide, the burden on the outpatient examination system is increasing, and the use rate of beds is continuing to increase almost nationwide, exceeding 50% in many regions. Particularly in Chiba, Kanagawa, Shizuoka, Aichi, and Okinawa, the rate now exceeds 80%, and the situation is difficult. The use rate of beds for severe patients now exceeds 50% in some regions. In addition, the numbers of home care recipients and medical treatment adjustments are increasing continuously in most regions, and are increasing rapidly in some regions.
  • Across Japan including Okinawa, an increase in infections among healthcare professionals has been placing a burden on the medical care provision system. In the field of nursing care also, the difficult situation continues due to the increasing numbers of patients being treated in facilities and of infections among workers.
  • Positive test rates have remained high, and there are concerns regarding whether the tests are being appropriately received by those who need them, such as persons with symptoms.
  • Regarding cases of difficult ambulance transport, the numbers of both suspected non-COVID-19 cases and suspected COVID-19 cases continue to increase in many areas. However, the number of incidents has peaked in some areas, although the number of infections is increasing, and a thorough analysis is needed. In addition, as hot weather continues, careful attention should be paid to the increase in ambulance transportation due to heat stroke.

Measures to be taken

Basic concepts
  • In the midst of the spread of infection, it is necessary to reduce, as much as possible the chances of contacts that risk infection, based on the various knowledge that Japanese society has already learned. Also, in order to maintain socio-economic activities, it is necessary to work on methods for people to avoid infecting and being infected.
  • To this end, the national and local governments will remind the public of the need for routine infection control measures and take measures to support the public's efforts to prevent infection. In addition, efforts must be made to reduce the number of infected people so as not to increase the numbers of severe cases and deaths, as much as possible. Furthermore, further efforts should be made to reinforce the medical care provision system and reduce the burdens on medical institutions and public health centers.
  1. 1. Further promotion of vaccination
    • Regarding the booster vaccination with "vaccine for the Omicron variant," it is necessary to make preparations for implementation after the middle of October this year, targeting those who have completed the initial vaccination.
    • The fourth vaccination has been rolled out at facilities for the elderly, etc. to prevent aggravation. It is necessary to continue efforts to provide earlier vaccination for eligible persons (the elderly aged 60 years and older, and those aged less than 60 years at risk of severe illness, etc.). Considering the ongoing spread of infection, workers at medical institutions, facilities for the elderly, etc. where many individuals who are at high risk of becoming severely ill gather, have also been included in those who are eligible for vaccination.
    • It has been confirmed that a third vaccination restores the attenuation over time, of both the preventive effect against the Omicron variant and that against aggravation conferred by the first vaccination. Considering the current infection status, it is necessary to promote consideration of the first and third vaccinations at the earliest possible time.
    • Regarding vaccinations in children (5-11 years old), the Immunization and Vaccine Section Meeting considered that it was appropriate to impose an obligation to make efforts toward vaccinations in children, as a certain level of knowledge has been acquired during the spread of the Omicron variant.
  2. 2. Use of tests
    1. Based on the recommendations of the 17th meeting of the Novel Coronavirus Subcommittee, the national and local governments are required to secure a system that enables testing, and further utilize testing.

    2. [The Elderly]
      • Frequent tests (about 2 or 3 times a week for facility workers) are required for workers at facilities for the elderly.
      • Depending on the circumstances in the area, testing at appropriate occasions (e.g. Obon, when contact with relatives who have returned home is expected) is recommended for users of facilities for the elderly.
    3. [Children]
      • Depending on the circumstances in the area, if a cluster occurs it is necessary to carry out frequent testing of teachers and staff at nursery schools and kindergartens.
      • At the discretion of local governments and schools, it is necessary to thoroughly observe health, test those with some symptoms, and prevent outbreaks while allowing participation in club activities such as tournaments and school trips.
    4. [Young people]
      • Preliminary testing is further recommended when having a meal with a large number of people or when interacting with the elderly (especially when contacting them during the Obon/summer vacation homecoming).
      • Establishment of a self-testing system for fever outpatients should be further promoted, in which patients with symptoms can self-test using an antigen qualitative test kit, and if the result is positive, they can promptly undergo health observation at a health follow-up center, etc.
      • In order to promote these efforts, it is important for the government to provide a stable supply including distribution, by purchasing antigen qualitative test kits, distributing them to prefectural governments, and providing coordination support.
  3. 3. Effective ventilation
    • Based on the recommendations of the 17th meeting of the Novel Coronavirus Subcommittee, it is necessary to publicize and recommend effective ventilation methods in the summer when ventilation becomes insufficient due to the use of air conditioners (how to create airflow considering aerosols, installation of partitions that do not block airflow, etc.).
  4. 4. Securing a medical care provision system
    • In preparation for further spread of infection, prefectural governments must take measures to avoid overcrowding of beds and fever outpatient sections with the support of the national government.
    • Immediate responses such as securing beds, and the development of temporary medical facilities that play the role of supplementing hospital beds
    • Making appropriate adjustments so that patients requiring inpatient treatment can be hospitalized preferentially, performing frequent tests at facilities for the elderly, etc., and further strengthening medical support
    • Securing and expanding logistical support hospitals, and improving the hospital turnover rate, such as by dissemination of the standard for early discharge of 4 days, as a rule
    • Promotion of effective and less burdensome measures against infection, such as flexible and efficient use of hospital beds through zoning for each hospital room
    • Establishment of a self-testing system for fever outpatients should be further promoted, in which patients with symptoms can self-test using an antigen qualitative test kit, and if the result is positive, they can promptly undergo health observation at a health follow-up center, etc.
    • Strengthening of the supply system of the antigen qualitative test kits, and understanding and publicizing the cases of home care without going through a fever outpatient section
    • Local residents should be informed that they should refrain from visiting an emergency outpatient unit only to receive a precautionary examination without symptoms, according to the actual situation in the region. In addition, in order to respond to concerns and questions at the time of worsening physical conditions, the consultation service by healthcare professionals via telephone should be thoroughly publicized, and this service should also be strengthened.
    • Establishing and strengthening a system that enables appropriate and early administration of therapeutic drugs
    • Response to the increasing trend of ambulance transport difficulties. In addition to confirming the acceptance system for patients other than COVID-19 patients, spreading awareness of heat stroke prevention and warning of increased emergency transportation due to heat stroke.
    • Ensuring that workplaces and schools do not require test certificates at the start of medical treatment
    • Further promote the reduction of burdens, such as hospitalization coordination and outsourcing/unification of operations by the hospitalization coordination division, so that public health center operations will not be strained.
  5. 5. Surveillance
    • It is necessary to promptly consider effective and appropriate surveillance, in order to properly grasp trends regarding occurrences. In addition, it is necessary to continue monitoring the trends of variants through genomic surveillance.
  6. 6. Re-inspection and implementation of basic infection control

    Re-inspection and implementation of the following basic infection control measures are needed.

    • Continue the proper wearing of nonwoven masks, hand hygiene, thorough ventilation, etc.
    • Persons with symptoms such as sore throat, cough, and fever should refrain from going out.
    • Avoid situations with a high risk of infection, such as the three Cs, crowds, and loud voices.
    • Refer to guidelines for hospital visits and use of ambulances.
    • Eating and drinking should be carried out with as few people as possible, and masks should be worn except while eating and drinking.
    • In order to reduce the chances of contact to the extent possible, it is necessary to take measures such as again promoting the use of telework at workplaces.
    • Organizers of events, meetings, and such should fully evaluate the epidemic situation and risk of infection in the area, and consider whether or not to hold the meeting, and if it is held, measures should be taken to minimize the infection risk.
<< Reference: Findings on the characteristics of the Omicron variant and its sublineages >>
  1. [Infectivity/transmissibility]

    It has been confirmed that compared to the Delta variant, the generation time has shortened to approximately 2 days (approximately 5 days for Delta). The doubling time and incubation period have also shortened, the risk of re-infection and secondary infection after infection has increased, and the speed of infection spread is very fast. According to the reported data, pre-symptomatic transmission has probably occurred to some extent as with the previous strains.

  2. [Place/route of infection]

    In Japan, many cases of infection have occurred through the same opportunities as before (spending time indoors in locations with inadequate ventilation, eating and drinking, etc.), and infection is considered to have occurred via the same routes as before (droplets adhering to mucosa, aerosol inhalation, contact infection, etc.).

  3. [Severity]

    It has been suggested that infection with the Omicron variant presents a lower risk of hospitalization or aggravation than the Delta variant. However, analyses to date show that the fatality due to infection with the Omicron variant is higher than that due to seasonal influenza. It is also suggested that the incidence of pneumonia is higher than that of seasonal influenza, but given the limited data, it needs to be investigated by various analyses. The death toll from the previous outbreak compared to last summer's outbreak had a higher proportion of people aged 80 and over. It is reported that there are many cases in which the new coronavirus infection is not the direct cause of death, for example, people who have been in a facility for the elderly before the infection are infected and die due to the worsening of the underlying disease. Attention should also be paid to worsening of the condition of elderly infected people and infected people with an underlying disease, and to the onset of heart failure and aspiration pneumonia.

  4. [Duration of viral shedding]

    Viral shedding in individuals infected with the Omicron variant decreases over time. In patients with symptoms, it has been shown that the possibility of viral shedding is low from 10 days after the date of onset, and that no shedding is observed after 8 days from the date of diagnosis in those without symptoms.

  5. [Vaccine effect]

    For infection with the Omicron variant, the preventive effects of a first vaccination against infection and disease onset are markedly reduced. Its preventive effect on hospitalization is reported to be maintained at a certain level for the first 6 months, but subsequently decreases to 50% or less. On the other hand, it has been reported overseas that a third vaccination restores the infection-preventing effect, onset-preventing effect, and hospitalization-preventing effect against infection by the Omicron variant, as well as information regarding how these vaccine effects are attenuated after a third vaccination. Regarding the fourth vaccination, while the preventive effect against aggravation was not reduced for 6 weeks, the preventive effect against infection was limited, and it was reported that the effect lasted only for a short time.

  6. [Omicron variant sublineages]

    Worldwide, the proportion of the BA.5 lineage is increasing, suggesting that this lineage is superior to the BA.2 lineage in terms of increasing the number of infected people. The number of positive tests is on the rise globally, as replacement by the BA.5 lineage proceeds.
    The BA.5 lineage has shown a tendency to escape existing immunity compared with the BA.1 and BA.2 lineages, but no clear findings on the infectivity have been shown. The effective reproduction number of the BA.5 lineage calculated based on the data of Tokyo was about 1.27 times that of BA.2. It was also estimated that it was about 1.3 times higher in samples collected from private testing institutions nationwide.

    According to the WHO report, the findings accumulated from multiple countries indicate that there is no increase in the severity of the BA.5 lineage compared to existing Omicron variants. On the other hand, the pathogenicity of the BA.5 lineage is reportedly higher than that of the BA.1 and BA.2 lineages, based on Japanese laboratory data, but it has not been confirmed clinically at this time. Although it is unknown whether it is due to the traits of the BA.5 lineage, it should be noted that the numbers of inpatient cases and severe cases are increasing in countries where the number of infected people is increasing mainly in the BA.5 lineage. According to genomic surveillance in Japan, the detection rate of the BA.5 lineage is increasing, and replacement has presumably progressed.

    In addition, the BA.2.75 lineage, which has been reported mainly in India since June, has been detected in Japan. However, no clear findings have been obtained overseas regarding its infectivity or severity, compared with other lineages. It is necessary to continue to collect and analyze the situation and findings in other countries regarding these characteristics of the virus, and to continue monitoring by genome surveillance.

Figures (Number of new infections reported etc.) (PDF)

 

93rd Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (August 3, 2022) Material 1

 

Overview of infection status

Overview of infection status

  • Nationwide, the number of new cases of infection (by date of report) was about 1,137 per 100,000 in the last week, with a ratio to last week of 1.16, and while the rate of increase has decreased, the number of infections continues to increase. It is again the highest level of infection ever in Japan.
  • As the number of new cases of infection increases, the number of patients receiving medical treatment continues to increase, and the use rate of beds continues to rise almost nationwide, and putting a heavy burden on the medical care provision system. In addition, the numbers of severe cases and deaths continue to increase, and attention should be paid to future trends.

    Effective reproduction number: On a national basis, the most recent number is above 1 (1.17 as of July 17), while the figure stands at 1.16 in the Tokyo metropolitan area and 1.19 in the Kansai area.

