74th meeting of the COVID-19 advisory boardof Ministry of Health, Labour and Welfare (March 2, 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 364 per 100,000 in the last week, with the ratio of this week to last week at 0.84. The number of newly infected people by age group has shown a decreasing trend in all age groups.
• Among the 31 prefectures that are currently under priority preventative measures, 30 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. However, among 5 prefectures in which the application of priority measures was lifted, Shimane, Oita, and Okinawa have a ratio of this week to last week of more than 1.
• Although the number of patients receiving treatment is decreasing along with the decrease in the number of new infections nationwide, the numbers of severe cases and deaths remain high.

  Effective reproduction number: On a national basis, the most recent number is below 1 (0.97 as of February 13), while the figure stands at 0.96 in the Tokyo metropolitan area and 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 286 (about 391 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 approximately 40%.

2. Tohoku

   In Aomori, the number of new cases of infection is approximately 234, with a ratio of this week to last week of less than 1 (0.94). They are mainly in their 30s or younger, with the number of those under 10 particularly increasing. The use rate of beds is approximately 50%. In Fukushima, the number of new cases of infection was approximately 113 with a ratio of this week to last week of less than 1 (0.92). The use rate of beds is slightly less than 50%.

3. North Kanto

   In Gunma, the number of new cases of infection is approximately 227, 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 more than 50%, while the use rate of beds for severe cases is slightly more than 20%. In Ibaraki and Tochigi, the number of new cases of infection was approximately 301 and 248, respectively, with a ratio of this week to last week of less than 1 (0.93 and 0.88). The use rate of beds is slightly more than 40% in Ibaraki and slightly less than 40% in Tochigi. The use rate of beds for severe cases is approximately 20% in Ibaraki and Tochigi.

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

   In Tokyo, the number of new cases of infection is approximately 564, with a ratio of this week to last week of less than 1 (0.81). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 50%, while the use rate of beds for severe cases is slightly more than 40%. In Saitama, Chiba, and Kanagawa, the number of new cases of infection was approximately 428, 399 and 467, respectively, with a ratio of this week to last week of less than 1 (0.84, 0.81 and 0.84). The use rate of beds is slightly more than 50% in Saitama, slightly more than 60% in Chiba and approximately 70% in Kanagawa. The use rate of beds for severe cases is approximately 20% in Saitama and Chiba and slightly less than 40% in Kanagawa.

5. Chubu/Hokuriku

   In Ishikawa, the number of new cases of infection has increased continuously to approximately 268, 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 more than 30%. In Niigata and Nagano, the number of new cases of infection was approximately 133 and 119, respectively, with a ratio of this week to last week of less than 1 (0.88 and 0.77). The use rate of beds is slightly more than 20% in Niigata and slightly more than 30% in Nagano.

6. Chukyo/Tokai

   In Aichi, the ratio of this week to last week was less than 1 (0.84), with the number of new cases of infection at approximately 424. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 60%, while the use rate of beds for severe cases is approximately 30%. In Gifu, Shizuoka and Mie, the ratio of this week to last week was less than 1 (0.79, 0.95, and 0.87, respectively), with the number of new cases of infection at approximately 243, 266 and 229. The use rate of beds is slightly more than 40% in Gifu, slightly less than 50% in Shizuoka, and slightly more than 40% in Mie.

7. Kansai area

   In Osaka, the number of new cases of infection was the highest in Japan (approximately 638), but with a ratio of this week to last week of less than 1 (0.76). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 80%, while the use rate of beds for severe cases is slightly more than 50%. In Kyoto, Hyogo, and Wakayama, the number of new cases of infection was 426, 445, and 217, respectively, with a ratio of this week to last week of less than 1 (0.79, 0.79, and 0.78). The use rate of beds is slightly more than 70% in Kyoto, slightly less than 70% in Hyogo, and approximately 50% in Wakayama. The use rate of beds for severe cases is slightly more than 50% in Kyoto, and slightly more than 20% in Hyogo and Wakayama.

8. Chugoku/Shikoku

   In Hiroshima, the number of new cases of infection is approximately 173, with a ratio of this week to last week of less than 1 (0.91). They are mainly in their 30s or younger, with the number of those under 10 remaining particularly high. The use rate of beds is slightly more than 40%. The use rate of beds for severe cases is slightly more than 20%. In Okayama, Kagawa, and Kochi, the number of new cases of infection has also decreased to approximately 217, 283, and 178, respectively, with a ratio of this week to last week of less than 1 (0.86, 0.94. and 0.89). The use rate of beds is slightly more than 40% in Okayama, slightly less than 40% in Kagawa, and approximately 40% in Kochi. The use rate of beds for severe cases is slightly less than 30% in Kochi.

