77th meeting of the COVID-19 advisory boardof Ministry of Health, Labour and Welfare (March 23, 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 approximately 232 per 100,000 in the last week, with a ratio to that for the previous week of 0.79, but attention must be paid to the effect of consecutive holidays on the figures. The number of new cases of infection by age group continued to decrease in all age groups.
• In all 18 prefectures in which the application of priority measures was lifted, the ratio of this week to last week was 1 or less.
• Along with the decrease in the number of new cases of infection nationwide, the numbers of patients receiving treatment, severe patients, and deaths continued to decrease.

  Effective reproduction number: On a national basis, the most recent number is below 1 at 0.96 (as of March 7). The figure stands at 0.97 in the Tokyo metropolitan area and 0.92 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.

1. Hokkaido

   The number of new cases of infection is approximately 200 (approximately 266 in Sapporo City), with a ratio to that for the previous week of less than 1 (0.95). They are mainly people in their 20s. The use rate of beds is approximately 20%.

2. North Kanto

   In Ibaraki, the number of new cases of infection is approximately 338, with a ratio to that for the previous week of less than 1 (0.98). The infected individuals are mainly in their 20s or younger. The use rate of beds is approximately 30%. In Tochigi and Gunma, the number of new cases of infection was approximately 170 and 193, respectively, with a ratio of this week to last week of less than 1 (0.90 and 0.88). The use rate of beds is slightly more than 20% in Tochigi and approximately 40% in Gunma.

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

   In Tokyo, the number of new cases of infection is the highest in Japan (approximately 341); however, its ratio to that for the previous week is less than 1 (0.81). The infected individuals are mainly in their 20s or younger. The use rate of beds is slightly more than 30%, and the use rate of beds for severe cases is about 30%. In Saitama, Chiba, and Kanagawa, the number of new cases of infection is approximately 322, 280, and 322, respectively, with a ratio to that for the previous week of less than 1 (0.91, 0.81, and 0.76, respectively). The use rate of beds is approximately 40% in Saitama, slightly more than 30% in Chiba and slightly more than 40% in Kanagawa. The use rate of beds for severe cases is slightly more than 20% in Kanagawa.

4. Chukyou/Tokai

   In Aichi, the number of new cases of infection is approximately 207, with a ratio to that for the previous week of less than 1 (0.72). The infected individuals are mainly in their 20s or younger. The use rate of beds is approximately 40%. In Gifu, Shizuoka and Mie, the ratio of this week to last week was less than 1 (0.73, 0.81, and 0.76, respectively), with the number of new cases of infection at approximately 131, 181 and 146. The use rate of beds is slightly more than 30% in Gifu, slightly more than 20% in Shizuoka, and slightly less than 30% in Mie.

5. Kansai area

   In Osaka, the number of new cases of infection is approximately 269, with a ratio to that for the previous week of less than 1 (0.66). The infected individuals are mainly in their 20s or younger. The use rate of beds is approximately 50%, and the use rate of beds for severe cases is approximately 40%. In Shiga, Kyoto, Hyogo, Nara, and Wakayama, the number of new cases of infection was 270, 217, 233, 239, and 109, respectively, with a ratio of this week to last week of less than 1 (0.75, 0.73, 0.71, 0.64, and 0.75). The use rate of beds is approximately 50% in Shiga, slightly more than 40% in Kyoto, approximately 40% in Hyogo, slightly more than 40% in Nara, and slightly more than 20% in Wakayama. The use rate of beds for severe cases is slightly more than 30% in Nara.

6. Kyushu

   In Fukuoka, the number of new cases of infection is approximately 249, with a ratio of this week to last week of less than 1 (0.77). They are mainly people in their 20s. The use rate of beds is slightly more than 30%. In Saga, Nagasaki, Kumamoto, Oita, Miyazaki, and Kagoshima, the number of new cases of infection is about 175, 106, 158, 125, 130, and 136, respectively, with a ratio to that for the previous week of less than 1 (0.67, 0.67, 0.63, 0.77, 0.88, and 0.91). The use rate of beds is slightly more than 20% in Saga, approximately 20% in Nagasaki, approximately 30% in Kumamoto, slightly more than 20% in Oita, slightly less than 20% in Miyazaki, and slightly less than 40% in Kagoshima.

7. Okinawa

   The number of new cases of infection was approximately 291, with a ratio of this week to last week of 1.0. The newly infected individuals are mainly in their 20s or younger, and attention should be paid to an increasing trend among those in their 20s. The use rate of beds is slightly more than 20%.

