100th Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (September 21, 2022) Material 1

Evaluation of the latest infectious status, etc.

Overview of the infection status

• The number of new cases of infection nationwide (by date of report) continued to decrease to about 370 per 100,000 in the last week, with the ratio to the previous week at 0.71.
  Nationwide, the infection level was below the peak in February this year. However, attention should be paid to the impact of consecutive holidays on the infection status.
• With the number of new cases of infection decreasing, the number of patients being treated is also decreasing. The use rate of beds is also declining.
  Although the burden on the medical care provision system partially continues, the situation is improving.
  The numbers of severe cases and deaths continue to decrease.

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 344 (approximately 386 in Sapporo City), with a ratio to the previous week of 0.68. 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 roughly 353, 296, and 354, with ratios to the previous week of 0.82, 0.70 and 0.77, respectively.
   The use rates of beds are slightly more than 40% in Ibaraki, slightly more than 20% in Tochigi, and approximately 30% in Gunma.

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

   The number of new cases of infection in Tokyo was approximately 370, 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 slightly less than 30%, while the use rate of beds for severe cases is slightly more than 20%.
   In Saitama, Chiba, and Kanagawa, the numbers of new cases of infection were approximately 407, 349, and 315, with ratios to the previous week of 0.87, 0.80, and 0.82, respectively. The use rates of beds are slightly more than 30% in Saitama, about 30% in Chiba and about 40% in Kanagawa.

4. Chukyo/Tokai

   The number of new cases of infection in Aichi was approximately 408, with a ratio to the previous week of 0.68. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 50%.
   In Gifu, Shizuoka, and Mie, the numbers of new cases of infection were about 360, 368, and 515, with ratios to the previous week of 0.58, 0.67, and 0.94, respectively. The use rates of beds are slightly more than 30% in Gifu, approximately 30% in Shizuoka, and slightly less than 40% in Mie.

5. Kansai area

   The number of new cases of infection in Osaka was approximately 390, with a ratio to the previous week of 0.68. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 30%, while the use rate of beds for severe cases is less than 10%.
   In Shiga, Kyoto, Hyogo, Nara, and Wakayama, the numbers of new cases of infection were about 452, 409, 373, 417, and 364, with ratios to the previous week of 0.70, 0.72, 0.67, 0.72, and 0.66, respectively. The use rates of beds are slightly less than 40% in Shiga, slightly more than 30% in Hyogo and Wakayama, slightly less than 30% in Kyoto, and slightly more than 20% in Nara.

6. Kyushu

   The number of new cases of infection in Fukuoka was approximately 331, with a ratio to the previous week of 0.62. The infected individuals are mainly in their 30s or younger. The use rate of beds is approximately 30%.
   In Saga, Nagasaki, Kumamoto, Oita, Miyazaki, and Kagoshima, the numbers of new cases of infection were about 342, 298, 369, 329, 451, and 498, with ratios to the previous week of 0.56, 0.49, 0.61, 0.57, 0.59, and 0.62, respectively. The use rates of beds are slightly less than 40% in Oita, Kumamoto, and Nagasaki, slightly more than 30% in Kagoshima, and slightly more than 20% in Miyazaki and Saga.

7. Okinawa

   The number of new cases of infection was approximately 277, with a ratio to the previous week of 0.60. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 30%, while the use rate of beds for severe cases is about 20%.

8. Areas other than the above

   In Hiroshima and Kagawa, the ratios to the previous week were 0.80 and 0.81, respectively. The use rates of beds are about 40% in Kagawa, slightly less than 20% in Kochi, and slightly more than 10% in Yamanashi.

Infection status and future outlook

Infection status

• The number of new cases of infection continued to decrease in all regions, and nationwide the infection level was below the peak in February this year. However, the rate of decrease has slowed down in Tokyo and other metropolitan areas, and in areas where the February peak was relatively low, such as Tohoku, Hokuriku, Chugoku, and Shikoku, the infection level still exceeds that peak. Outbreaks in facilities for elderly people and medical facilities continue, although they are decreasing.
• The number of new cases of infection in each age group continues to decrease nationwide, but the number of patients under the age of 10 is larger than other age groups. In some regions, such as Tokyo and Saitama, the number of those in their teens increased. The number of new cases of infection among the elderly has also been decreasing, and the numbers of severe cases and deaths continue to decrease.
• As the provisional report on the deaths of children since January this year suggests, attention must be paid to the occurrence of severe cases and deaths associated with the increase in the number of infected children.
• Regarding the places of infection of newly infected people, due to the reopening of schools, an increasing trend continues in schools, etc., but it is currently decreasing. (Due to the emphasis on active epidemiological surveys, the route of infection is only understood in some cases [about 13%], and the effect of consecutive holidays should be noted.)

Future outlook

• Regarding future infection status, although there are regional differences and uncertainties, the decreasing trend may continue in many regions, but the rate of decrease may slow in some regions, based on the epi curve of the date of onset and short-term forecast in large cities. Attention should be paid to the impact of consecutive holidays on the infection status. In addition, there are concerns that the seasonal flu epidemic may be earlier than usual, and that new coronavirus infections may occur simultaneously.

Factors that increase and suppress infection

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 about the spread of infection among elderly people in the future.

2. [Contact patterns]

   Regarding the nighttime population, the tendency has been flat overall, despite increases in relatively many regions, and while the infection situation is improving in all regions, movements are uneven, with effects of the weather. Due to the effects of bad weather such as rain and typhoons, it is necessary to pay attention to the increase in contact opportunities with the three Cs indoors rather than outdoors.