Local trends

* The value for new cases of infection is the number of persons per 100,000 among the total number for the latest week, based on reporting dates.

  1. Hokkaido

    The number of new cases of infection was approximately 753 (about 920 in Sapporo City), with a ratio to the previous week of 1.52. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 30%.

  2. North Kanto

    In Ibaraki, Tochigi, and Gunma, the numbers of new cases of infection were about 788, 871, and 814, with ratios to the previous week of 1.49, 1.28, and 1.18, respectively. In Ibaraki, Tochigi, and Gunma, they were mainly in their 30s or younger. The use rates of beds are slightly more than 40% in Ibaraki, slightly more than 50% in Tochigi, and slightly less than 50% in Gunma.

  3. Tokyo metropolitan area (Tokyo and 3 neighboring prefectures)

    The number of new cases of infection in Tokyo was approximately 1,595, with a ratio to the previous week of 1.11. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 50%, while the use rate of beds for severe cases is slightly more than 50%. In Saitama, Chiba, and Kanagawa, the numbers of new cases of infection were about 1,125, 1,039, and 1,106, with ratios to the previous week of 1.21, 1.17, and 1.26, respectively. The use rates of beds are slightly more than 60% in Saitama, slightly less than 60% in Chiba, and slightly more than 80% in Kanagawa.

  4. Chukyo/Tokai

    The number of new cases of infection in Aichi was approximately 1,240, with a ratio to the previous week of 1.10. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 60%. In Gifu, Shizuoka, and Mie, the numbers of new cases of infection were about 947, 932, and 944, with ratios to the previous week of 1.25, 1.05, and 1.29, respectively. The use rates of beds are slightly less than 50% in Gifu, slightly more than 40% in Mie, and slightly more than 70% in Shizuoka.

  5. Kansai area

    The number of new cases of infection in Osaka was approximately 1,576, with a ratio to the previous week of 1.01. The infected individuals are mainly in their 30s or younger. The use rate of beds is approximately 60%, while the use rate of beds for severe cases is slightly less than 40%. In Shiga, Kyoto, Hyogo, Nara, and Wakayama, the numbers of new cases of infection were about 1,178, 1,334, 1,238, 1,020, and 944, with ratios to the previous week of 1.64, 1.29, 1.17, 1.24, and 1.22, respectively. The use rates of beds are slightly more than 60% in Shiga, slightly less than 50% in Kyoto, approximately 60% in Hyogo, slightly less than 60% in Nara, and slightly more than 70% in Wakayama.

  6. Kyushu

    The number of new cases of infection in Fukuoka was approximately 1,623, with a ratio to the previous week of 1.10. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 80%. In Saga, Nagasaki, Kumamoto, Oita, Miyazaki, and Kagoshima, the numbers of new cases of infection were about 1,292, 1,053, 1,464, 1,099, 1,351, and 1,367, with ratios to the previous week of 1.05, 1.26, 1.00, 1.04, 1.23, and 1.21, respectively. The use rates of beds are slightly more than 50% in Saga and Nagasaki, slightly more than 60% in Kumamoto, approximately 50% in Oita, slightly more than 40% in Miyazaki, and slightly less than 80% in Kagoshima.

  7. Okinawa

    The number of new cases of infection was the highest nationwide at approximately 2,353, with a ratio of this week to last week of 1.04. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 70%, while the use rate of beds for severe cases is slightly more than 40%.

  8. Areas other than the above

    Aomori, Niigata, Fukui, Shimane, Okayama, and Hiroshima had ratios to the previous week of 0.97, 1.54, 1.61, 0.81, 1.39, and 1.35, respectively. The number of new cases of infection was approximately 785 in Shimane. The use rates of beds are slightly more than 50% in Aomori and Kochi, slightly less than 60% in Niigata, and slightly more than 60% in Hiroshima.

Infection status and future outlook

Infection status
  • The number of new cases has again hit a record high nationwide, and all prefectures have greatly exceeded the previous spread of infection as the spread of infection continues. The infection level in Okinawa continues to be higher than in other regions, while the use rate of beds is also severe. In addition, the rapid increase in cases of infection and close contacts nationwide is affecting not only medical institutions and welfare facilities, but also social activities as a whole.
  • The number of new infections nationwide by age group started to decrease among teenagers during the summer vacation, but it continues to increase in most age groups, including the elderly, who are at high risk of aggravation. In the past, increase in the number of severe cases and deaths has tended to lag behind a rapid increase in the number of new infections, and the numbers of severe cases and deaths have already started to increase, raising concerns about future trends.
  • Regarding the future infection status, according to the epi curve of onset dates and the short-term forecasts for large cities, some regions are thought to be passed the peak, and in some areas the number of new infections has actually decreased, although new infections are still rising in most regions. In addition, there are concerns about the increase in chances of contact due to summer vacation and the impact of people’s movements during Obon, and therefore it is necessary to pay attention with utmost caution, including the effects on the medical care provision system.
  • Factors in the continued increase in the number of infected individuals include (1) the gradual diminishing of the immunity acquired by the third vaccination and infection, (2) the increased contact that is expected due to the influence of summer vacation and Obon, etc., and (3) the presumed replacement of the Omicron variant by lineages such as BA.5.
  • Regarding the places of new infections, home is showing an increasing trend, with a decreasing trend at schools, due to the impact of summer vacation. In addition, the percentage of offices (workplaces) is increasing among people in their 20s to 60s (it must be kept in mind active epidemiological surveillance is focused on large cities, and that infection routes are not fully understood).
Factors that increase and suppress infection
  1. It is thought that infection status is affected by the following changes in factors that increase and suppress infection.

  1. [Vaccination]

    It has become clear that as a certain period elapses after the third vaccination, the infection prevention effect is attenuated compared to the aggravation prevention effect. In addition, the immunity acquired from previous infections is expected to similarly decline in the future.

  2. [Contact patterns]

    Although the nighttime population is overall flat, in metropolitan areas such as Tokyo, Kanagawa, Aichi, and Osaka, there are regions where the number is increasing, including the high-risk late night.

  3. [Epidemic strain]

    After the prevalence of BA.2 lineage, it is estimated that the BA.5 lineage will become mainstream and replace it. The BA.5 lineage is thought to increase the number of infected persons more easily, and there is concern about immune escape, which may be a factor in increasing the number of infected persons.

  4. [Climatic factors]

    It is a time when indoor activities increase due to rising temperatures, but ventilation may be difficult because air conditioning is prioritized.

Status of medical care provision system
  • Nationwide, the burden on the outpatient examination system is increasing, and the use rate of beds continues to increase almost nationwide, mostly exceeding 30% including in large cities, and the number of regions exceeding 50% is also increasing. In addition, the numbers of home care recipients and medical treatment adjustments are increasing in most regions, and are rapidly increasing in some regions.
  • Especially in Okinawa, the use rate of beds continues to rise, exceeding 70%, and the situation is severe, and nationwide, the increasing number of infections among healthcare workers is placing a burden on the medical care provision system. In the field of nursing care also, the difficult situation continues due to the increasing numbers of patients being treated in facilities and of infections among workers.
  • The positive rate of the test has increased, and there is concern whether the test is being appropriately received by those who need it, such as people with symptoms.
  • Regarding cases of difficult ambulance transport, both suspected non-COVID-19 cases and suspected COVID-19 cases continue to increase rapidly in many areas, and although the number of incidents has peaked in some areas, we cannot be optimistic about the cause, as a thorough analysis is needed. In addition, as hot weather continues, careful attention should be paid to the increase in ambulance transportation due to heat stroke.

Measures to be taken

Basic concepts
  • In the midst of rapid spread of infection, it is necessary to reduce as much as possible the chances of contacts which risk infection, based on the various knowledge that Japanese society has already learned. Also, in order to maintain socio-economic activities, it is necessary to work on methods for people to avoid infecting and being infected.
  • To this end, the national and local governments will remind the public of the need for routine infection control measures and take measures to support the public's efforts to prevent infection. In addition, efforts must be made to reduce the number of infected people so as not to increase the numbers of severe cases and deaths as much as possible, and further efforts should be made to strengthen the medical care provision system.
  1. 1. Further promotion of vaccination
    • Since the 4th vaccination has a limited effect in preventing infection, it has been promoted at facilities for the elderly with the aim of preventing aggravation. However, in light of the recent rapid spread of infection, the target has been expanded to include healthcare workers and those working in facilities for the elderly.
    • It is necessary to continue to promote the third vaccination by active publicity for the age groups and regions in which the vaccination rate is low.
  2. 2. Use of tests
    1. Based on the recommendations of the 17th meeting of the Novel Coronavirus Subcommittee, the national and local governments are required to secure a system that enables testing, and further utilize testing.

    2. [The Elderly]
      • Frequent tests (about 2 or 3 times a week for facility workers) are required for workers at facilities for the elderly.
      • Depending on the circumstances in the area, testing at appropriate occasions (e.g. Obon, when contact with relatives who have returned home is expected) is recommended for users of facilities for the elderly.
    3. [Children]
      • Depending on the circumstances in the area, if a cluster occurs it is necessary to carry out frequent testing of teachers and staff at nursery schools and kindergartens.
      • At the discretion of local governments and schools, it is necessary to thoroughly observe health, test those with some symptoms, and prevent outbreaks while allowing participation in club activities such as tournaments and school trips.
    4. [Young people]
      • Preliminary testing is further recommended when having a meal with a large number of people or when interacting with the elderly (especially when contacting them during the Obon/summer vacation homecoming).
      • A self-testing system for fever outpatients should be established, in which patients with symptoms can self-test using an antigen qualitative test kit, and if the result is positive, they can promptly undergo health observation.
      • In order to promote the above efforts, it is important for the government to provide a stable supply including distribution, by purchasing antigen qualitative test kits, distributing them to prefectural governments, and providing coordination support.
  3. 3. Effective ventilation
    • Based on the recommendations of the 17th meeting of the Novel Coronavirus Subcommittee, it is necessary to publicize and recommend effective ventilation methods in the summer when ventilation becomes insufficient due to the use of air conditioners (how to create airflow considering aerosols, installation of partitions that do not block airflow, etc.).
  4. 4. Securing a medical care provision system
    • In preparation for further spread of infection, prefectural governments must take measures to avoid overcrowding of beds and fever outpatient sections with the support of the national government.
    • Immediate responses such as securing beds by phase raising, and development of temporary medical facilities that play the role of supplementing hospital beds  
    • Appropriate coordination for patients who need inpatient treatment so that they can be hospitalized preferentially
    • Further strengthen medical support for testing and facilities for the elderly, based on an intensive implementation plan at facilities for the elderly
    • Securing and expanding logistical support hospitals, coordinating the transfer of patients who meet the criteria for release of medical care, and improving the hospital turnover rate by informing that the decision on early discharge should be 4 days as a rule
    • Promotion of flexible and efficient use of hospital beds through zoning for each hospital room
    • Establishment of a self-testing system for fever outpatients, in which patients with symptoms can self-test using an antigen qualitative test kit, and if the result is positive, they can promptly undergo health observation.
    • Strengthening of the supply system of the antigen qualitative test kits, and understanding and publicizing the cases of home care without going through a fever outpatient section
    • Establishing and strengthening a system that enables appropriate and early administration of therapeutic drugs
    • Response to the increasing trend of ambulance transport difficulties. In addition to confirming the acceptance system for patients other than COVID-19 patients, spreading awareness of heat stroke prevention and warning of increased emergency transportation due to heat stroke.
    • For those who are recuperating at home or staying overnight, in addition to calling for the use of consultations such as call centers, raise awareness of guidelines for visiting medical institutions and using ambulances
    • Ensuring that workplaces and schools do not require test certificates at the start of medical treatment
    • Further promote the reduction of burdens, such as hospitalization coordination and outsourcing/unification of operations by the hospitalization coordination division, so that public health center operations will not be strained.
  5. 5. Surveillance
    • It is necessary to promptly consider effective and appropriate surveillance, in order to properly grasp trends regarding occurrences. In addition, it is necessary to continue monitoring the trends of variants through genomic surveillance.
  6. 6. Re-inspection and implementation of basic infection control
    • Re-inspection and implementation of the following basic infection control measures are needed.
    • Continue proper wearing of nonwoven masks, hand hygiene, thorough ventilation, etc.
    • Avoid situations with a high risk of infection, such as the three Cs, congestion, or loud voices.
    • Eating and drinking should be done with as few people as possible, and masks should be worn except while eating and drinking.
    • People with symptoms such as sore throat, cough, and fever should refrain from going out.
    • Refer to guidelines for hospital visits and use of an ambulance.
    • In order to reduce the chances of contact, it is necessary to promote the use of telework again at the workplace.
    • Organizers of events, meetings, and such should fully evaluate the epidemic situation and risk of infection in the area, and consider whether or not to hold the meeting, and if it is held, measures should be taken to minimize the infection risk.
<< Reference: Findings on the characteristics of the Omicron variant and its sublineages >>
  1. [Infectivity/transmissibility]

    It has been confirmed that compared to the Delta variant, the generation time has shortened to approximately 2 days (approximately 5 days for Delta). The doubling time and incubation period have also shortened, the risk of re-infection and secondary infection after infection has increased, and the speed of infection spread is very fast. According to the reported data, pre-symptomatic transmission has probably occurred to some extent as with the previous strains.