9. Kyushu

   In Fukuoka, the number of new cases of infection is approximately 406, with a ratio of this week to last week of less than 1 (0.85). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 60%. In Saga, Nagasaki, Kumamoto, Miyazaki, and Kagoshima, the number of new cases of infection is 289, 189, 227, 140, and 193, respectively, with a ratio of this week to last week of less than 1 (0.88, 0.98, 0.87, 0.97, and 0.93). The use rate of beds is approximately 30% in Saga, slightly less than 30% in Nagasaki, approximately 50% in Kumamoto, slightly more than 30% in Miyazaki, and approximately 40% in Kagoshima.

< Excepting Areas uner priority measures >

1. Okinawa

   The number of new cases of infection increased to approximately 324, with a ratio of this week to last week of 1.12. The newly infected individuals are mainly in their 30s or younger, with the number of those in their teens and younger particularly increasing. The use rate of beds is approximately 50%, and the use rate of beds for severe cases is approximately 40%.

2. Areas other than the above

   In Iwate, Akita, Toyama, Fukui, Tottori, Shimane, Tokushima, Ehime, and Oita, the number of new cases of infection is approximately 189, 150, 307, 284, 186, 92, 279, 125, and 199 , respectively. All of these prefectures show an increase, with a ratio of this week to last week of more than 1. In Miyagi, Yamagata, Yamanashi, Shiga, Nara, and Yamaguchi, the number of new cases of infection is 191, 122, 195, 451, 485, and 135, respectively, with a ratio of this week to last week of less than 1 (0.86, 0.91, 0.76, 0.95, 0.83, and 0.95). The use rate of beds is slightly less than 40% in Iwate and Akita, slightly more than 40% in Miyagi, slightly more than 30% in Toyama, Ehime and Oita, approximately 30% in Yamagata, slightly more than 20% in Fukui, Tottori and Shimane, slightly more than 50% in Yamanashi, slightly more than 70% in Shiga, slightly more than 60% in Nara, and approximately 40% in Yamaguchi and Tokushima. The use rate of beds for severe cases is approximately 70% in Nara.

* 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 has also continued to decrease for over a week, but considering the impact of last week's holidays, it is necessary to pay close attention to future trends. The reduction continues in many regions, including areas under priority measures, but is flat or increasing in some regions. In addition, the infection level in large urban areas remains high, and the tendency of improvement in the infection situation in rural areas is also weak. The proportion of newly infected individuals in their teens or younger remains high, and elderly people continue to be infected in nursing care facilities.
• In the current situation, unlike the spread of infection last summer, which showed a continuous decreasing trend with the acceleration of vaccination, the decrease in the number of patients with new infection is slow, and it is expected that the number of newly infected people will be at a high level for at least a while.
• The nighttime population is increasing in some areas under priority measures, and is also increasing rapidly in areas where priority measures have been lifted, such as Okinawa, and the number of newly infected people is also increasing. Although there are no signs of it yet, 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). In the positive rate of tests, there is a marked delay in reporting the number of tests, which is the denominator, and this should just be used as a reference.
• Even if the number of infected people nationwide continues to decrease, 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 the use of beds for severe cases will remain high due to the number of elderly people with severe illness. Elderly people account for a large proportion of the deaths in this spread of infection. It has been pointed out that some of the elderly die without meeting the definition of severe illness due to the effects of not desiring highly invasive treatment or the worsening of an underlying disease. Attention should also be given to an increase in the number of infected individuals requiring hospitalization, as test-positive persons with an underlying disease may require hospitalization due to disease exacerbation by the infection, or elderly infected patients developing pneumonia, including aspiration pneumonia, even in cases where they do not have COVID-19 pneumonia.
• In cases of difficult emergency transportation, both non-COVID-19 suspected cases and COVID-19 suspected cases have shown a slight downward trend in many regions, but are still increasing at a high level, 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. Currently, the mainstream of the Omicron variant in Japan is the BA.1 lineage, but the BA.2 lineage has also been detected in quarantine and in Japan, and its proportion may increase. 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 recently issued 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 infection with the Omicron variant has a short generation time and incubation period, the effect of preventing the spread of infection is limited in situations where the infection level is high and it takes time to identify close contacts at the public health center, so it is necessary to consider strategies such as target people.

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

   • The rate of a third vaccination in the elderly aged 65 years and older has reached about 50%. 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 further accelerating 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. Vaccination has also been reported to be effective against corona sequelae.

   • Vaccination of children from 5 to 11 years old is also necessary as a special temporary vaccination, and it is necessary to proceed with vaccination in the future 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. Local governments need to actively promote vaccination for teachers, childcare workers, and the other staff at such facilities. 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, and three consecutive holidays. 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)