3. [Epidemic strain]

   The BA.5 lineage has largely become mainstream and is replacing others. At present, there is no trend toward further replacement by other lineages.

4. [Climatic factors]

   In the future, ventilation may be difficult on days with high temperatures or heavy rainfall.

Status of the medical care provision system

• Nationwide, the burden on the outpatient examination system is evident, and the use rate of beds is decreasing due to the continued improvement of the infection situation, being under 50% in almost all areas. The use rate of beds for sever cases is also declining. In addition, the numbers of home care recipients and medical treatment adjustments are on a decreasing trend in all areas where the data is available.
• Nationwide, although the burden on the medical care provision system including general medical care partially continues, the situation is improving. In the field of nursing care, patients are being treated in facilities and infection among workers continues.

Measures to be taken

Basic concepts

• Regarding measures under the Infectious Disease Control Law, appropriate medical care will be provided to the elderly and persons at risk of severe illness, and the period of medical treatment of patients will be reviewed.
• During this transition, the spread of infections this summer will be reviewed, along with measures to deal with the current infection situation, and measures will be taken based on the assumption that infections may spread due to simultaneous epidemic of seasonal influenza this fall.
• Each citizen will be asked to take voluntary actions to prevent infection, and the strengthening and prioritization of the health care system will be promoted in order to protect those at high risk of becoming seriously ill, such as the elderly, and to ensure regular medical care.
• 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.

1. 1. Further promotion of vaccinations
   • Preparations must proceed by mid-October for vaccination with the "vaccine for the Omicron variant" for all persons aged 12 and over who have completed the first vaccination.
   • By mid-October, the vaccine used the 4th vaccination, which is administered for reasons such as a high risk of severe illness, will be switched from the conventional vaccine to the vaccine for the Omicron variant. The vaccination interval was set at 5 months, but it is necessary to consider shortening the vaccination interval in light of overseas trends, and to reach a conclusion by the end of October.
   • Those who have not received vaccination will be encouraged to consider getting the initial vaccination as soon as possible.
   • For children (ages 5 to 11), booster vaccinations will be promoted along with the initial 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.
   • Perform frequent tests (about 2 or 3 times a week for facility workers) for workers at facilities for 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.
   • Promote further utilization of antigen qualitative test kits, such as by online sales through OTC.
3. 3. Securing a medical care provision system

    

   • 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
   • Expansion and promotion of fever outpatient services, including the use of online medical care, etc., and further promotion of the development of a “fever outpatient self-examination system”
   • 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.
   • Ensuring that workplaces and schools do not require test certificates at the start of medical treatment
4. 4. Change of thinking about medical treatment and review of all-case notification
   • In the review of the nationwide notification of all cases that begins on the 26th, the health care system will be strengthened and prioritized to protect those who are at high risk of becoming seriously ill, and it is necessary to establish an environment where young people with mild symptoms who are not subject to notification can be assured of treatment at home.
5. 5. Review of home care period
   • Since the risk of infection remains in the shortened period of home care for those who test positive, they should monitor their own physical condition, such as measuring temperature, and take thorough measures against infection when going out. In addition, they must be asked to avoid contact with people who are at risk of becoming seriously ill, such as the elderly.
   • To allow the minimum necessary outings, such as shopping for groceries, after 24 hours have passed since symptoms have subsided or when there are no symptoms, it is necessary to take voluntary actions to prevent infection, such as wearing a mask when going out or coming into contact with people, keeping contact with people to a short period of time, and not using public transportation.
6. 6. Surveillance
   • Deterioration of the accuracy of current surveillance is a concern due to the limited scope of notification, prioritization of notification items, delays in testing and diagnosis/reporting due to many infections, 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.
7. 7. 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 to prevent insufficient ventilation due to the use of air conditioners (how to create airflow considering aerosols, installation of partitions that do not block airflow, etc.).
8. 8. 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. In the death toll from the previous outbreak compared to last summer's outbreak, 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. In the current spread of infection, the rate of severe cases has continued to decrease and the ratio of elderly people among hospitalized patients has increased compared to the previous summer, following the previous outbreak. Among the deaths in this outbreak, mechanical ventilation/nasal high flow use rates and steroid prescription rates have decreased compared to the previous outbreak.

   Among fatal cases in which endogenous death was identified in infected children, cases without underlying diseases were also found. Preliminary reports on the results of on-site investigations have stated that it is necessary to pay attention to neurological symptoms such as convulsions and disturbance of consciousness, and systemic symptoms other than respiratory symptoms such as vomiting and poor oral intake.

4. [Virus shedding period]

   According to Japanese data, risk of infection remains until 10 days after onset, and infectivity is high until 7 days after onset. Even after waiting for 5 days, 1/3 of patients are still shedding infectious viruses. On Day 8 (after waiting 7 days), most patients (approximately 85%) had not shed infectious virus, and it was reported that even in those who shed the virus, the amount of virus decreased to one-sixth after 7 days compared to the initial stage.

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 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. According to genomic surveillance in Japan, the detection rate of the BA.5 lineage has increased, and the previous dominant variant has largely been replaced with this lineage.

   In addition, the BA.2.75 lineage, which has been reported mainly in India since June, and the BA.4.6 lineage reported mainly in the US and UK, 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)