  2. [Place/route of infection]

    In Japan, many cases of infection have occurred through the same opportunities as before (spending time indoors in locations with inadequate ventilation, eating and drinking, etc.), and infection is considered to have occurred via the same routes as before (droplets adhering to mucosa, aerosol inhalation, contact infection, etc.).

  3. [Severity]

    It has been suggested that infection with the Omicron variant presents a lower risk of hospitalization or aggravation than the Delta variant. However, analyses to date show that the fatality due to infection with the Omicron variant is higher than that due to seasonal influenza. It is also suggested that the incidence of pneumonia is higher than that of seasonal influenza, but given the limited data, it needs to be investigated by various analyses. The death toll from the previous outbreak compared to last summer's outbreak had a higher proportion of people aged 80 and over. It is reported that there are many cases in which the new coronavirus infection is not the direct cause of death, for example, people who have been in a facility for the elderly before the infection are infected and die due to the worsening of the underlying disease. Attention should also be paid to worsening of the condition of elderly infected people and infected people with an underlying disease, and to the onset of heart failure and aspiration pneumonia.

  4. [Duration of viral shedding]

    Viral shedding in individuals infected with the Omicron variant decreases over time. In patients with symptoms, it has been shown that the possibility of viral shedding is low from 10 days after the date of onset, and that no shedding is observed after 8 days from the date of diagnosis in those without symptoms.

  5. [Vaccine effect]

    For infection with the Omicron variant, the preventive effects of a first vaccination against infection and disease onset are markedly reduced. Its preventive effect on hospitalization is reported to be maintained at a certain level for the first 6 months, but subsequently decreases to 50% or less. On the other hand, it has been reported overseas that a third vaccination restores the infection-preventing effect, onset-preventing effect, and hospitalization-preventing effect against infection by the Omicron variant, as well as information regarding how these vaccine effects are attenuated after a third vaccination. Regarding the fourth vaccination, while the preventive effect against aggravation was not reduced for 6 weeks, the preventive effect against infection was limited, and it was reported that the effect lasted only for a short time.

  6. [Omicron variant sublineages]

    Worldwide, the proportion of the BA.5 lineage is increasing, suggesting that this lineage is superior to the BA.2 lineage in terms of increasing the number of infected people. The number of positive tests is on the rise globally, as replacement by the BA.5 lineage proceeds. The BA.5 lineage has shown a tendency to escape existing immunity compared with the BA.1 and BA.2 lineages, but no clear findings on the infectivity have been shown. The effective reproduction number of the BA.5 lineage calculated based on the data of Tokyo was about 1.27 times that of BA.2. It was also estimated that it was about 1.3 times higher in samples collected from private testing institutions nationwide.

    According to the WHO report, the findings accumulated from multiple countries indicate that there is no increase in the severity of the BA.5 lineage compared to existing Omicron variants. On the other hand, the pathogenicity of the BA.5 lineage is reportedly higher than that of the BA.1 and BA.2 lineages, based on Japanese laboratory data, but it has not been confirmed clinically at this time. Although it is unknown whether it is due to the traits of the BA.5 lineage, it should be noted that the numbers of inpatient cases and severe cases are increasing in countries where the number of infected people is increasing mainly in the BA.5 lineage. According to genomic surveillance in Japan, the detection rate of the BA.5 lineage is increasing, and replacement has presumably progressed.

    In addition, the BA.2.75 lineage, which has been reported mainly in India since June, has been detected in Japan, but no clear findings have been obtained overseas regarding its infectivity and severity compared with other lineages. It is necessary to continue to collect and analyze the situation and findings in other countries regarding these characteristics of the virus, and to continue monitoring by genome surveillance.

Figures (Number of new infections reported etc.) (PDF)

 

92nd Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (July 27, 2022). Material 1

 

Evaluation of the latest infection status, etc.

Infection status

  • Nationwide, the number of new cases of infection (by date of report) was about 978 per 100,000 in the last week, continuing to rapidly increase at a ratio of this week to last week of 1.89 (although the effect of 3 consecutive holidays must be considered when comparing to the previous week).
    It is again the highest level of infection ever in Japan, increasing in all age groups.
  • As the number of new cases of infection increases, the number of patients receiving medical treatment continues to increase, and although the use rate of beds shows regional differences, and in some regions, there is a heavy burden on the medical care provision system.
    In addition, the numbers of severe cases and deaths continue to increase, and attention should be paid to future trends.

    Effective reproduction number: On a national basis, the most recent number is greater than 1 (1.24, as of July 10), while the figure stands at 1.26 in both the Tokyo metropolitan and Kansai areas.

Local trends

* The value for new cases of infection is the number of persons per 100,000 among the total number for the latest week, based on reporting dates.

  1. Hokkaido

    The number of new cases of infection was approximately 494 (about 569 in Sapporo City), with a ratio to the previous week of 2.29. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 20%.

  2. North Kanto

    In Ibaraki, Tochigi, and Gunma, the numbers of new cases of infection were about 530, 682, and 692, with ratios to the previous week of 2.08, 2.57, and 2.10, respectively. In Ibaraki, Tochigi, and Gunma, they were mainly in their 30s or younger. The use rates of beds are slightly less than 50% in Ibaraki, approximately 40% in Tochigi, and approximately 50% in Gunma.

  3. Tokyo metropolitan area (Tokyo and 3 neighboring prefectures)

    The number of new cases of infection in Tokyo was approximately 1,438, with a ratio to the previous week of 1.79. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 40%, while the use rate of beds for severe cases is slightly more than 50%. In Saitama, Chiba, and Kanagawa, the numbers of new cases of infection were about 927, 892, and 875, with ratios to the previous week of 1.78, 1.85, and 1.50, respectively. The use rates of beds are approximately 50% in Saitama, slightly more than 50% in Chiba and slightly less than 70% in Kanagawa.

  4. Chukyo/Tokai

    The number of new cases of infection in Aichi was approximately 1,130, with a ratio to the previous week of 2.17. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 40%. In Gifu, Shizuoka, and Mie, the numbers of new cases of infection were about 758, 885, and 730, with ratios to the previous week of 2.16, 2.19, and 1.83, respectively. The use rates of beds are slightly more than 30% in Gifu, approximately 70% in Shizuoka, and slightly more than 40% in Mie.

  5. Kansai area

    The number of new cases of infection in Osaka was approximately 1,555, with a ratio to the previous week of 2.18. The infected individuals are mainly in their 30s or younger. The use rate of beds is approximately 50%, while the use rate of beds for severe cases is slightly less than 30%. In Shiga, Kyoto, Hyogo, Nara, and Wakayama, the numbers of new cases of infection were about 717, 1,035, 1,060, 826, and 771, with ratios to the previous week of 1.57, 1.92, 1.91, 1.49, and 1.73, respectively. The use rates of beds are slightly more than 50% in Shiga and Hyogo, slightly more than 30% in Kyoto, slightly more than 40% in Nara, and slightly more than 60% in Wakayama.

  6. Kyushu

    The number of new cases of infection in Fukuoka was approximately 1,481, with a ratio to the previous week of 2.01. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 60%. In Saga, Nagasaki, Kumamoto, Oita, Miyazaki, and Kagoshima, the numbers of new cases of infection were about 1,231, 834, 1,461, 1,055, 1,097, and 1,133, with ratios to the previous week of 1.58, 2.01, 1.63, 1.73, 1.78, and 1.70, respectively. The use rates of beds are slightly more than 40% in Saga, slightly more than 50% in Nagasaki, approximately 60% in Kumamoto, slightly more than 40% in Oita, slightly less than 40% in Miyazaki, and slightly more than 60% in Kagoshima.

  7. Okinawa

    The number of new cases of infection was the highest nationwide at approximately 2,260, with a ratio of this week to last week of 1.46. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 80%, while the use rate of beds for severe cases is slightly more than 30%.

  8. Areas other than the above

    Miyagi, Akita, Tochigi, Niigata, Toyama, Yamanashi, Shimane, and Kagawa had ratios to the previous week of 2.85, 2.67, 2.57, 2.35, 2.61, 2.38, 1.18, and 2.11, respectively. The number of new cases of infection was approximately 969 in Shimane. The use rates of beds are approximately 60% in Aomori, approximately 50% in Fukushima and Hiroshima, and slightly more than 50% in Ishikawa.

Future outlook and measures to be taken

  • Infection status
    • The number of new cases has again hit a record high nationwide, and all prefectures have greatly exceeded the previous spread of infection as the rapid spread of infection continues. The infection level in Okinawa continues to be higher than in other regions, and the highest so far, while the use rate of beds is also severe. In addition, the rapid increase in cases of infection and close contact are having an impact on social activities overall.

    • The number of new cases of infection by age group is increasing nationwide in all age groups, including the elderly. In the past, increase in the number of severe cases and deaths has tended to lag behind a rapid increase in the number of new infections, and there are concerns about these increases as the number of infected elderly people increases.

    • Regarding the future infection situation, the epi curve of the onset date and short-term forecasts in large cities predict that the number of new infections will continue to increase or at best level off in many regions and will reach record highs nationwide. Close attention should be paid to the medical care provision system, with the utmost caution.

    • Factors in the continued increase in the number of infected individuals include (1) the gradual diminishing of the immunity acquired by the third vaccination and infection, (2) the increased contact that is expected due to the influence of summer vacation etc., and (3) the presumed replacement of the Omicron variant by lineages such as BA.5.

    • Regarding the places of infection of new cases, there is an increasing trend at home and a decreasing trend at schools (it must be kept in mind active epidemiological surveillance is focused on large cities, and that infection routes are not fully understood).

  • Factors that increase and suppress infection
    1. It is thought that infection status is affected by the following changes in factors that increase and suppress infection.

    1. [Vaccination]

      It has become clear that as a certain period elapses after the third vaccination, the infection prevention effect is attenuated compared to the aggravation prevention effect. In addition, the immunity acquired from previous infections is expected to similarly decline in the future.

    2. [Contact patterns]

      The nighttime population is decreasing in many regions, including large cities such as Tokyo, Aichi, and Osaka. However, in some areas the number of infections has leveled off or turned to increase.

    3. [Epidemic strain]

      After the prevalence of BA.2 lineage, it is estimated that the BA.5 lineage will become mainstream and replace it. In particular, the BA.5 lineage is thought to increase the number of infected persons more easily, and there is concern about immune escape, which may be a factor in increasing the number of infected persons.

    4. [Climatic factors]

      It is a time when indoor activities increase due to rising temperatures, but ventilation may be difficult because air conditioning is prioritized.

  • Medical care provision system
    • Nationwide, the burden on the outpatient examination system is increasing, and although there are regional differences in the use rate of beds, it has risen to 30% in most regions, including large cities, due to the increase in the number of new infections, and the number of regions exceeding 50% is also increasing. In addition, the numbers of home care recipients and medical treatment adjustments are increasing in most regions and are rapidly increasing in some regions.

    • Especially in Okinawa, the use rate of beds continues to rise, exceeding 80%, and the situation is severe, and nationwide, the increasing number of infections among healthcare workers is placing a burden on the medical care provision system. In the field of nursing care also, the difficult situation continues due to the increasing numbers of patients being treated in facilities and of infections among workers.

    • The positive rate of the test has increased, and there is concern whether the test is being appropriately received by those who need it, such as people with symptoms.

    • Cases of difficult emergency transportation continue to increase rapidly nationwide for both suspected non-COVID-19 cases and suspected COVID-19 cases, although there are regional differences. In addition, careful attention should be paid to the increase in ambulance transportation due to heat stroke.

