75th meeting of the COVID-19 advisory boardof Ministry of Health, Labour and Welfare (March 9, 2022). Material 1

Evaluation of the latest infection status, etc

Infection status

• The number of new cases of infection nationwide (by date of report) continued to decrease to about 329 per 100,000 in the last week, with the ratio of this week to last week at 0.90. The number of newly infected people by age group continues to decrease in all age groups.
• Among the 18 prefectures that are currently under priority preventative measures, 15 of them continued to show a decrease in the number of new cases of infection, with a ratio of this week to last week of less than 1. On the other hand, among the 13 prefectures where application of priority measures was lifted by the deadline of the 6th of this month, Fukushima, Kochi, Saga and Miyazaki have a ratio of this week to last week of more than 1.
• Along with the decrease in the number of new infections nationwide, the number of patients receiving treatment is decreasing, and the numbers of severe cases and deaths have tended to decrease.

  Effective reproduction number: On a national basis, the most recent number is below 1 (0.95 as of February 20), while the figure stands at 0.95 in the Tokyo metropolitan area and 0.93 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.

< Areas under priority measures >

1. Hokkaido

   The number of new cases of infection was approximately 234 (about 317 in Sapporo City), with a ratio of this week to last week of less than 1 (0.82). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 40%.

2. Tohoku

   In Aomori, the number of new cases of infection increased to approximately 256, with a ratio of this week to last week of 1.09. They are mainly in their 30s or younger, with the number of those under 10 particularly increasing. The use rate of beds is slightly less than 50%.

3. North Kanto

   In Gunma, the number of new cases of infection is approximately 217, with a ratio of this week to last week of less than 1 (0.96). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 50%, while the use rate of beds for severe cases is slightly more than 20%. In Tochigi, the number of new cases of infection was approximately 201, with a ratio of this week to last week of less than 1 (0.81). In Ibaraki, the ratio of this week to last week increased to 1.13, with approximately 340 new cases of infection. The use rate of beds is slightly less than 40% in Ibaraki and slightly more than 30% in Tochigi.

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

   In Tokyo, the number of new cases of infection is approximately 497, with a ratio of this week to last week of less than 1 (0.88). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 50%, while the use rate of beds for severe patients is approximately 40%. In Saitama, Chiba, and Kanagawa, the number of new cases of infection was approximately 386, 376 and 452, respectively, with a ratio of this week to last week of less than 1 (0.90, 0.94 and 0.97). The use rate of beds is slightly more than 50% in Saitama, approximately 60% in Chiba and slightly more than 60% in Kanagawa. The use rate of beds for severe cases is slightly less than 20% in Saitama, slightly more than 10% in Chiba and slightly more than 30% in Kanagawa.

5. Hokuriku

   In Ishikawa, the number of new cases of infection is approximately 245, with a ratio of this week to last week of less than 1 (0.91). The infected individuals are mainly in their 30s or younger. In particular, it increased in teenagers, and the number of people under the age of 10 remained at a high level. The use rate of beds is slightly more than 30%.

6. Chukyo/Tokai

   In Aichi, the ratio of this week to last week was less than 1 (0.88), with the number of new cases of infection at approximately 373. 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 20%. In Gifu and Shizuoka, the ratio of this week to last week was less than 1 (0.82 and 0.90, respectively), and number of new cases of infection was approximately 200 and 239. The use rate of beds is slightly more than 40% in Gifu and Shizuoka.

7. Kansai area

   In Osaka, the number of new cases of infection was the highest in Japan (approximately 507), but with a ratio of this week to last week of less than 1 (0.79). 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 50%. In Kyoto and Hyogo, the number of new cases of infection was 353 and 399, respectively, with a ratio of this week to last week of less than 1 (0.83 and 0.90). The use rate of beds is slightly more than 60% in Kyoto and approximately 60% in Hyogo. The use rate of beds for severe cases is slightly more than 30% in Kyoto and slightly more than 20% in Hyogo.

8. Shikoku

   In Kagawa, the number of new cases of infection was approximately 281, with a ratio of this week to last week of less than 1 (0.99). 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 approximately 20%.

9. Kyushu

   In Kumamoto, the number of new cases of infection increased to approximately 252, with a ratio of this week to last week of 1.11. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 40%.

