78th meeting of the COVID-19 advisory boardof Ministry of Health, Labour and Welfare (March 30, 2022). Material 1

Evaluation of the latest infection status, etc

Infection status

• The number of new cases of infection nationwide (by date of report) shows an increasing trend at approximately 240 per 100,000 in the last week, with a ratio to the previous week of 1.04, but attention must be paid to future trends because of the effects of last week’s consecutive holidays.
• Along with the decrease in the number of new cases of infection to date 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 0.95 (as of March 13). The figure stands at 0.95 in the Tokyo metropolitan area and 0.90 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 increased to approximately 214 (approximately 285 in Sapporo City), with a ratio to the previous week of 1.07.

   They are mainly people in their 20s. The use rate of beds is slightly more than 10%.

2. North Kanto

   In Ibaraki, the number of new cases of infection is approximately 269, with a ratio to the previous week of less than 1 (0.80). The individuals are mainly in their 20s or younger. The use rate of beds is slightly less than 30%. In Tochigi and Gunma, the number of new cases of infection increased to approximately 213 and 201, respectively, with a ratio to the previous week of 1.25 and 1.04. The use rate of beds is slightly more than 20% in Tochigi and slightly less than 40% in Gunma.

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

   In Tokyo, the number of new cases of infection increased to approximately 358, with a ratio to the previous week of 1.05. The individuals are mainly in their 20s or younger. The use rate of beds and the use rate of beds for severe cases are both slightly more than 20%. In Saitama, the number of new cases of infection increased to approximately 325, with a ratio to the previous week of 1.01. In Chiba and Kanagawa, the number of new cases of infection increased to approximately 265 and 277, respectively, with a ratio to the previous week of less than 1 (0.95 and 0.86). The use rate of beds is about 40% in Saitama, about 30% in Chiba and slightly more than 40% in Kanagawa. The use rate of beds for severe patients is approximately 20% in Kanagawa.

4. Chukyou/Tokai

   In Aichi, the number of new cases of infection increased to approximately 239, with a ratio to the previous week of 1.15. The individuals are mainly in their 20s or younger. The use rate of beds is approximately 30%. In Gifu and Mie, the number of new cases of infection increased to approximately 169 and 175, respectively, with a ratio to the previous week of 1.29 and 1.20. In Shizuoka, the number of new cases of infection was approximately 169, with a ratio to the previous week of less than 1 (0.93). The use rate of beds is slightly more than 20% in Gifu and Mie, and slightly less than 20% in Shizuoka.

5. Kansai area

   In Osaka, the number of new cases of infection increased to approximately 291, with a ratio to the previous week of 1.08. The individuals are mainly in their 20s or younger. The use rate of beds is slightly more than 30%, while the use rate of beds for severe patients is slightly less than 30%. In Shiga, Hyogo, and Wakayama, the number of new cases of infection increased to approximately 277, 240, and 125, respectively, with a ratio to the previous week of 1.03, 1.03 and 1.14. In Kyoto and Nara, the number of new cases of infection was approximately 215 and 189, respectively, with a ratio to the previous week of less than 1 (0.99 and 0.79). The use rate of beds is slightly less than 40% in Shiga, approximately 30% in Kyoto and Hyogo, slightly more than 30% in Nara, and approximately 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 increased to approximately 268, with a ratio to the previous week of 1.08. They are mainly people in their 20s. The use rate of beds is slightly less than 30%. In Saga, Nagasaki, Kumamoto, Oita, Miyazaki, and Kagoshima, the number of new cases of infection increased to about 235, 123, 161, 173, 154, and 232, respectively, with a ratio to the previous week of 1.34, 1.16, 1.02, 1.39, 1.18, and 1.71. The use rate of beds is approximately 20% in Saga, slightly more than 10% in Nagasaki, slightly more than 20% in Kumamoto and Oita, approximately 10% in Miyazaki, and slightly more than 30% in Kagoshima.

7. Okinawa

   The number of new cases of infection increased to the highest nationwide (approximately 394), with a ratio to the previous week of 1.35. 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

   In Aomori, Akita, Yamanashi, and Kagawa, the number of new cases of infection was 284, 185, 187, and 233, respectively, with a ratio to the previous week of 1.05, 1.40, 1.25, and 1.0. In Ishikawa, the number of new cases of infection was approximately 140, with a ratio to the previous week of 0.76. The use rate of beds is approximately 30% in Aomori, slightly less than 30% in Akita, slightly more than 10% in Ishikawa, slightly less than 50% in Yamanashi, and slightly more than 30% in Kagawa.

Future outlook and measures to be taken

• Infection status

  • On a national basis, the number of new cases of infection has been gradually decreasing for over a month, with both the ratio to the previous week and effective reproduction number at less than 1, but the weekly moving average of the last few days has been increasing. Attention should be paid to the effect of the consecutive holidays last week on the figures, and it is necessary to continue to monitor the infection situation to see if this increasing trend will lead to a rebound.