  • Measures and basic concepts
    • In the midst of rapid spread of infection, it is necessary to reduce as much as possible the chances of contacts which risk infection, based on the various knowledge that Japanese society has already learned. Also, in order to maintain socio-economic activities, it is necessary to work on methods for people to avoid infecting and being infected.

    • To this end, the national and local governments will remind the public of the need for routine infection control measures and take measures to support the public's efforts to prevent infection. It is also necessary to make further efforts to strengthen the medical care provision system.

    1. 1. Further promotion of vaccination
      • Since the 4th vaccination has a limited effect in preventing infection, it has been promoted at facilities for the elderly with the aim of preventing aggravation. However, in light of the recent rapid spread of infection, the target has been expanded to include healthcare workers and those working in facilities for the elderly.
      • It is necessary to continue to promote the third vaccination for the age groups and regions in which the vaccination rate is low.
    2. 2. Use of tests
      1. Based on the recommendations of the 17th meeting of the Novel Coronavirus Subcommittee, the national and local governments are required to secure a system that enables testing, and further utilize testing.

      2. [The Elderly]
        • Frequent tests (about 2 or 3 times a week for facility workers) are required for workers at facilities for the elderly.
        • Depending on the circumstances in the area, testing at appropriate occasions (e.g. Obon, when contact with relatives who have returned home is expected) is recommended for users of facilities for the elderly.
      3. [Children]
        • Depending on the circumstances in the area, if a cluster occurs it is necessary to carry out frequent testing of teachers and staff at nursery schools and kindergartens.
        • At the discretion of local governments and schools, it is necessary to thoroughly observe health, test those with some symptoms, and prevent outbreaks while allowing participation in club activities such as tournaments and school trips.
      4. [Young people]
        • Preliminary testing is further recommended when having a meal with a large number of people or when interacting with the elderly (especially when contacting them during the Obon/summer vacation homecoming).
        • It is necessary to establish a system for symptomatic patients to test themselves with a qualitative antigen test kit before visiting a medical institution. A stable supply, including distribution, is important so that those who need them can secure antigen qualitative test kits.
    3. 3. Effective ventilation
      • Based on the recommendations of the 17th meeting of the Novel Coronavirus Subcommittee, it is necessary to publicize and recommend effective ventilation methods in the summer when ventilation becomes insufficient due to the use of air conditioners (how to create airflow considering aerosols, installation of partitions that do not block airflow, etc.).
    4. 4. Securing a medical care provision system
      • Prefectural governments need to inspect and strengthen the following systems with the support of the national government, in preparation for further spread of infection.
      • Establishing and utilizing a call center, strengthening a system that enables prompt and smooth testing and safe home care
      • Building and strengthening a system that enables appropriate and early administration of therapeutic drugs.
      • Systematic preparation for further securing of hospital beds.
      • Promotion of flexible and efficient use of hospital beds through zoning for each hospital room.
      • Response to the increasing trend of ambulance transport difficulties. In addition to confirming the acceptance system for patients other than COVID-19 patients, spreading awareness of heat stroke prevention and warning of increased emergency transportation due to heat stroke. In addition, those who are at being treated home or staying overnight should be encouraged to use the consultation service. Furthermore, those who wish to visit a medical facility should be informed of the symptoms required for requesting an ambulance.
      • Further strengthen medical support for testing and facilities for the elderly, based on an intensive implementation plan at facilities for the elderly.
      • Further promote the reduction of burdens, such as hospitalization coordination and outsourcing/unification of operations by the hospitalization coordination division, so that public health center operations will not be strained.
    5. 5. Re-inspection and implementation of basic infection control
      • Continue proper wearing of nonwoven masks, hand hygiene, ventilation, etc. Avoid situations with a high risk of infection, such as the three Cs, congestion, or loud voices. Eating and drinking should be done with as few people as possible, and masks should be worn except while eating and drinking. People with symptoms such as sore throat, cough, and fever should refrain from going out. In order to reduce the chances of contact, it is necessary to re-inspect and thoroughly enforce basic infection countermeasures, such as promoting the use of telework again at the workplace. In addition, organizers of events, meetings, and such should fully evaluate the epidemic situation and risk of infection in the area, and consider whether or not to hold the meeting, and if it is held, measures should be taken to minimize the infection risk.
<< Reference: Findings on the characteristics of the Omicron variant and its sublineages >>
  1. [Infectivity/transmissibility]

    It has been confirmed that compared to the Delta variant, the generation time has shortened to approximately 2 days (approximately 5 days for Delta). The doubling time and incubation period have also shortened, the risk of re-infection and secondary infection after infection has increased, and the speed of infection spread is very fast. According to the reported data, pre-symptomatic transmission has probably occurred to some extent as with the previous strains.

  2. [Place/route of infection]

    In Japan, many cases of infection have occurred through the same opportunities as before (spending time indoors in locations with inadequate ventilation, eating and drinking, etc.), and infection is considered to have occurred via the same routes as before (droplets adhering to mucosa, aerosol inhalation, contact infection, etc.).

  3. [Severity]

    It has been suggested that infection with the Omicron variant presents a lower risk of hospitalization or aggravation than the Delta variant. However, analyses to date show that the fatality due to infection with the Omicron variant is higher than that due to seasonal influenza. It is also suggested that the incidence of pneumonia is higher than that of seasonal influenza, but given the limited data, it needs to be investigated by various analyses. The death toll from the previous outbreak compared to last summer's outbreak had a higher proportion of people aged 80 and over. It is reported that there are many cases in which the new coronavirus infection is not the direct cause of death, for example, people who have been in a facility for the elderly before the infection are infected and die due to the worsening of the underlying disease. Attention should also be paid to worsening of the condition of elderly infected people and infected people with an underlying disease, and to the onset of heart failure and aspiration pneumonia.

  4. [Duration of viral shedding]

    Viral shedding in individuals infected with the Omicron variant decreases over time. In patients with symptoms, it has been shown that the possibility of viral shedding is low from 10 days after the date of onset. In patients with no symptoms, it has been shown that viral shedding does not occur from 8 days after the date of diagnosis.

  5. [Vaccine effect]

    For infection with the Omicron variant, the preventive effects of a first vaccination against infection and disease onset are markedly reduced. Its preventive effect on hospitalization is reported to be maintained at a certain level for the first 6 months, but subsequently decreases to 50% or less. On the other hand, it has been reported overseas that a third vaccination restores the infection-preventing effect, onset-preventing effect, and hospitalization-preventing effect against infection by the Omicron variant, as well as information regarding how these vaccine effects are attenuated after a third vaccination. Regarding the fourth vaccination, while the preventive effect against aggravation was not reduced for 6 weeks, the preventive effect against infection was limited, and it was reported that the effect lasted only for a short time.

  6. [Omicron variant sublineages]

    Worldwide, the proportion of the BA.5 lineage is increasing, suggesting that this lineage is superior to the BA.2 lineage in terms of increasing the number of infected people. The number of positive tests is on the rise globally, as replacement by the BA.5 lineage proceeds. The BA.5 lineage has shown a tendency to escape existing immunity compared with the BA.1 and BA.2 lineages, but no clear findings on the infectivity have been shown. The effective reproduction number of the BA.5 lineage calculated based on the data of Tokyo was about 1.27 times that of BA.2. It was also estimated that it was about 1.3 times higher in samples collected from private testing institutions nationwide.

    According to the WHO report, the findings accumulated from multiple countries indicate that there is no increase in the severity of the BA.5 lineage compared to existing Omicron variants. On the other hand, the pathogenicity of the BA.5 lineage is reportedly higher than that of the BA.1 and BA.2 lineages, based on Japanese laboratory data, but it has not been confirmed clinically at this time. Although it is unknown whether it is due to the traits of the BA.5 lineage, it should be noted that the numbers of inpatient cases and severe cases are increasing in countries where the number of infected people is increasing mainly in the BA.5 lineage.

    The BA.5 lineage has been detected both in Japan and in quarantine. According to genomic surveillance, the detection rate of the BA.5 lineage is increasing, and replacement has presumably progressed. It is necessary to continue to collect and analyze the situation and findings in other countries regarding the characteristics of the virus, and to continue monitoring by genome surveillance.

Figures (Number of new infections reported etc.) (PDF)

 

90th Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (July 13, 2022). Material 1

 

Evaluation of the latest infection status, etc.

Infection status

  • The number of new cases of infection nationwide (by date of report) was about 290 per 100,000 in the last week, rapidly increasing at a ratio of this week to last week of 2.14.
    It is increasing in all prefectures and age groups.
  • As the number of new cases of infection increases, the number of patients receiving medical treatment is increasing, and although the use rate of beds is generally low, it is on the rise.
  • At present, the numbers of severe cases and deaths remain low.

    Effective reproduction number: On a national basis, the most recent number is above 1 (1.14 as of June 26), while the figure stands at 1.19 in the Tokyo metropolitan area and 1.16 in the Kansai area.

Local trends

* The value for new cases of infection is the number of persons per 100,000 among the total number for the latest week, based on reporting dates.

  1. Hokkaido

    The number of new cases of infection was approximately 111 (about 135 in Sapporo City), with a ratio to the previous week of 1.37. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 10%.

  2. North Kanto

    In Ibaraki, Tochigi, and Gunma, the numbers of new cases of infection were about 118, 122, and 160, with ratios to the previous week of 2.05, 2.58, and 2.70, respectively. In Ibaraki and Tochigi, they were mainly in their 30s or younger, and in Gunma, mainly in their 20s or younger. The use rates of beds are slightly more than 10% in Ibaraki and Gunma, and approximately 10% in Tochigi.

  3. Tokyo metropolitan area (Tokyo and 3 neighboring prefectures)

    The number of new cases of infection in Tokyo was approximately 446, with a ratio to the previous week of 2.37. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 20%, and the use rate of beds for severe cases is slightly more than 30%. In Saitama, Chiba, and Kanagawa, the numbers of new cases of infection were about 232, 246, and 296, with ratios to the previous week of 2.19, 2.33, and 2.41, respectively. The use rates of beds are slightly more than 20% in Saitama, Chiba, and Kanagawa.

  4. Chukyo/Tokai

    The number of new cases of infection in Aichi was approximately 294, with a ratio to the previous week of 2.26. The individuals are mainly in their 20s or younger. The use rate of beds is slightly less than 20%. In Gifu, Shizuoka, and Mie, the numbers of new cases of infection were about 235, 212, and 224, with ratios to the previous week of 2.18, 2.65, and 2.07, respectively. The use rates of beds are slightly less than 20% in Gifu and Shizuoka, and approximately 30% in Mie.

  5. Kansai area

    The number of new cases of infection in Osaka was approximately 421, with a ratio to the previous week of 2.22. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 20%, and the use rate of beds for severe cases is slightly less than 10%. In Shiga, Kyoto, Hyogo, Nara, and Wakayama, the numbers of new cases of infection were about 243, 284, 276, 250, and 306, with ratios to the previous week of 2.29, 2.27, 2.13, 3.01, and 2.09, respectively. The use rates of beds are approximately 20% in Kyoto, slightly more than 40% in Wakayama and Shiga, slightly less than 30% in Hyogo, and slightly more than 10% in Nara.

  6. Kyushu

    The number of new cases of infection in Fukuoka was approximately 406, with a ratio to the previous week of 2.27. The individuals are mainly in their 20s or younger. The use rate of beds is slightly more than 20%. In Saga, Nagasaki, Kumamoto, Oita, Miyazaki, and Kagoshima, the numbers of new cases of infection were about 626, 298, 640, 402, 379, and 409, with ratios to the previous week of 2.00, 1.58, 1.75, 2.24, 2.24, and 1.97, respectively. The use rates of beds are approximately 30% in Saga, slightly more than 20% in Nagasaki, slightly less than 50% in Kumamoto, approximately 30% in Oita, slightly more than 30% in Kagoshima, and approximately 20% in Miyazaki.

  7. Okinawa

    The number of new cases of infection was the highest nationwide at approximately 1,118, with a ratio of this week to last week of 1.52. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 50%, while the use rate of beds for severe cases is slightly more than 20%.

  8. Area other than the above

    In Iwate, Akita, Yamanashi, Nagano, Tottori, and Shimane, the ratio to the previous week was 2.77, 3.57, 2.61, 2.58, 2.18, and 1.80, respectively, and the number of new cases of infection in Shimane was about 776. The use rates of beds are slightly less than 30% in Aomori, slightly more than 20% in Fukushima, and slightly more than 30% in Shimane.