< Excepting Areas under priority measures >

1. Okinawa

   The number of new cases of infection has increased continuously to approximately 365, with a ratio of this week to last week of 1.13. The newly infected individuals are mainly in their 30s or younger, with the number of those in their 50s and younger increasing. The use rate of beds is slightly more than 40%, while the use rate of beds for severe cases is slightly more than 30%.

2. Areas other than the above

   In Miyagi, Akita, Yamagata, Fukushima, Fukui, Shimane, Yamaguchi, Ehime, Kochi, and Saga, the number of new cases of infection is approximately 193, 152, 130, 134, 350, 105, 153, 144, 193, and 293, respectively. All of these prefectures show an increase, with a ratio of this week to last week of more than 1. In Miyazaki the ratio of this week to last week was 1.0, about 140. In Iwate, Niigata, Toyama, Yamanashi, Nagano, Mie, Shiga, Nara, Wakayama, Tottori, Okayama, Hiroshima, Tokushima, Fukuoka, Nagasaki, Oita, and Kagoshima, the number of new cases of infection is approximately 149, 109, 304, 182, 118, 213, 386, 462, 174, 122, 202, 160, 236, 356, 175, 194, and 172, respectively. All of these prefectures had a ratio of this week to last week of less than 1. The use rate of beds is approximately 40% in Iwate and Miyazaki, slightly more than 30% in Miyagi, Yamagata, Fukushima, Nagano, Mie, Wakayama, Shimane, Tokushima, Ehime, Saga, and Oita, slightly less than 40% in Akita, Hiroshima, and Kochi, slightly more than 20% in Niigata, Fukui, Tottori, and Nagasaki, slightly less than 30% in Toyama, slightly more than 40% in Yamanashi, Okayama, Yamaguchi, and Kagoshima, slightly more than 70% in Shiga, approximately 60% in Nara, and slightly more than 50% in Fukuoka. The use rate of beds for severe cases is about 20% in Miyagi, Tokushima, and Ehime, slightly less than 70% in Nara, and slightly less than 30% in Kochi.

* The bed use rate and bed use rate for severe cases are shown on the website of the Cabinet Secretariat.

Future outlook and measures to be taken

• The number of newly infected people nationwide has continued to decrease, with the effective reproduction number and ratio of this week to last week at 1 or below, and the moving average for the last week also tends to decrease, but the speed is gradual. The proportion of teens and younger among newly infected patients continues to increase and remains high. The infection of the elderly at nursing care facilities also continues.
• In many areas where the infection level was high, the decreasing trend continued, but in the areas where the infection level was relatively low, the decreasing tendency was weak, and leveling off or increases were seen, and there are regional differences in the changes of the infection situation. In particular, the number of persons younger than 10 is often increasing in areas where the decline has stopped or there is increase.
• The nighttime population is increasing in some areas under priority measures. In some areas where the application of priority measures was lifted in late February, the nighttime population has decreased in the last week, but has increased from before the cancellation, and the number of newly infected people is also increasing.
• The current status of infection is different from the spread of infection last summer, which showed a continuous decreasing trend, and the decrease in the number of patients with new infection is slow. It is expected that the number of newly infected people will be at a high level for at least a while. It is necessary to pay attention to the possibility that the number will increase again by replacing the BA.2 lineage in the future, and to the impact of the end of the fiscal year on the infection situation.
• It has been pointed out that published data on the number of test-positive persons may deviate from the actual situation due to delay in reporting. In determining the epidemic status, it is important to continuously monitor other indicators (for example, as monitoring items in Tokyo, the number of consultations on pyrexia, the number of patients tested, the number of applications of Tokyo Rules for emergency medical care, the number of inpatients, and the number of severe cases).
• Even if the number of infected people nationwide continues to decrease, the number of inpatients may level off or decrease slowly in many areas. For the time being, there is a possibility that the medical care provision system for mild and moderate cases will be strained in many areas, and in some areas the use of beds for severe cases may remain high due to the number of elderly people with severe illness. People aged 80 years and older account for a large proportion of the deaths in this spread of infection. In the situation before infection, many elderly people are hospitalized at medical institutions or admitted to facilities for the elderly. There are not a few cases in which COVID-19 is not a direct cause of death, such as those who do not wish to receive invasive treatment or those who die without meeting the definition of severe due to worsening of the underlying disease. It is also necessary to pay attention to increase in the number of infected people who require hospitalization because the underlying disease is exacerbated by infection in the positive patients with the underlying disease, even if they do not have pneumonia caused by COVID-19 infection, and because the elderly infected people develop heart failure or aspiration pneumonia, etc.
• In cases of difficult emergency transportation, both non-COVID-19 suspected cases and COVID-19 suspected cases have been on a downward trend nationwide, but they are still at a high level in many areas, which puts a heavy burden on conventional medical care, especially emergency medical care.

