99th Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (September 14, 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) was about 520 per 100,000 in the last week, and the ratio to the previous week continued to decrease at 0.76, and nationwide the infection level was almost the same as the peak in February this year. However, in some areas, the decrease in the number of infected people has slowed down, and it is necessary to continue to pay attention to the impact of the reopening of schools after the summer vacation and the upcoming consecutive holidays on the infection situation.
• 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 is partly continuing, not only by COVID-19 but also general medical care, the situation has been improved.
  The number of severe cases continues to decrease, and the number of deaths has also started to decrease.

  Effective reproduction number: On a national basis, the most recent number is 0.89 (as of August 28), while the figure stands at 0.91 in the Tokyo metropolitan area and 0.89 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 508 (approximately 520 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 slightly more than 30%.

2. North Kanto

   In Ibaraki, Tochigi, and Gunma, the numbers of new cases of infection were roughly 430, 422, and 459, with ratios to the previous week of 0.77, 0.81 and 0.80, respectively. In Tochigi and Gunma, they were mainly in their 30s or younger. The use rates of beds are slightly more than 40% in Ibaraki, and slightly more than 30% in Tochigi and Gunma.

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

   The number of new cases of infection in Tokyo was approximately 468, with a ratio to the previous week of 0.81. 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 slightly more than 20%. In Saitama, Chiba, and Kanagawa, the numbers of new cases of infection were approximately 466, 434, and 384, with ratios to the previous week of 0.84, 0.80, and 0.87, respectively. The use rates of beds are slightly more than 40% in Saitama and Kanagawa and slightly more than 30% in Chiba.

4. Chukyo/Tokai

   The number of new cases of infection in Aichi was approximately 600, with a ratio to the previous week of 0.75. 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 about 622, 548, and 548, with ratios to the previous week of 0.78, 0.83, and 0.67, respectively. The use rates of beds are approximately 40% in Shizuoka and slightly more than 40% in Gifu and Mie.

5. Kansai area

   The number of new cases of infection in Osaka was approximately 573, 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 40%, while the use rate of beds for severe cases is about 10%. In Shiga, Kyoto, Hyogo, Nara, and Wakayama, the numbers of new cases of infection were about 647, 569, 558, 579, and 548, with ratios to the previous week of 0.83, 0.74, 0.74, 0.83, and 0.78, respectively. The use rates of beds are slightly more than 50% in Shiga, slightly more than 40% in Hyogo, Kyoto and Wakayama, and slightly more than 20% in Nara.

6. Kyushu

   The number of new cases of infection in Fukuoka was approximately 536, with a ratio to the previous week of 0.69. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 40%. In Saga, Nagasaki, Kumamoto, Oita, Miyazaki, and Kagoshima, the numbers of new cases of infection were about 615, 609, 602, 573, 768, and 807, with ratios to the previous week of 0.75, 0.63, 0.74, 0.73, 0.79, and 0.78, respectively. The use rates of beds are slightly more than 50% in Oita, slightly more than 40% in Nagasaki and Kagoshima, slightly less than 40% in Miyazaki, and slightly more than 30% in Saga and Kumamoto.

7. Okinawa

   The number of new cases of infection was approximately 462, with a ratio to the previous week of 0.56. 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 30%.

8. Areas other than the above

   Fukushima, Toyama, Fukui, and Shimane had ratios to the previous week of 0.80, 0.81, 0.85, and 0.81, respectively. The use rates of beds are slightly more than 40% in Aomori, Akita, Yamagata, Toyama, Ishikawa, Nagano, Okayama, Tokushima, and Kagawa.

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 almost the same as the peak in February this year. 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. The number of new cases of infection among the elderly has also been decreasing, the number of severe cases continues to decrease, and the number of deaths has started to decrease.
• A provisional report was made on the deaths of children since January this year. Attention must be paid to the occurrence of severe cases and deaths associated with the increase in the number of infected children.
• Regarding the place of contracting new infections, the rate of infections that develop at home has tended to be flat for all ages, but it is increasing especially for those in their 20s. Due to the reopening of schools, the number of infections continues to increase at schools. (It should be noted that due to the emphasis on active epidemiological surveys, the route of infection is only understood in some cases [~13%].)

Future outlook and factors that increase and suppress infection

• 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. It is necessary to pay attention to the impact of the resumption of school after the summer vacation and the upcoming consecutive holidays. In addition, there are concerns that the seasonal flu epidemic may be earlier than usual, and that new coronavirus infections may occur simultaneously.
• 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 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 many regions, and while the infection situation is improving in all regions, movements are uneven.

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]

   High temperatures are expected to continue in September, 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 evident, and the use rate of beds is decreasing due to the continued improvement of the infection situation, being under 50% in most 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. On the other hand, in the field of nursing care, patients are being treated in facilities and infection among workers continues.
• Regarding cases of difficulty in emergency transport, the trend of improvement continues nationwide. However, there are still regions with high levels.

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.
• Assuming that a large-scale spread of infection may occur again, 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.
   • Implement 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.
   • 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.
   • 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 reviewing the nationwide notification of all cases, 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.

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. 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 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)