Future outlook and measures to be taken

  • Infection status
    • The number of new cases of infection is increasing in all prefectures, and in many areas the increase is large and the infection is spreading rapidly. In addition, Okinawa continues to have a higher level of infection than other areas, and is now the highest level to date.

    • The number of new cases of infection by age group increased in all age groups, and the rate of increase was particularly large among those in their 50s or younger.

    • Regarding the places of infection of new cases, the proportion at schools and at home are increasing (it must be kept in mind active epidemiological surveys are focused on large cities, and that infection routes are not fully understood). In Tokyo, an increase in infections at places of eating, drinking, and work has also been reported.

    • Regarding future infection status, the number of new infections is expected to continue to increase in many regions, based on the epi-curve of the date of onset and short-term forecast in large cities. Since (1) the immunity acquired by the third vaccination and infection is gradually decreasing, (2) an increase in contact is expected due to the influence of three consecutive holidays and summer vacation, and (3) replacement of the Omicron variant by lineages such as BA.5 is proceeding, there is concern that the number of infects will continue to increase rapidly, and it will be necessary to pay close attention to the impact on the medical care provision system.

  • Factors that increase and suppress infection
    1. It is thought that infection status is affected by the following changes in factors that increase and suppress infection.

    1. [Vaccination]

      The third vaccination is proceeding, but it should be noted that as a certain period elapses after the third vaccination, it is expected that the infection prevention effect will be weakened compared to the aggravation prevention effect. In addition, the immunity acquired from previous infections is expected to similarly decline in the future.

    2. [Contact patterns]

      Although the nighttime population is decreasing in some regions, it shows an increasing trend in many areas, mainly in large cites. Since in some areas the number approaches or exceeds the peak at the end of last year, it is necessary to pay attention to the impact on the infection status.

    3. [Epidemic strain]

      After the prevalence of BA.2 lineage, the replacement by BA.5 lineage is progressing. In particular, the BA.5 lineage is thought to increase the number of infected persons more easily, and there is concern about immune escape, which may be a factor in increasing the number of infected persons.

    4. [Climatic factors]

      It is a time when indoor activities increase due to rising temperatures, but ventilation may be difficult because air conditioning is prioritized.

  • Medical care provision system
    • Nationwide, the use rate of beds is generally low, but as the number of newly infected individuals increases, it has been on an upward trend in some areas, including large cities. Especially in Okinawa, the use rate of beds tends to be higher than in the country as a whole.

    • In cases of difficult emergency transportation, there is an increasing trend nationwide for both suspected non-COVID-19 cases and suspected COVID-19 cases. In addition, careful attention should be paid to the increase in ambulance transportation due to heat stroke.

  • Efforts based on the spread of infection with the Omicron variant
    1. [Surveillance, etc.]

      It is necessary to consider effective and appropriate surveillance, in order to properly grasp trends regarding occurrences. In addition, it is necessary to continue monitoring the trends of variants through genomic surveillance. For severe cases, clusters, and other applicable cases, confirmation via PCR testing for mutant strains and a whole-genome analysis is required.

    2. [Efforts by local governments]
      1. The number of new cases of infection is increasing in all prefectures, and local governments need to continue to inspect and strengthen their testing, health, and medical care provision systems.

      • It is necessary to strengthen the system to enable prompt and smooth testing and safe home care that keeps up with the spread of infections in the region, and continue the inspection and strengthening of testing, health, and medical care provision systems that have been developed so far, such as further securing of beds.
      • Recently, effective and less burdensome measures against infection in medical and nursing care settings have been newly seen, and while knowledge about the risk of infection and infection control has accumulated, it is important to consider reasonable measures against infection according to the actual conditions at each facility.
      • When strengthening and thoroughly implementing a medical care support system for the elderly, it is important for medical and nursing care departments to cooperate, and proceed in consultation with local concerned parties so that the system that has been developed thus far is functioning properly.
      • Based on administrative notices such as to prioritize health observation and improve efficiency in processing notices of the occurrence of patients, in order to efficiently carry out public health center operations and maintain the public health center functions required in the region, it is important to secure a system for outsourcing or centralization at the main office.
    3. [Provision of information to unvaccinated individuals, and those receiving the third or fourth vaccination, etc.]
      • It is important for local governments to promote the provision of information on vaccination. The third and fourth vaccinations must also be steadily implemented, along with vaccinations for unvaccinated persons. The main purpose of the third vaccination is prevention of onset and aggravation. As of July 12, the rate of third vaccinations was about 90% for the elderly aged 65 years and older, and about 62% overall. It is necessary to steadily implement a third vaccination in subjects, and to vaccinate as many desiring recipients as possible. A fourth vaccination was started to prevent aggravation in persons aged 60 years and older, persons with underlying diseases at high risk of severe symptoms, and other persons deemed by doctors to be at a high risk of severe symptoms. It also became possible to start administration of a new vaccine for the first to third doses. This vaccine is different from the previous new coronavirus vaccine and can ensure a diversity of vaccines. It is also manufactured in Japan, ensuring the stability of vaccine supply.
      • Vaccination of children from 5 to 11 years old is being implemented as a special temporary vaccination, and it is necessary to promote vaccination, considering that the obligation to make efforts does not apply to these children. In hope of preventing infections in children, it is also important for parents and the adults around them to be vaccinated a third time.
    4. [Quarantine measures]

      It is necessary to verify the step-by-step review of quarantine measures, while taking into account the status of the current epidemic situation overseas and in Japan. In addition, while continuing pre-departure tests and responding to the risk of inflow, whole genome analysis should be continued for those who are positive in the immigration test to monitor strains circulating overseas.

  • Strengthening and thorough implementation of infection prevention measures based on the characteristics of the Omicron variant
    1. In situations and places where infection is widespread, it is necessary to strengthen and thoroughly implement infection control measures, based on the characteristics of the Omicron variant.

    2. [Schools, kindergartens, nursery schools, etc.]

      Infection control measures including active promotion of vaccinations for teachers and nursery teachers will be thoroughly implemented, as well as infection control measures for children, while sharing situations where the risk of infection in children and students increases with staff, children, parents, etc. It is also necessary to continue educational activities and social functions as far as possible. It is important to establish an environment where children and workers can take a leave of absence, in the case of any poor health conditions. At the same time, thorough infection control measures are also required at home. Masks are not recommended for children under 2 years of age, and for preschool children over 2 years of age, there are concerns about the risk of heat stroke and the effects of difficulty in seeing facial expressions. Therefore, it is necessary to thoroughly inform nursery schools, etc. that masks are not uniformly required, and that children should not be forced to wear them. Schools must be thoroughly informed that it is not necessary to wear a mask during physical education classes, athletic club activities, or when going to and from school.

    3. [Facilities for the elderly, etc.]

      Thorough measures are needed to control infections in the elderly. Therefore, workers are actively examined. In order to prevent aggravation, the fourth vaccination of residents will proceed. Further, it is important to secure external support systems for infection control and medical care at facilities, and to promptly intervene when infection is confirmed at facilities.

    4. [Workplace, etc.]

      In order to maintain social functions, in addition to reinspection and utilization of business continuity plans, efforts are required to utilize telework and promote the taking of time off. In addition, thorough health management of employees, including the use of apps, and securing an environment where they can take a leave of absence if they are even a little unwell are necessary. In addition, a third vaccination in the workplace should be actively promoted.

  • It is essential to widely share the current infection status with citizens and business operators, and cooperate toward preventing the spread of the infection.
    1. The number of new cases of infections is increasing in all prefectures. The number of contacts is expected to increase due to the three consecutive holidays and summer vacation. For this reason, in order to minimize the increase in the number of cases of infection, it is necessary to thoroughly implement basic infection control measures and daily health management, and cooperate in efforts to reduce the risk of infection.

    2. [Vaccination]

      In preparation for the spread of infection, a fourth vaccination is recommended for the elderly and those at risk of severe illness. It is important for people to receive the third vaccination, regardless of type. People with the novel coronavirus disease may experience severe conditions even if they are young, and may also suffer from prolonged symptoms. Accordingly, it is necessary to promote vaccinations not only in the elderly, but also in younger persons, in order to protect their health. It is important to consider vaccination again for people who have not received the first or second vaccination.

    3. [Thorough infection control]

      As basic infection control measures, it is necessary to continue to ensure the proper wearing of nonwoven masks, hand washing, ventilation, etc. The risk of infection becomes highest when the three Cs (crowded places, closed spaces, and close contact) overlap. However, even a single C should be avoided as much as possible.

    4. [When going out]

      Crowded or poorly ventilated places with a large number of people and loud voices, where the risk of infection is high, should be avoided. Activities with other persons should be carried out in a small group of people who usually meet each other. Eating and drinking together should be done in a small group without speaking to the extent possible, and masks should be worn at all times except while eating and drinking. On the other hand, the use of a mask is not necessary outdoors, except when talking at a close distance. Especially in summer, removing the mask outdoors is recommended from the viewpoint of preventing heat stroke.

    5. [Health management]

      It is necessary to refrain from going out if you feel a little unwell, such as a mild fever or fatigue, and to consult with a physician and undergo tests according to local government policy. Particularly, if there is a chance of meeting people at high risk of severe illness, such as the elderly, it is necessary to check the condition before visiting, and also to recommend a preliminary test using an antigen test kit, etc.

<< Reference: Findings on the characteristics of the Omicron variant and its sublineages >>
  1. [Infectivity/transmissibility]

    It has been confirmed that compared to the Delta variant, the generation time has shortened to approximately 2 days (approximately 5 days for Delta). The doubling time and incubation period have also shortened, the risk of re-infection and secondary infection after infection has increased, and the speed of infection spread is very fast. According to the reported data, pre-symptomatic transmission has probably occurred to some extent as with the previous strains.

  2. [Place/route of infection]

    In Japan, many cases of infection have occurred through the same opportunities as before (spending time indoors in locations with inadequate ventilation, eating and drinking, etc.), and infection is considered to have occurred via the same routes as before (droplets adhering to mucosa, aerosol inhalation, contact infection, etc.).

  3. [Severity]

    It has been suggested that infection with the Omicron variant presents a lower risk of hospitalization or aggravation than the Delta variant. However, analyses to date show that the fatality due to infection with the Omicron variant is higher than that due to seasonal influenza. It is also suggested that the incidence of pneumonia is higher than that of seasonal influenza, but given the limited data, it needs to be investigated by various analyses. People aged 80 years and older account for a larger proportion of deaths in this wave of the spread of the infection than during last summer. It has been reported that there are many cases in which the new coronavirus infection is not the direct cause of death, for example, people who have been in a facility for the elderly before the infection are infected and die due to the worsening of the underlying disease. Attention should also be paid to worsening of the condition of elderly infected people and infected people with an underlying disease, and to the onset of heart failure and aspiration pneumonia.

  4. [Duration of viral shedding]

    Viral shedding in individuals infected with the Omicron variant decreases over time. In patients with symptoms, it has been shown that the possibility of viral shedding is low at 10 days after the date of onset. In patients with no symptoms, it has been shown that viral shedding does not occur 8 days after the date of diagnosis.

  5. [Vaccine effect]

    For infection with the Omicron variant, the preventive effects of a first vaccination against infection and disease onset are markedly reduced. Its preventive effect on hospitalization is reported to be maintained at a certain level for the first 6 months, but subsequently decreases to 50% or less. On the other hand, it has been reported overseas that a third vaccination restores the infection-preventing effect, onset-preventing effect, and hospitalization-preventing effect against infection by the Omicron variant, as well as information regarding how these vaccine effects are attenuated after a third vaccination.

  6. [Sublineages of the Omicron Variant]

    Worldwide, the proportions of the BA.4 and BA.5 lineage are increasing, suggesting that these lineages are superior to the BA.2 lineage in terms of increasing the number of infected people. The number of positive tests is on the rise globally, as replacement by the BA.4 and BA.5 lineages proceeds. The effective reproduction number of the BA.5 lineage calculated based on the data of Tokyo was about 1.27 times that of BA.2.

    According to the WHO report, the findings accumulated from multiple countries indicate that there is no increase in the severity of the BA.4 and BA.5 lineages compared to existing Omicron variants. On the other hand, the pathogenicity of the BA.5 lineage is reportedly higher than that of the BA.1 and BA.2 lineages, based on Japanese laboratory data, but it has not been confirmed clinically at this time. It should be noted that the numbers of inpatient cases and severe cases are increasing in countries where the number of infected people is increasing mainly in BA.4 and BA.5 lineages.