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 occur through the same opportunities as before (spending time indoors with insufficient ventilation, eating and drinking, etc.), and infection is considered to occur via the same routes as before (droplets, aerosol inhalation, contact infection, etc.).

3. [Severity]

   It has been suggested that infection with the Omicron variant may present a relatively lower risk of hospitalization and aggravation than does the Delta variant. However, the number of cases of hospitalization due to the Omicron variant infection has already increased. The case fatality rate of infection with the Omicron variant analyzed at this time is considered to be higher than that of seasonal influenza. Although the limited data suggest that the incidence of pneumonia is higher than that of seasonal influenza, it needs to be investigated by various analyses.

4. [Duration of viral shedding]

   Viral shedding in individuals infected with the Omicron variant decreases over time, regardless of their vaccination status. It has been shown that viral shedding is less likely in symptomatic individuals after 10 days from the date of onset, and less likely in asymptomatic individuals after 8 days from the date of diagnosis.

5. [Vaccine effect]

   For infection with the Omicron variant, the preventive effect of a first vaccination against disease onset is markedly reduced, but its preventive effect on hospitalization is maintained to a certain extent. It has also been reported from overseas that booster vaccination restores the infection-preventing effect, onset-preventing effect, and hospitalization-preventing effect against Omicron variant infection, and the attenuation of vaccine effect after booster vaccination. In Japan, there is a preliminary report of a case-control study on the efficacy of SARS-CoV-2 vaccines against the Omicron variant by two and three inoculations, and findings on the vaccine effectiveness against the Omicron variant have been increasing.

6. [BA.2 lineage]

   In some areas overseas, the number of cases of infection with the BA.2 lineage is increasing. In Japan, the Omicron variant initially had an influx of BA.1 and BA.1.1 from overseas, but after that, BA.1.1 became the majority and is still the mainstream, but the BA.2 lineage has also been detected in quarantine and in Japan, and it is estimated that the replacement with the BA.2 lineage will progress in the future. In this case, the rate of increase (decrease) of the number of cases of infection may be affected. Analyses of the effective reproduction number, risk of 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. In comparing the severity of the BA.1 lineage and BA.2 lineage, some animal studies suggest that the BA.2 lineage may be more pathogenic, but it has also been reported that there is no difference in the actual risk of hospitalization or aggravation. A report from the UK also shows that there is no difference in the preventive effect of the vaccine. The risk of reinfection with the BA.2 lineage virus after infection with the BA.1 lineage virus is still unknown.

Efforts based on the spread of infection due to the Omicron variant

1. [Surveillance in areas where infection is rapidly spreading]

   Effective and appropriate surveillance must be considered in order to understand the trends of occurrence. Regarding the monitoring system for mutant strains, it is necessary to continue monitoring trends by genome surveillance in regions where a strain has been replaced with the Omicron variant. For severe cases, clusters, or other applicable cases, confirmation by PCR test for mutant strains and whole-genome analysis is required.

2. [Measures taken by local governments]

   Based on the infection status of the region and forecasts of the numbers of infected cases and severe cases, local governments must work flexibly to secure the required number of beds and healthcare professionals, secure the functions of public health centers, which are indispensable for local communities, along with support for strengthening the healthcare center system, and establish home-visit and online medical care systems for home care recipients. At that time, it is necessary to secure a system for prompt administration of oral therapeutic drugs and neutralizing antibody drugs, for patients at risk of developing severe disease, such as elderly patients and patients with underlying diseases.

   Since patients with acute diseases other than COVID-19 who require emergency transportation often appear during this period, attention should be given to the balance between medical care for COVID-19 and regular medical care. If the infection spreads rapidly, it will be necessary to secure prompt access to consultation and condition monitoring for those at a higher risk of developing severe disease. In addition, a system must be established that allows COVID-19 patients with an underlying disease to continue treatment for the underlying disease.

