79th meeting of the COVID-19 advisory boardof Ministry of Health, Labour and Welfare (April 6, 2022). Material 1

Evaluation of the latest infection status, etc.

Infection status

• The number of new cases of infection nationwide (by date of report) decreased to about 259 per 100,000 in the last week, with a ratio of this week to last week of 1.08, and future trends should be watched closely. In addition, the number of new cases of infection by age group started to increase in all age groups, with particularly marked increases in those in their teens and 20s.
• With the increasing trend in the number of new cases of infection nationwide, the number of patients being treated has also turned to increase. However, along with the decrease in the number of new cases of infection up to now, the numbers of severe cases and deaths continue to decrease.

  Effective reproduction number: On a national basis, the most recent number is below 1 at 0.97 (as of March 20). The figure stands at 0.97 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.

1. Hokkaido

   The number of new cases of infection was approximately 251 (approximately 312 in Sapporo City), with a ratio to the previous week increasing to 1.17. They are mainly in their 20s, and the number of those in their teens and 20s tended to increase. The use rate of beds is slightly more than 10%.

2. North Kanto

   In Ibaraki, the number of new cases of infection increased to approximately 304, with a ratio to the previous week of 1.13. They are mainly in their 20s or younger, with those in their teens and younger particularly increasing markedly. The use rate of beds is approximately 20%. In Tochigi and Gunma, the number of new cases of infection was approximately 228 and 206, respectively, with a ratio of this week to last week of more than 1 (1.07 and 1.02). The use rate of beds is approximately 20% in Tochigi and slightly more than 30% in Gunma.

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

   In Tokyo, the number of new cases of infection is approximately 373, with a ratio to the previous week of more than 1 (1.04). They are mainly in their 20s or younger, with the number of those in their 20s particularly increasing. The use rate of beds and the use rate of beds for severe cases are both slightly more than 20%. In Saitama, Chiba, and Kanagawa, the number of new cases of infection is approximately 336, 300, and 290, respectively, and the ratio to the previous week increased to 1.03, 1.13, and 1.05. The use rate of beds is slightly less than 40% in Saitama, slightly more than 20% in Chiba, and slightly more than 30% in Kanagawa.

4. Chukyo/Tokai

   In Aichi, the number of new cases of infection is approximately 232, with a ratio to the previous week of less than 1 (0.97). They are mainly in their 20s or younger, with the number of those in their 20s particularly increasing. The use rate of beds is slightly more than 20%. In Gifu, Shizuoka and Mie, the ratio of this week to last week was more than 1 (1.11, 1.15, and 1.24, respectively), with the number of new cases of infection at approximately 188, 193 and 218. The use rate of beds is slightly more than 20% in Gifu and Mie, and approximately 20% in Shizuoka.

5. Kansai area

   In Osaka, the number of new cases of infection is approximately 282, with a ratio to that for the previous week of less than 1 (0.97). They are mainly in their 20s or younger, with the number of those in their 20s particularly increasing. The use rate of beds is slightly less than 30%, while the use rate of beds for severe cases is approximately 20%. In Shiga, Hyogo, and Nara, the ratio of this week to last week was less than 1 (0.82, 0.95 and 0.95, respectively), with the number of new cases of infection at approximately 228, 229 and 179. In Kyoto and Wakayama, the number of new cases of infection was 249 and 166, respectively, with a ratio of this week to last week of more than 1 (1.16 and 1.33). The use rate of beds is slightly less than 40% in Shiga, slightly more than 20% in Kyoto, Hyogo and Nara, and approximately 30% in Wakayama. The use rate of beds for severe cases is approximately 20% in Nara.

6. Kyushu

   In Fukuoka, the number of new cases of infection is approximately 302, with a ratio to the previous week of more than 1 (1.13). They are mainly people in their 20s. The use rate of beds is slightly more than 20%. In Saga, Nagasaki, Kumamoto, Oita, Miyazaki, and Kagoshima, the number of new cases of infection is about 302, 151, 212, 241, 258, and 299, respectively, with the ratio to the previous week increasing to 1.28, 1.22, 1.32, 1.39, 1.68, and 1.29. The use rate of beds is slightly more than 20% in Saga and Kumamoto, slightly more than 10% in Nagasaki, slightly less than 30% in Oita, approximately 20% in Miyazaki, and slightly less than 30% in Kagoshima.

7. Okinawa

   The number of new cases of infection is the highest nationwide at approximately 496, with a ratio to the previous week increasing to 1.26. The infected individuals are mainly in their 20s or younger. All age groups are increasing, but particularly those in their 20s or younger increased markedly. The use rate of beds is approximately 30%.