8. Areas other than the above

   Among 18 prefectures in which the application of priority areas has been lifted, besides the above-mentioned 15 prefectures, Aomori, Ishikawa, and Kagawa had a ratio of this week to last week lower than 1 at 0.96, 0.79, and 0.78, respectively, with the number of new cases being approximately 271, 184, and 232. The use rate of beds is slightly less than 30% in Aomori and Ishikawa, and slightly more than 30% in Kagawa.

Future outlook and measures to be taken

• All priority measures, such as those for the prevention of the spread of disease, were lifted by the deadline of March 21. On a national basis, the number of new cases of infection has been gradually decreasing for over a month, with both a ratio to that for the previous week and an effective reproduction number of less than 1. Among newly infected individuals, the proportion of those in their teens or younger continues to increase, and remains at a high level. In the elderly, infections at nursing care facilities and medical facilities are continuing to occur. The proportion of restaurants as the place of infection for newly infected people is increasing among people in their 20s.
• A continuous decrease in the number of cases of infection is being seen in metropolitan areas that were previously at a high infection level. However, in areas that were previously at a relatively low infection level, the number has stopped decreasing or even begun to increase, showing a weak tendency toward a decrease. The change in infection status differs between areas.
• In the nighttime population, there was a decreasing trend in the Tokyo metropolitan area just before the lifting of priority measures, while in some other areas it has been increasing continuously. It will soon be time for cherry blossom viewing, thank-you parties, welcome and farewell parties, etc., and it is necessary to pay attention to the trend of the number of infected people, especially because of the possibility that the nighttime population will increase.
• The current status is different from the last summer’s status, which showed a continuous decreasing trend, and the number of newly infected cases has been decreasing moderately and is still at a high level. Attention should be paid to the possibility that the number will increase again as replacement by the BA.2 lineage continues, as well as the impact on infection status when priority measures are lifted, and spring breaks or the start of the new school/business year increase opportunities for people who rarely see each other to meet. Therefore, for the time being, with the utmost caution and recognizing that it is a transition period to normal conditions, it is necessary to ask for the cooperation of citizens and business operators to maintain the decreasing trend in the number of infections with thorough basic measures against infection and to prevent a resurgence in new cases of infection.
• With the decrease in the number of newly infected people nationwide, the use rate of beds and the number of patients treated at home have continued to decrease, although there are regional differences. However, in many areas where the number of new infections has stopped decreasing or has increased, the number of hospitalizations has leveled off or is moderately decreasing.
• In cases of difficult emergency transportation, although there is a decreasing trend, both suspected non-COVID-19 cases and suspected COVID-19 cases remain at high levels. Attention should be given to the balance between medical care for COVID-19 and regular medical care, especially for emergency medical care.
• People aged 80 years and older account for a large proportion of deaths in this wave of the spread of the infection. Many of these persons had resided at medical or elderly facilities before they were found to be infected. It has been reported that not a few of these elderly people have died from causes other than COVID-19 itself: some refused highly invasive treatments, while others did not meet the definition of severe disease, due to the worsening of an underlying disease, or other reasons. Attention should also be given to a possible increase in the number of infected individuals requiring hospitalization, as test-positive persons with an underlying disease may experience disease exacerbation due to infection, or elderly infected patients may develop other symptoms, such as heart failure and aspiration pneumonia, even in the absence of COVID-19 pneumonia.

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 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, aerosol inhalation, contact infection, etc.).

3. [Severity]

   It has been suggested that infection with the Omicron variant may present 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. Limited data also indicate that the incidence of pneumonia in infection with the Omicron variant is higher than that in seasonal influenza. Further investigations, using various analyses are needed.

4. [Duration of viral shedding]

   Viral shedding in individuals infected with the Omicron variant decreases over time. In patients with symptoms, it has been shown that the possibility of viral shedding is low 10 days after the date of onset. In patients with no symptoms, it has been shown that viral shedding does not occur 8 days after 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. 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 booster vaccination restores the infection-preventing effect, onset-preventing effect, and hospitalization-preventing effect against Omicron variant infection, as well as how these vaccine effects are attenuated after booster vaccination. Overseas, a fourth vaccination has been started in some countries. It is necessary to collect information on efficacy and safety, and to examine the need for a fourth vaccination in Japan, and the eligible persons, starting time, etc.