   Implementation of efficient public health center operations are required, based on the administrative notice, such as prioritization of health observation and streamlining the handling of patient outbreak notifications. In addition, the optimization of measures based on the characteristics of the epidemic strain needs to be examined. In particular, regarding the identification and waiting of close contacts, considering that the infection level is high and it takes time to identify close contacts at public health centers due to the epidemic of Omicron variant, it is necessary to consider strategies such as the target.

3. [Strengthening the provision of information to unvaccinated people and those receiving booster vaccinations]

   • Regarding the rate of third vaccination, it exceeded about 60% for the elderly aged 65 and older, and about 25% overall. However, in order to minimize the number of severe and fatal cases, especially in the elderly, and at the same time to ensure that the current infection situation is on a downward trend, in addition to proceeding quickly with inoculation of the elderly, booster vaccination should be advanced to subjects under the age of 65 as much as possible.

   • It is important for local governments to promote the provision of information on vaccination. Along with vaccination of unvaccinated individuals, booster vaccination six months or more after the initial vaccination will restore vaccine effectiveness against the Omicron variant as well, and therefore booster vaccination must also be steadily implemented. Vaccinated individuals have also been reported to have a lower risk of corona sequelae.

   • In addition, vaccination of children aged 5 to 11 has begun. Although it is being carried out as a special temporary vaccination, it is necessary to proceed with vaccination taking into account that the obligation to make efforts does not apply to these children. In anticipation of preventing infections in children, it is also important for parents and adults around them to be vaccinated.

4. [Quarantine measures]

   Together with implementing measures such as easing the waiting period for immigrants from March, it is necessary to continue to verify the step-by-step review of quarantine measures, taking into account the status of mutant strains such as the Omicron variant overseas and in Japan. For individuals found to be positive by an entrance test, a whole-genome analysis should continue to be performed, to monitor the strains that are spreading 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 Omicron variant.

• In many areas, the numbers of persons who are positive for the COVID-19 and in close contact with infected individuals are increasing at schools, kindergartens, nursery schools, etc. In addition to thorough measures to prevent infections in children, it is necessary to thoroughly implement infection control measures, including active promotion of vaccination of teachers, childcare workers, etc. It is also necessary to consider securing educational opportunities through multiple measures including staggered attendance and online lessons, and maintaining social functions. At the same time, infection control measures must also be thoroughly implemented at home.
• It is important to take thorough measures at nursing care facilities in order to control infection in the elderly. Therefore, promotion of booster vaccinations for residents and staff, as well as aggressive testing for staff is required. For infection control and medical care at facilities, external support is important.
• At workplaces, it is necessary to utilize business continuity plans, and to reduce staff attendance at workplaces and opportunities for contact by utilizing telework, promoting the taking of time off, and through other measures, so that social functions can be maintained. Thorough health management and active promotion of occupational booster vaccinations for workers are also needed.

It is essential to widely share the current infection status with citizens and business operators, and cooperate toward preventing the spread of infection.

• Basic preventative measures are still effective against infection with the Omicron variant. Therefore, administrative officers, business operators, and citizens should 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, because the Omicron variant is highly transmissible. Furthermore, it is important to receive a booster vaccination with the expectation of not only preventing aggravation/onset of the disease in individuals, but also of preventing infection in the surrounding people.
• When going out, it is necessary to avoid situations/places with a high risk of infection such as crowds, and large gatherings either with or without shouting/loud speaking in poorly ventilated spaces. 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 carried out in a small group, without speaking to the extent possible, in principle, and the wearing of masks should be ensured at all times, except while eating and drinking.
• In order to protect the lives of both ourselves and our families, and at the same time, to prevent the spread of infection due to the Omicron variant, it is necessary to refrain from going out if you feel a little unwell, such as a mild fever or fatigue, and to consult a physician and undergo tests according to government policy.
• Towards the end of the fiscal year, there will be more opportunities for many people to gather, such as graduation ceremonies, spring breaks, three consecutive holidays, and cherry blossom viewing. Since the spread of infection has been triggered by such opportunities in the past, infection control measures must be thoroughly implemented.

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