8. Areas other than the above

   In Aomori, Akita, Fukushima, Ishikawa, Yamanashi, Kagawa, and Ehime, the number of new cases of infection is approximately 252, 197, 187, 169, 204, 231, and 137, respectively. The use rate of beds is approximately 30% in Aomori, slightly more than 20% in Akita and Ehime, slightly more than 30% in Fukushima, slightly more than 10% in Ishikawa, slightly less than 40% in Yamanashi, and slightly less than 30% in Kagawa. The use rate of beds for severe cases is slightly more than 30% in Ehime.

Future outlook and measures to be taken

• Infection status

  1. In the number of new cases of infection nationwide, the ratio to the previous week and the moving average for the latest week have been increasing for over a week. Looking at data by region, while there are regions that show continuous increase, some regions have leveled off, so attention should be paid to future trends. Since the end of last year, while some regions have decreased to levels below the peak of the spread of infection, in some regions, it has started to rise without sufficiently decreasing from the peak, and there are differences in the changes of infection status. In particular, in prefectures such as Akita, Niigata and Kagoshima, the moving average for the latest week has already exceeded the peak of the spread of infection since the end of last year, so the spread of infection in rural areas should be watched carefully.

  • The number of new cases of infection by age group changed to increase in all age groups, with particularly marked increases in those in their teens and 20s. It should be noted that this tendency is strong in areas with continuous increase such as Kagoshima and Okinawa, and that the number of elderly people is also increasing.

  • The proportion of newly infected patients in their 20s shows an increasing trend. The proportion of restaurants as the place of infection has increased to about 7% among people in their 20s (about 2% for all ages). In the elderly, infections at nursing care facilities and medical facilities are continuing to occur.

  • The spread of infection thus far has tended to be prevalent in young people and then spread to the elderly. Currently, the third vaccination for the elderly is in progress, but it is necessary to pay attention to the future epidemic situation.

• Factors that increase and suppress infection

  1. The infection situation is affected by changes in factors such as the following that increase and suppress infection, but the increase in contact opportunities and the replacement by the BA.2 lineage are thought to have a strong influence on the current increase in the number of infected people.

  1. [Contact pattern]

     The nighttime population shows a continuous increasing trend, especially in urban areas. In some regions, the nighttime population increased to near its peak at the end of last year, and has tended to decrease in the last week. On the other hand, there are few areas where the nighttime population is continuously decreasing, and it is the time when cherry blossom viewing and welcome parties are held. In particular, the increase in the nighttime population can be a factor in increasing the number of newly infected people. It is important to note that children begin a new school year, and may have more opportunities for contact at school.

  2. [Epidemic strain]

     The replacement by the BA.2 lineage has progressed, which 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 nationwide, despite regional differences the bed usage rate has continued to decline, although it has begun to increase in some regions. In addition, the numbers of home care recipients and medical treatment adjustments are also increasing in some regions.

  • In cases of difficult emergency transportation, although the decreasing trend has further continued 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. [Efforts by local governments]

     • Local governments need to further improve the testing system in preparation for re-expansion of infection by the Omicron variant.

     • Based on the local infection status, it is necessary to continue to work to secure the required number of beds and medical staff, and to establish home-visit medical care and online medical care systems. 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.

     • Prompt medical care support systems must be strengthened and thoroughly implemented at facilities for the elderly. When establishing a medical care support system, it is important for medical and nursing care departments to cooperate, and proceed in consultation with local concerned parties.

     • Based on administrative notices such as to prioritize health observation and improve efficiency in processing notices of the occurrence of patients, a system for outsourcing or centralization at the main office shall be secured, in order to efficiently carry out public health center operations and maintain the public health center functions required in the region. In addition, in the identification and home quarantine of 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 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. 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.

     • In rural areas, the number of infected people is increasing. A system like that described above needs to be established in all regions.

  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 vaccinate 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]

     It is necessary to verify the step-by-step review of quarantine measures, while taking into account the status of the current epidemic situation 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 the beginning of the new year at schools, kindergartens, and day-care centers, in addition to thorough measures to prevent infections in children, it is necessary to reconfirm and 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.
  • 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. In addition, it is important to secure external support systems for infection control and medical care at facilities, and to promptly intervene when infection is confirmed at facilities.
  • 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 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.

  • The current number of new infections continues to be higher than the peak last summer. In addition, the possibility of rebound is a concern in the current infection situation. Therefore, it is necessary for citizens and businesses to cooperate to maintain the decreasing trend in the number of infections, calling for thorough basic measures against infection, and prevent a resurgence in new cases 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 actively 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.
  • Since a new fiscal year often involves the movement of people and training when joining the company or enrolling in school, it is necessary to continue to thoroughly implement infection control measures.

<< 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)