6. [BA.2 lineage]

   In some areas overseas, the number of cases of infection with the BA.2 lineage is increasing. In Japan, both the BA.1 lineage and the BA.1.1 lineage of the Omicron variant initially entered from overseas, after which the BA.1.1 lineage became the majority strain, and is still dominant. However, the BA.2 lineage has begun to be detected at quarantine stations and other domestic facilities, and replacement with the BA.2 lineage is progressing. Therefore, this may affect the pace of the increase (decrease) in the number of cases of infection. Analyses of the effective reproduction number, risk of domestic 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. In addition, a report from the UK indicates that there is no difference in the preventive effect of vaccination, between these two lineages. In the UK, a small number of cases of reinfection with the BA.2 lineage after infection with the BA.1 lineage have been reported, but the specific details of these cases are still unknown.

Efforts based on the spread of infection with the Omicron variant

1. [Surveillance, etc.]

   It is necessary to consider effective and appropriate surveillance, in order to properly grasp trends regarding occurrences. As a system of mutant strain monitoring, genomic surveillance should be continued in order to monitor the trend regarding replacement of the BA.1 lineage with the BA.2 lineage. For severe cases, clusters, or other applicable cases, confirmation via PCR testing for mutant strains and a whole-genome analysis is required.

2. [Measures taken by local governments]

   Based on the infection status in each area, local governments must continue to work on securing the required number of beds and healthcare professionals, securing the functions of public health centers, which are indispensable for local communities, along with support for strengthening the healthcare center system, and establishing home-visit and online medical care systems for home care recipients. It is still necessary to secure a system for prompt administration of oral therapeutic drugs and neutralizing antibody drugs, for patients with a risk of developing severe disease, such as elderly patients and patients with underlying diseases. It is also necessary to establish a system 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, in the identification and home quarantine on close contacts, it is necessary in principle to take appropriate measures against infections according to the local infection status, and taking into account the characteristics of Omicron variant (such as the short incubation period and interval of onset) and the status of the spread of infection, it is necessary to focus on the cases of infection at facilities such as medical institutions and elderly facilities where people at particularly high risk of severe disease are admitted. At the same time, it is important to establish an environment where people can take a break from work or school if they feel even a little unwell.

3. [Reinforcement of information provision to unvaccinated individuals and those receiving booster vaccinations]

   • The rate of receiving a third vaccination has exceeded approximately 76% for the elderly aged 65 years and older, and roughly 35% overall. However, in order to minimize the number of severe and fatal cases, especially in the elderly, while at the same time ensuring that the other infection indices take a downward turn, it is necessary to proceed promptly with vaccinations for the elderly, and to provide booster vaccinations ahead of the original schedule for eligible persons 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 the adults around them to be vaccinated.

4. [Quarantine measures]

   Together with measures such as shortening the waiting period for immigrants from March, it is necessary to continue to verify the step-by-step review of border quarantine measures, while taking into account the status of mutant strains overseas and in Japan. In particular, attention should be paid to the recent epidemic status in the East Asian region. For individuals who are 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 the active promotion of vaccination of teachers, childcare workers, etc. It is important to establish an environment where children and workers can take a leave of absence, in the case of any poor health conditions. 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 be thoroughly implemented at home. During spring breaks, thorough infection control measures are also required during tutoring/coaching at schools.
• It is important to take thorough measures at nursing care facilities, in order to control infections in the elderly. Therefore, promotion of booster vaccinations for residents and staff, as well as aggressive testing of staff is required. For infection control and medical care at facilities, prompt 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 adopting telework, promoting the taking of time off, and through other measures, so that social functions can be maintained. Thorough health management, the establishment of an environment where people can take a leave of absence, and the 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.

• Although all priority measures such as for prevention of spread of disease have been lifted, it is necessary to continue basic infection control measures, considering that the number of newly infected people is currently higher than the peak of last summer.
• 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 with 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 with a physician and undergo tests according to government policy.
• From the end of the fiscal year to the beginning of the next fiscal year, there will be more opportunities for many people to gather, such as spring break, cherry blossom viewing, and entrance ceremonies. Since the spread of the infection has been triggered by such opportunities in the past, infection control measures must be thoroughly implemented to prevent a future rebound. In addition, attention should also be paid to the fact that movement of people and training will become more frequent at the beginning of the fiscal year, as people will be newly joining companies and entering schools.

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