    The BA.4 lineage and BA.5 lineage have both been detected in Japan and in quarantine. According to genomic surveillance, the BA.2 lineage continues to be the mainstream in Japan, but the detection rate of the BA.5 lineage is increasing, and replacement is progressing. It is necessary to continue to collect and analyze the situation and findings in other countries regarding the characteristics of the virus, and to continue monitoring by genome surveillance.

Figures (Number of new infections reported etc.) (PDF)

 

89th Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (June 30, 2022). Material 1

 

Evaluation of the latest infection status, etc.

Infection status

  • The number of new cases of infection nationwide (by date of report) was about 92 per 100,000 in the last week, increasing to a ratio of this week to last week of 1.17. The number of new cases of infection by age group slightly increased in almost all age groups.
  • With the number of new cases of infection increasing, the number of patients being treated and number of severe cases have gradually increased. The use rate of beds is generally low, and the number of deaths is on a decreasing trend.

    Effective reproduction number: On a national basis, the most recent number is below 1, at 0.98 (as of June 12). The figure stands at 1.02 in the Tokyo metropolitan area and 0.97 in the Kansai area.

Local trends

* The value for new cases of infection is the number of persons per 100,000 among the total number for the latest week, based on reporting dates.

  1. Hokkaido

    The number of new cases of infection is approximately 77 (roughly 85 in Sapporo City), with a ratio of numbers for this week to last week of less than 1 (0.85). The infected individuals are mainly in their 30s or younger. The number leveled off in those in their 70s, and decreased slightly or decreased in other age groups. The use rate of beds is slightly less than 10%.

  2. North Kanto

    In Ibaraki, the number of new cases of infection is approximately 52, with a ratio of this week to last week of more than 1 (1.01). The individuals are mainly in their 20s or younger. The number slightly increased in those in their teens and 20s, slightly increased in the 40s and 50s, and decreased slightly or decreased in other age groups. The use rate of beds is slightly less than 10%. In Tochigi and Gunma, the numbers of new cases of infection are approximately 30 and 34, respectively, with a ratio of this week to last week of less than 1 (0.85 and 0.72). The use rates of beds are slightly less than 10% in Gunma and less than 10% in Tochigi.

  3. Tokyo metropolitan area (Tokyo and 3 neighboring prefectures)

    In Tokyo, the number of new cases of infection is approximately 118, with a ratio to the previous week of more than 1 (1.37). The infected individuals are mainly in their 30s or younger. It has increased or slightly increased in all age groups. The use rate of beds is slightly more than 10%, and the use rate of beds for severe patients is slightly more than 10%. In Saitama, Chiba, and Kanagawa, the numbers of new cases of infection are approximately 65, 63, and 77, respectively, with a ratio of this week to last week of more than 1 (1.13, 1.27, and 1.25). The use rate of beds is approximately 10% in Saitama, and slightly less than 10% in Chiba and Kanagawa.

  4. Chukyo/Tokai

    In Aichi, the number of new cases of infection is approximately 88, with a ratio of this week to last week of more than 1 (1.21). The individuals are mainly in their 20s or younger. It has increased or slightly increased in all age groups. The use rate of beds is slightly less than 10%. In Gifu, Shizuoka and Mie, the ratios of this week to last week are more than 1 (1.21, 1.29, and 1.29, respectively), with the number of new cases of infection at approximately 75, 54, and 75. The use rates of beds are slightly less than 10% in Gifu, less than 10% in Shizuoka, and slightly more than 10% in Mie.

  5. Kansai area

    In Osaka, the number of new cases of infection is approximately 117, with a ratio of this week to last week of more than 1 (1.33). The individuals are mainly in their 20s or younger. The number leveled off in those in their 80s and older and increased slightly or increased in other age groups. The use rate of beds is slightly more than 10%, and the use rate of beds for severe cases is slightly less than 10%. In Kyoto, Hyogo and Wakayama,, the numbers of new cases of infection are 82, 86, and 77, respectively, with a ratio to that for the previous week of more than 1 (1.04, 1.21, and 1.53). In Shiga and Nara, the numbers of new cases of infection are approximately 75 and 54, with a ratio of this week to last week of less than 1 (0.98 and 0.97). The use rates of beds is slightly more than 10% in Kyoto, approximately 10% in Wakayama, slightly less than 10% in Shiga and Hyogo, and less than 10% in Nara.

  6. Kyushu

    In Fukuoka, the number of new cases of infection is approximately 110, with a ratio of this week to last week of more than 1 (1.20). The infected individuals are mainly in their 30s or younger. It has increased or slightly increased in all age groups. The use rate of beds is approximately 10%. In Saga, Nagasaki, Kumamoto, Oita, and Miyazaki, the numbers of new cases of infection are 187, 137, 227, 84, and 147, respectively, with a ratio of this week to last week of more than 1 (1.42, 1.16, 1.39, 1.34, and 1.53, respectively). In Kagoshima, the number of new cases of infection is approximately 148, with a ratio of this week to last week of less than 1 (0.99). The use rates of beds are slightly more than 10% in Saga, approximately 10% in Nagasaki, slightly more than 20% in Kumamoto, less than 10% in Oita and Miyazaki, and slightly more than 20% in Kagoshima.

  7. Okinawa

    The number of new cases of infection is the highest nationwide, at 650, with a ratio of this week to last week of more than 1 (1.15). The infected individuals are mainly in their 30s or younger. The number leveled off in those in their 60s, but increased in other age groups. In particular, the increase among those in their teens or younger is marked. The use rate of beds is approximately 40%, while the use rate of beds for severe cases is slightly less than 20%.

  8. Areas other than the above

    In Aomori, Shimane, Hiroshima, Yamaguchi, Ehime, and Kochi, the numbers of new cases of infection are approximately 129, 195, 82, 80, 107, and 111, respectively. The use rates of beds are slightly more than 20% in Aomori, and slightly more than 10% in Shimane, Hiroshima, Yamaguchi, Ehime, and Kochi.

Future outlook and measures to be taken

  • Infection status
    • The number of newly infected individuals has turned upward nationwide (29 prefectures have a ratio to the previous week exceeding 1). By region, although still decreasing in some regions (decreased in 18 prefectures), the level generally showed an increasing trend in large cities. In some areas, the rate of increase is high. Okinawa has a higher level of infection than other regions and is on an upward trend, so it is necessary to pay particular attention to future trends in infection status.

    • The number of new cases of infection by age group slightly increased in almost all age groups nationwide. In addition, the increase in those in their 20s is large in Tokyo. In Okinawa, the number is increasing in all age groups, but as it is increasing even in the elderly, it is necessary to pay close attention to the infection situation.

    • The proportion of new cases of infection at schools continues to decrease, but the proportion remains high. In addition, the proportion at home is decreasing.

    • Regarding the future infection situation, the number of new cases of infection is expected to increase in large cities; (1) the immunity acquired by the third vaccination and infection will gradually decrease, (2) an increase in contact is expected after July due to the influence of after the rainy season, three consecutive holidays and summer vacation, and (3) since there is a possibility that the Omicron variant will be replaced by a new lineage, it will be necessary to pay close attention to the impact on the medical care provision system.

  • Factors that increase and suppress infection
    1. It is thought that infection status is affected by the following changes in factors that increase and suppress infection.

    1. [Contact patterns]

      The nighttime population is showing an increasing trend in many regions, mainly in large cites. Since in some areas the number approaches or exceeds the peak at the end of last year, it is necessary to pay attention to the impact on the infection status.

    2. [Epidemic strains]

      The BA.1 lineage has been replaced by the BA.2 lineage, but the new lineages BA.2.12.1, BA.4, and BA.5 lineages have been detected in Japan. In particular, the BA.5 lineage may become the mainstream lineage in Japan in the future, and could be a factor in increasing the number of infected people.

    3. [Vaccination]

      The third vaccination is proceeding, but it should be noted that as a certain period elapses after the third vaccination, the preventive effect against infection is expected to diminish from those who received vaccination earlier. In addition, the immunity acquired from previous infections is expected to gradually decline in the future.

    4. [Climatic factors]

      It is a time when indoor activities increase due to rising temperatures, but ventilation may be difficult because air conditioning is prioritized.

  • Medical care provision system
    • Nationwide, the use rate of beds is generally low, but as the number of newly infected individuals begins to rise, it has stopped decreasing in large cities. In Okinawa, the number of inpatients and the use rate of beds has leveled off or slightly increased, and the use rate of beds for severe cases is also increasing.

    • In cases of difficult emergency transportation, recently there is an increasing trend nationwide for both suspected non-COVID-19 cases and suspected COVID-19 cases. In addition, it is expected that the number of emergency transports due to heat stroke will increase, so careful attention should be paid.

  • Efforts based on the spread of infection with the Omicron variant
    1. [Surveillance, etc.]

      It is necessary to consider effective and appropriate surveillance, in order to properly grasp trends regarding occurrences. In addition, it is necessary to continue monitoring the trends of variants through genomic surveillance. For severe cases, clusters, and other applicable cases, confirmation via PCR testing for mutant strains and a whole-genome analysis is required.

    2. [Efforts by local governments]
      1. The number of new cases of infection is on the rise nationwide, and it is necessary for local governments to inspect the medical care/testing system and public health center system.

      • It is necessary to re-establish the required system for providing medical care based on the regional infection status.
      • When strengthening and thoroughly implementing a medical care support system for the elderly, it is important for medical and nursing care departments to cooperate, and proceed in consultation with local concerned parties.
      • Based on administrative notices such as to prioritize health observation and improve efficiency in processing notices of the occurrence of patients, in order to efficiently carry out public health center operations and maintain the public health center functions required in the region, it is important to secure a system for outsourcing or centralization at the main office.
      • Recently, effective and less burdensome measures against infection in medical and nursing care settings have been seen, and while knowledge about the risk of infection and infection control has accumulated, it is important to consider reasonable measures against infection according to the actual conditions at each facility.
    3. [Provision of information to unvaccinated individuals, and those receiving the third or fourth vaccination, etc.]
      • It is important for local governments to promote the provision of information on vaccination. The third and fourth vaccinations must also be steadily implemented, along with vaccinations for unvaccinated persons. The main purpose of the third vaccination is prevention of onset and aggravation. As of June 29, the rate of third vaccinations was about 90% for the elderly aged 65 years and older, and about 62% overall. It is necessary to steadily implement a third vaccination in subjects, and to vaccinate as many desiring recipients as possible. A fourth vaccination was started to prevent aggravation in persons aged 60 years and older, persons with underlying diseases at high risk of severe symptoms, and other persons deemed by doctors to be at a high risk of severe symptoms. It also became possible to start administration of a new vaccine for the first to third doses. This vaccine is different from the previous new coronavirus vaccine and can ensure a diversity of vaccines. It is also manufactured in Japan, ensuring the stability of vaccine supply.
      • Vaccination of children from 5 to 11 years old is being implemented as a special temporary vaccination, and it is necessary to promote vaccination, considering that the obligation to make efforts does not apply to these children. In hope of preventing infections in children, it is also important for parents and the adults around them to be vaccinated a third time.
    4. [Quarantine measures]

      It is necessary to verify the step-by-step review of quarantine measures, while taking into account the status of the current epidemic situation overseas and in Japan. In addition, while continuing pre-departure tests and responding to the risk of inflow, whole genome analysis should be continued for those who are positive in the immigration test to monitor strains circulating overseas.

  • Strengthening and thorough implementation of infection prevention measures based on the characteristics of the Omicron variant
    1. In situations and places where infection is widespread, it is necessary to strengthen and thoroughly implement infection control measures, based on the characteristics of the Omicron variant.

