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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)

 

Copyright 1998 National Institute of Infectious Diseases, Japan