  • The proportion of newly infected patients in their 20s shows an increasing trend. The proportion of restaurants as the place of infection is increasing among people in their 20s. In the elderly, infections at nursing care facilities and medical facilities are continuing to occur. In Kagoshima and Okinawa, where an increasing trend is now seen, the increase among people in their 20s is particularly remarkable.

  • In Tokyo, the number of newly infected people in their 20s has shifted from decreasing to bottoming out. The number of consultations on pyrexia, etc. and the number of applications of the Tokyo rules for emergency medical care have leveled off, while the number of people tested has been on a decreasing trend, but the positive rate of tests has been on an increasing trend. Attention should be paid as there may be signs of rebound.

• Factors that increase and suppress infection

  1. The following changes in factors that increase and suppress infection are thought to affect the future infection status.

  1. [Contact pattern]

     The nighttime population has been increasing nationwide since the priority measures were lifted, and in some areas it has shown a rapid increase or a continuous increase in the past week. It will soon be time for cherry blossom viewing, thank-you parties, welcome and farewell parties, and in particular, the increase in the nighttime population can be a factor in increasing the number of newly infected people. On the other hand, there are also regions where the nighttime population is decreasing. Attention about children is required because, although contact at school will decrease during spring break, contact opportunities will increase in other places.

  2. [Epidemic strain]

     The progress of replacement by the BA.2 lineage may be a factor in increasing the number of newly infected individuals. In Europe, the replacement by the BA.2 lineage is progressing, and not only infected people but also severe cases and deaths are increasing in some countries (such as UK), so caution is required.

  3. [Vaccinations, etc.]

     The main purpose of the third vaccination is prevention of onset and aggravation. While the third vaccination is proceeding in elderly people, the vaccination rate is still low in young people. However, it is expected that vaccination will proceed by becoming the targets for vaccination. It should be noted that the protective effect against the Omicron variant is lower than that against the Delta variant, and the duration is short. The infection prevention effect of the third vaccination is expected to diminish over time. In addition, the retention of immunity due to previous infections may affect the trends of occurrence in the region.

  4. [Climate factors]

     As the temperature rises toward spring, it will become easier to ventilate the climate conditions. It is thought that reduction of the amount of time spent indoors has a certain effect on suppressing infection, but it should be noted that infection spread during this period last year.

• Medical care provision system

  • With the decrease in the number of newly infected people to date nationwide, the use rate of beds and the number of patients treated at home have continued to decrease, although there are regional differences. However, there are areas where the number of patients recovering at accommodations has stopped decreasing or has leveled off.

  • In cases of difficult emergency transportation, although the decreasing trend continues in both suspected non-COVID-19 cases and suspected COVID-19 cases, they are still at the same high level as last summer's peak. Attention should be given to the balance between medical care for novel coronavirus infections and regular medical care, especially in emergency medical care.

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 treatment of the underlying disease to continue even if the patient has a novel coronavirus infection.

   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 a third vaccination]

   • The rate of receiving a third vaccination has exceeded 80% for the elderly aged 65 years and older, and 40% overall. However, in order to minimize the number of severe and fatal cases, especially in the elderly, while at the same time expecting decreasing trends in infection status, it is necessary to steadily implement the third vaccination to the elderly and subjects under the age of 65, and to inoculate as many of those who desire it as possible. From March 25, individuals 12 to 17 years old were also subject to the third vaccination, which is carried out as a special temporary vaccination.

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

   • Vaccination of children from 5 to 11 years old is being implemented as a special temporary vaccination, and it is necessary to promote 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.

• At schools, kindergartens, and day-care centers, 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, thorough infection control measures are also required at home. During spring break, thorough infection control measures are also required at schools when tutoring/coaching.
• It is necessary to take thorough measures at nursing care facilities, in order to control infections in the elderly. Therefore, promotion of a third vaccination 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 third vaccination 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.

• The current number of new infections continues to be higher than the peak last summer. There is also concern about the possibility of rebound because the factors that increase and suppress infection will continue. Therefore, for the time being, it is necessary to continue to reduce the number of infected people as much as possible after recognizing that it is a transition period to normal times, and calling for basic infection control measures while taking the utmost caution. In addition, citizens and businesses must continue to cooperate in efforts to reduce the risk of infection so that the number of newly infected people does not rebound.
• 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 third 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 local government policy.
• As we enter the new 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.

<< Reference: 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 adhering to mucosa, 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. 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. People aged 80 years and older account for a larger proportion of deaths in this wave of the spread of the infection than during last summer. Many of these people had resided at medical or elderly facilities before they were found to be infected. It has been reported that not a few have died from causes other than novel coronavirus infection 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.

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 a third 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 a third 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, and they are reported to be mainly unvaccinated.

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