    • In schools, kindergartens, nursery schools, etc., infection control measures including active promotion of vaccinations for teachers and nursery teachers will be thoroughly implemented, as well as infection control measures for children, while sharing situations where the risk of infection in children and students increases with staff, children, parents, etc. It is also necessary to continue educational activities and social functions as far as possible. It is important to establish an environment where children and workers can take a leave of absence, in the case of any poor health conditions. At the same time, thorough infection control measures are also required at home. Masks are not recommended for children under 2 years of age, and for preschool children over 2 years of age, there are concerns about the risk of heat stroke and the effects of difficulty in seeing facial expressions. Therefore, it is necessary to thoroughly inform nursery schools, etc. that masks are not uniformly required, and that children should not be forced to wear them. Schools must be thoroughly informed that it is not necessary to wear a mask during physical education classes, athletic club activities, or when going to and from school.
    • It is necessary to take thorough measures at nursing care facilities, in order to control infections in the elderly. Therefore, workers are actively examined. In order to prevent aggravation, the fourth vaccination of residents will proceed. Further, it is important to secure external support systems for infection control and medical care at facilities, and to promptly intervene when infection is confirmed at facilities.
    • In the workplace, in order to maintain social functions, in addition to utilizing business continuity plans, efforts are required to utilize telework and promote the taking of time off. In addition, thorough health management of employees and securing an environment where they can take a leave of absence if they are even a little unwell are necessary. In addition, a third vaccination in the workplace should be actively promoted.
  • It is essential to widely share the current infection status with citizens and business operators, and cooperate toward preventing the spread of the infection.
    1. Nationwide, the number of new cases of infection has started to increase. The number of contacts is expected to increase due to the three consecutive holidays and summer vacation. For this reason, in order to minimize the increase in the number of cases of infection, it is necessary to thoroughly implement basic infection control measures and daily health management and cooperate in efforts to reduce the risk of infection.

    2. [Vaccination]

      In preparation for the spread of infection, a fourth vaccination is recommended for the elderly and those at risk of severe illness. It is important for people to receive the third vaccination, regardless of type. People with the novel coronavirus disease may experience severe conditions even if they are young, and may also suffer from prolonged symptoms. Accordingly, it is necessary to promote vaccinations not only in the elderly, but also in younger persons, in order to protect their health. It is important to consider vaccination again for people who have not received the first or second vaccination.

    3. [Thorough infection control]

      As basic infection control measures, it is necessary to continue to ensure the proper wearing of nonwoven masks, hand washing, ventilation, etc. The risk of infection becomes highest when the three Cs (crowded places, closed spaces, and close contact) overlap. However, even a single C should be avoided as much as possible.

    4. [When going out]

      Crowded or poorly ventilated places with a large number of people and loud voices, where the risk of infection is high, should be avoided. Activities with other persons should be carried out in a small group of people who usually meet each other. Eating and drinking together should be done in a small group without speaking to the extent possible, and masks should be worn at all times except while eating and drinking. On the other hand, the use of a mask is not necessary outdoors, except when talking at a close distance. Especially in summer, removing the mask outdoors is recommended from the viewpoint of preventing heat stroke.

    5. [Health management]

      It is necessary to refrain from going out if you feel a little unwell, such as a mild fever or fatigue, and to consult with a physician and undergo tests according to local government policy. In particular, caution should be exercised when meeting persons who are at a high risk of severe illness, such as the elderly.

<< Reference: Findings on the characteristics of the Omicron variant >>
  1. [Infectivity/transmissibility]

    It has been confirmed that compared to the Delta variant, the generation time has shortened to approximately 2 days (approximately 5 days for Delta). The doubling time and incubation period have also shortened, the risk of re-infection and secondary infection after infection has increased, and the speed of infection spread is very fast. According to the reported data, pre-symptomatic transmission has probably occurred to some extent as with the previous strains.

  2. [Place/route of infection]

    In Japan, many cases of infection have occurred through the same opportunities as before (spending time indoors in locations with inadequate ventilation, eating and drinking, etc.), and infection is considered to have occurred via the same routes as before (droplets adhering to mucosa, aerosol inhalation, contact infection, etc.).

  3. [Severity]

    It has been suggested that infection with the Omicron variant presents a lower risk of hospitalization or aggravation than the Delta variant. However, analyses to date show that the fatality due to infection with the Omicron variant is higher than that due to seasonal influenza. It is also suggested that the incidence of pneumonia is higher than that of seasonal influenza, but given the limited data, it needs to be investigated by various analyses. People aged 80 years and older account for a larger proportion of deaths in this wave of the spread of the infection than during last summer. It has been reported that there are many cases in which the new coronavirus infection is not the direct cause of death, for example, people who have been in a facility for the elderly before the infection are infected and die due to the worsening of the underlying disease. Attention should also be paid to worsening of the condition of elderly infected people and infected people with an underlying disease, and to the onset of heart failure and aspiration pneumonia.

  4. [Duration of viral shedding]

    Viral shedding in individuals infected with the Omicron variant decreases over time. In patients with symptoms, it has been shown that the possibility of viral shedding is low at 10 days after the date of onset. In patients with no symptoms, it has been shown that viral shedding does not occur 8 days after the date of diagnosis.

  5. [Vaccine effect]

    For infection with the Omicron variant, the preventive effects of a first vaccination against infection and disease onset are markedly reduced. Its preventive effect on hospitalization is reported to be maintained at a certain level for the first 6 months, but subsequently decreases to 50% or less. On the other hand, it has been reported overseas that a third vaccination restores the infection-preventing effect, onset-preventing effect, and hospitalization-preventing effect against infection by the Omicron variant, as well as information regarding how these vaccine effects are attenuated after a third vaccination.

  6. [Sublineage of Omicron variant]

    Currently, the BA.2 lineage remains the mainstream in Japan. Worldwide, the proportions of the BA.4 and BA.5 lineage are increasing, suggesting that these lineages are superior to the BA.2 lineage in terms of increasing the number of infected people. The number of positive tests is on the rise globally, as replacement by the BA.4 and BA.5 lineages proceeds. However, there are no clear findings on the infectivity of the BA.4 and BA.5 lineages.

    According to the WHO report, the findings accumulated from multiple countries indicate that there is no increase in the severity of the BA.4 and BA.5 lineages compared to existing Omicron variants.

    The BA.4 lineage and BA.5 lineage have both been detected in Japan and in quarantine. According to genomic surveillance, the BA.2 lineage continues to be the mainstream in Japan, but the detection rates of the BA.4 and BA.5 lineages may increase in the future. It is necessary to continue to collect and analyze the situation and findings in other countries regarding the characteristics of the virus, and to continue monitoring by genome surveillance.

Figures (Number of new infections reported etc.) (PDF)

 

88th Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (June 23, 2022). Material 1

 

Evaluation of the latest infection status, etc.

Infection status

  • Nationwide, the number of new cases of infection (by date of report) was about 78 per 100,000 in the last week, further decreasing to a ratio of this week to last week of 0.98, but the decrease is slowing down. The number of new cases of infection by age group continues to decrease in all age groups.
  • Along with the decrease in the number of new cases of infection nationwide, the numbers of patients receiving treatment, severe cases, and deaths also continue to decrease.

    Effective reproduction number: On a national basis, the most recent number is below 1, at 0.94 (as of June 5). The figure stands at 0.93 in the Tokyo metropolitan area and 0.95 in the Kansai area.

Local trends

* The value for new cases of infection is the number of persons per 100,000 among the total number for the latest week, based on reporting dates.

  1. Hokkaido

    The number of new cases of infection is approximately 90 (roughly 104 in Sapporo City), with a ratio of numbers for this week to last week of less than 1 (0.82). The infected individuals are mainly in their 30s or younger. It has slightly decreased or decreased in all age groups. The use rate of beds is slightly less than 10%.

  2. North Kanto

    In Ibaraki, the number of new cases of infection is approximately 51, with a ratio of this week to last week of more than 1 (1.08). The infected individuals are mainly in their 30s or younger. It slightly decreased among those in their 20s, 50s, and 70s, while it slightly increased or increased in other age groups. The use rate of beds is less than 10%. In Tochigi and Gunma, the numbers of new cases of infection are approximately 35 and 47, respectively, with a ratio of this week to last week of less than 1 (0.95 and 0.93). The use rate of beds is slightly less than 10% in Tochigi and Gunma.

  3. Tokyo metropolitan area (Tokyo and 3 neighboring prefectures)

    In Tokyo, the number of new cases of infection is approximately 86, with a ratio to the previous week of more than 1 (1.09). The infected individuals are mainly in their 30s or younger. It has slightly decreased or slightly increased in all age groups. The use rate of beds is slightly less than 10%, while the use rate of beds for severe cases is approximately 10%. In Saitama, Chiba, and Kanagawa, the numbers of new cases of infection are approximately 58, 50, and 61, respectively, with a ratio of this week to last week of more than 1 (1.09, 1.08, and 1.12). The use rates of beds are approximately 10% in Saitama, less than 10% in Chiba and slightly less than 10% in Kanagawa.

  4. Chukyo/Tokai

    In Aichi, the number of new cases of infection is approximately 73, with a ratio of this week to last week of less than 1 (0.95). The individuals are mainly in their 20s or younger. The number slightly increased in those in their 70s, and decreased slightly or decreased in other age groups. The use rate of beds is less than 10%. In Gifu and Shizuoka, he number of new cases of infection is approximately 62 and 42, respectively, with a ratio to the previous week of less than 1 (0.69 and 0.75). In Mie, the number of new cases of infection is approximately 58, with a ratio of this week to last week of more than 1 (1.04). The use rates of beds are slightly more than 10% in Gifu, less than 10% in Shizuoka, and approximately 10% in Mie.

  5. Kansai area

    In Osaka, the number of new cases of infection is approximately 88, with a ratio of this week to last week of less than 1 (0.93). The individuals are mainly in their 20s or younger. It has slightly decreased or decreased in all age groups. The use rate of beds is slightly more than 10%, and the use rate of beds for severe cases is slightly less than 10%. In Hyogo and Nara, the number of new cases of infection was approximately 71 and 56, respectively, with a ratio to the previous week of less than 1 (0.94 and 0.92). In Kyoto, the number of new cases of infection is approximately 79, with a ratio of this week to last week of 1.0. In Shiga and Wakayama, the numbers of new cases of infection are 76 and 50, respectively, with a ratio of this week to last week of more than 1 (1.05 and 1.01). The use rates of beds are slightly less than 10% in Shiga and Wakayama, less than 10% in Kyoto, approximately 10% in Hyogo, and slightly more than 20% in Nara.

  6. Kyushu

    In Fukuoka, the number of new cases of infection is approximately 92, with a ratio of this week to last week of less than 1 (0.99). The individuals are mainly in their 20s or younger. The number slightly increased in those in their 60s, and decreased slightly or decreased in other age groups. The use rate of beds is approximately 10%. In Oita, Miyazaki, and Kagoshima, the numbers of new cases of infection are approximately 62, 96, and 149, respectively, with a ratio of this week to last week of less than 1 (0.87, 0.92, and 0.95). In Saga, Nagasaki, and Kumamoto, the numbers of new cases of infection are 131, 118, and 163, respectively, with a ratio of this week to last week of more than 1 (1.09, 1.08, and 1.12). The use rates of beds are slightly less than 10% in Saga and Oita, approximately 10% in Nagasaki, slightly more than 20% in Kumamoto, less than 10% in Miyazaki, and slightly more than 10% in Kagoshima.

  7. Okinawa

    The number of new cases of infection is the highest nationwide, at approximately 567, with a ratio of this week to last week of less than 1 (0.98). The infected individuals are mainly in their 30s or younger. It has slightly decreased or decreased in all age groups. The use rate of beds is approximately 40%, and the use rate of beds for severe cases is approximately 10%.

  8. Areas other than the above

    In Aomori, Shimane, Hiroshima, Yamaguchi, Ehime, and Kochi the numbers of new cases, of infection are approximately 119, 67, 84, 62, 72, and 101, respectively. The use rates of beds are slightly more than 20% in Aomori, and slightly more than 10% in Shimane, Hiroshima, Yamaguchi, Ehime, and Kochi.

Future outlook and measures to be taken

  • Infection status
    • The number of new infections continued to decrease nationwide except in some regions, but the decrease is slowing down. By region, there are differences in the status of infection, with decrease continuing in some regions, and some showing signs of leveling off or increasing. In particular, in some small-population areas, the number of newly infected people is surging due to clusters of outbreak. In Okinawa, the decreasing trend in the number of infected people has continued, despite repeatedly leveling off or slightly increasing, but it has been increasing for the past few days, and the number of infected people per population continues to be higher than in other areas. Therefore, it is necessary to pay particular attention to future trends in infection status.

    • The number of new cases of infection by age group has continued to decrease or decrease slightly in all age groups nationwide, and a similar trend seen by region, although there are regions where increases can be seen at some ages.

    • The proportion of new cases of infection at schools is decreasing, but the proportion remains high. In addition, in the last few days, the proportion in nursery schools, etc. has been on the rise.

    • Regarding the future infection situation, although short-term forecasts for large cities do not anticipate a sharp increase, (1) the immunity acquired by the third vaccination and infection will gradually decrease, (2) an increase in contact is expected after July due to the influence of after the rainy season, three consecutive holidays and summer vacation, and (3) since there is a possibility that the Omicron variant will be replaced by a new lineage, it will be necessary to pay close attention to the impact on the medical care provision system.

  • Factors that increase and suppress infection
    1. It is thought that infection status is affected by the following changes in factors that increase and suppress infection.

    1. [Contact patterns]

      The nighttime population increases or decreases each week in some regions, while in other regions the number increases continuously. Since in some areas the number approaches or exceeds the peak at the end of last year, it is necessary to pay attention to the impact on the infection status.

    2. [Epidemic strain]

      The replacement by the BA.2 lineage has largely occurred and compared to the time when the BA.1 lineage was dominant, it may be a factor in a slowdown in the decrease. In addition, the BA.2.12.1 lineage, BA.4 linage, and BA.5 lineage have been detected in Japan, and it is necessary to continue monitoring.

    3. [Vaccination]

      The third vaccination is proceeding, but it should be noted that as a certain period elapses after the third vaccination, the preventive effect against infection is expected to diminish from those who received vaccination earlier. In addition, the immunity acquired from previous infections is expected to gradually decline in the future.

    4. [Climate factors]

      When the temperature rises, it becomes easier to ventilate, due to climate conditions. However, elevated temperatures and rainfall may increase indoor activities.

  • Medical care provision system
    • In Okinawa, the number of inpatients and the use rate of beds has leveled off or slightly increased, but the use rate of beds for severe cases is generally decreasing. Nationwide, due to the decreasing number of new cases, the use rate of beds has continued to decline, except in some regions.

    • In cases of difficult emergency transportation, the numbers are decreasing nationwide for both suspected non-COVID-19 cases and suspected COVID-19 cases.

  • Efforts based on the spread of infection with the Omicron variant
    1. [Surveillance, etc.]

      It is necessary to consider effective and appropriate surveillance, in order to properly grasp trends regarding occurrences. In addition, it is necessary to continue monitoring the trends of variants through genomic surveillance. For severe cases, clusters, and other applicable cases, confirmation via PCR testing for mutant strains and a whole-genome analysis is required.

    2. [Efforts by local governments]
      • Local governments also need to inspect the medical care/testing system and the public health center system in order to strengthen the response based on the characteristics of the Omicron variant.
      • It is necessary to continue efforts to establish the required system for providing medical care based on the regional infection status.
      • When strengthening and thoroughly implementing a medical care support system for the elderly, it is important for medical and nursing care departments to cooperate, and proceed in consultation with local concerned parties.
      • Based on administrative notices such as to prioritize health observation and improve efficiency in processing notices of the occurrence of patients, in order to efficiently carry out public health center operations and maintain the public health center functions required in the region, it is important to secure a system for outsourcing or centralization at the main office.
      • Recently, effective and less burdensome measures against infection in medical and nursing care settings have been seen, and while knowledge about the risk of infection and infection control has accumulated, it is important to consider reasonable measures against infection according to the actual conditions at each facility.
    3. [Provision of information to unvaccinated individuals, and those receiving the third or fourth vaccination, etc.]
      • It is important for local governments to promote the provision of information on vaccination. The third and fourth vaccinations must also be steadily implemented, along with vaccinations for unvaccinated persons. Individuals being vaccinated for the first time have also been reported to have a lower risk of prolonged symptoms.
      • The main purpose of the third vaccination is prevention of onset and aggravation. As of June 22, the rate of third vaccinations was about 90% for the elderly aged 65 years and older, and about 61% overall. It is necessary to steadily implement a third vaccination in subjects, and to vaccinate as many desiring recipients as possible. A fourth vaccination was started to prevent aggravation in persons aged 60 years and older, persons with underlying diseases at high risk of severe symptoms, and other persons deemed by doctors to be at a high risk of severe symptoms. It also became possible to start administration of a new vaccine for the first to third doses. This vaccine is different from the previous new coronavirus vaccine and can ensure a diversity of vaccines. It is also manufactured in Japan, ensuring the stability of vaccine supply.
      • Vaccination of children from 5 to 11 years old is being implemented as a special temporary vaccination, and it is necessary to promote vaccination, considering that the obligation to make efforts does not apply to these children. In hope of preventing infections in children, it is also important for parents and the adults around them to be vaccinated a third time.
    4. [Quarantine measures]

      It is necessary to verify the step-by-step review of quarantine measures, while taking into account the status of the current epidemic situation overseas and in Japan. In addition, while continuing pre-departure tests and responding to the risk of inflow, whole genome analysis should be continued for those who are positive in the immigration test to monitor strains circulating overseas.

  • Strengthening and thorough implementation of infection prevention measures based on the characteristics of the Omicron variant
    1. In situations and places where infection is widespread, it is necessary to strengthen and thoroughly implement infection control measures, based on the characteristics of the Omicron variant.

    • In schools, kindergartens, nursery schools, etc., infection control measures including active promotion of vaccinations for teachers and nursery teachers will be thoroughly implemented, as well as infection control measures for children, while sharing situations where the risk of infection in children and students increases with staff, children, parents, etc. It is also necessary to continue educational activities and social functions as far as possible. It is important to establish an environment where children and workers can take a leave of absence, in the case of any poor health conditions. At the same time, thorough infection control measures are also required at home. Masks are not recommended for children under 2 years of age, and for preschool children over 2 years of age, there are concerns about the risk of heat stroke and the effects of difficulty in seeing facial expressions. Therefore, it is necessary to thoroughly inform nursery schools, etc. that masks are not uniformly required, and that children should not be forced to wear them. Schools must be thoroughly informed that it is not necessary to wear a mask during physical education classes, athletic club activities, or when going to and from school.
    • It is necessary to take thorough measures at nursing care facilities, in order to control infections in the elderly. Therefore, workers are actively examined. In order to prevent aggravation, the fourth vaccination of residents will proceed. Further, it is important to secure external support systems for infection control and medical care at facilities, and to promptly intervene when infection is confirmed at facilities.
    • In the workplace, in order to maintain social functions, in addition to utilizing business continuity plans, efforts are required to utilize telework and promote the taking of time off. In addition, thorough health management of employees and securing an environment where they can take a leave of absence if they are even a little unwell are necessary. In addition, a third vaccination in the workplace should be actively promoted.
  • It is essential to widely share the current infection status with citizens and business operators, and cooperate toward preventing the spread of the infection.
    1. Although the number of new infections continues to decrease nationwide, the level of infection remains high, and in some areas it has leveled off or is showing signs of increase. For this reason, it is necessary to thoroughly implement basic infection control measures and daily health management, and cooperate in efforts to reduce the risk of infection.

    2. [Vaccination]

      It is important for people to receive a third vaccination as soon as possible, regardless of type, once such vaccination becomes available. People with the novel coronavirus disease may experience severe conditions even if they are young, and may also suffer from prolonged symptoms. Accordingly, it is necessary to promote vaccinations not only in the elderly, who have a risk of aggravation of symptoms, but also in younger persons, in order to protect their health. It is also important to consider vaccination again for people who have not received the first or second vaccination.

    3. [Thorough infection control]

      As basic infection control measures, it is necessary to continue to ensure the proper wearing of nonwoven masks, hand washing, ventilation, etc. The risk of infection becomes highest when the three Cs (crowded places, closed spaces, and close contact) overlap. However, even a single C should be avoided as much as possible.

    4. [When going out]

      Crowded or poorly ventilated places with a large number of people and loud voices, where the risk of infection is high, should be avoided. Activities with other persons should be carried out in a small group of people who usually meet each other. Eating and drinking together should be done in a small group without speaking to the extent possible, and masks should be worn at all times except while eating and drinking. On the other hand, the use of a mask is not necessary outdoors, except when talking at a close distance. Especially in summer, removing the mask outdoors is recommended from the viewpoint of preventing heat stroke.

    5. [Health management]

      It is necessary to refrain from going out if you feel a little unwell, such as a mild fever or fatigue, and to consult with a physician and undergo tests according to local government policy. In particular, caution should be exercised when meeting persons who are at a high risk of severe illness, such as the elderly.

<< Reference: Findings on the characteristics of the Omicron variant >>
  1. [Infectivity/transmissibility]

    It has been confirmed that compared to the Delta variant, the generation time has shortened to approximately 2 days (approximately 5 days for Delta). The doubling time and incubation period have also shortened, the risk of re-infection and secondary infection after infection has increased, and the speed of infection spread is very fast. According to the reported data, pre-symptomatic transmission has probably occurred to some extent as with the previous strains.

  2. [Place/route of infection]

    In Japan, many cases of infection have occurred through the same opportunities as before (spending time indoors in locations with inadequate ventilation, eating and drinking, etc.), and infection is considered to have occurred via the same routes as before (droplets adhering to mucosa, aerosol inhalation, contact infection, etc.).

  3. [Severity]

    It has been suggested that infection with the Omicron variant presents a lower risk of hospitalization or aggravation than the Delta variant. However, analyses to date show that the fatality due to infection with the Omicron variant is higher than that due to seasonal influenza. It is also suggested that the incidence of pneumonia is higher than that of seasonal influenza, but given the limited data, it needs to be investigated by various analyses. People aged 80 years and older account for a larger proportion of deaths in this wave of the spread of the infection than during last summer. It has been reported that there are many cases in which the new coronavirus infection is not the direct cause of death, for example, people who have been in a facility for the elderly before the infection are infected and die due to the worsening of the underlying disease. Attention should also be paid to worsening of the condition of elderly infected people and infected people with an underlying disease, and to the onset of heart failure and aspiration pneumonia.

  4. [Duration of viral shedding]

    Viral shedding in individuals infected with the Omicron variant decreases over time. In patients with symptoms, it has been shown that the possibility of viral shedding is low at 10 days after the date of onset. In patients with no symptoms, it has been shown that viral shedding does not occur 8 days after the date of diagnosis.

  5. [Vaccine effect]

    For infection with the Omicron variant, the preventive effects of a first vaccination against infection and disease onset are markedly reduced. Its preventive effect on hospitalization is reported to be maintained at a certain level for the first 6 months, but subsequently decreases to 50% or less. On the other hand, it has been reported overseas that a third vaccination restores the infection-preventing effect, onset-preventing effect, and hospitalization-preventing effect against infection by the Omicron variant, as well as information regarding how these vaccine effects are attenuated after a third vaccination.

  6. [BA.2 lineage]

    Currently, the BA.1 lineage has been largely replaced by the BA.2 lineage. Worldwide, the number of infected patients has increased, while replacement with the BA.2 lineage is progressing. However, the number is currently decreasing. Analyses of the effective reproduction number, risk of domestic secondary infection, and other indices have shown that the infectivity of the BA.2 lineage is higher than that of the BA.1 lineage. The generation time in the BA.2 lineage was 15% shorter than that in the BA.1 lineage, indicating that the effective reproduction number was 26% higher. It has also been reported that, when comparing the severity of the BA.1 lineage and the BA.2 lineage, there is no difference in the actual risk of hospitalization or aggravation. In addition, a report from the UK indicates that there is no difference in the preventive effect of vaccination, between these two lineages.

  7. [XE, BA.4, BA.5 and BA.2.12.1 lineages]

    Worldwide, the proportions of the BA.2.12.1 lineage, BA.4 lineage, and BA.5 lineage are increasing, suggesting that these lineages are superior to the BA.2 lineage in terms of increasing the number of infected people.

    1. BA.2.12.1, BA.4, and BA.5 lineages:According to the WHO report, the findings accumulated from multiple countries indicate that there is no increase in the severity of the BA.2.12.1, BA.4, and BA.5 lineages compared to existing Omicron variant. The detection rates of the BA.4 and BA.5 lineages have increased in some countries and regions, and replacement of the BA.2 lineage is progressing.

    2. XE lineage (recombinant of BA.1 and BA.2 lineages):The WHO report indicated that the rate of increase in community-acquired infections was approximately 10% higher than that of the BA.2 lineage, but the number of infected people in the world continues to decrease.

    The BA.2.12.1 lineage, BA.4 lineage, BA.5 lineage, and XE lineage have all been detected in quarantine. According to genomic surveillance, the BA.2 lineage continues to be the mainstream in Japan, but the detection rates of the BA.2.12.1 lineage, BA.4 lineage, and BA.5 lineage may increase in the future. It is necessary to continue to collect and analyze the situation and findings in other countries regarding the characteristics of the virus, and to continue monitoring by genome surveillance.

Figures (Number of new infections reported etc.) (PDF)

 

Copyright 1998 National Institute of Infectious Diseases, Japan

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