87th Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (June 8, 2022). Material 1

Evaluation of the latest infection status, etc.

Infection status

• Nationwide, the number of new cases of infection (by date of report) was about 97 per 100,000 in the last week, further decreasing to a ratio of this week to last week of 0.70. The number of new cases of infection by age group continues to decrease in all age groups.
• Along with the decrease in the number of new cases of infection nationwide, the numbers of patients receiving treatment and severe cases continue to decrease, while the number of deaths, which had leveled off, has also started to decrease.

  Effective reproduction number: On a national basis, the most recent number is less than 1 (0.91, as of May 22), and the figure stands at 0.92 in both the Tokyo metropolitan and Kansai areas.

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 127 (roughly 140 in Sapporo City), with a ratio of numbers for this week to last week of less than 1 (0.65). The infected individuals are mainly in their 30s or younger. It decreased in all age groups. The use rate of beds is slightly more than 10%.

2. North Kanto

   In Ibaraki, the number of new cases of infection is approximately 56, with a ratio of numbers for this week to last week of less than 1 (0.66). The infected individuals are mainly in their 30s or younger. It decreased in all age groups. The use rate of beds is slightly less than 10%. In Tochigi and Gunma, the numbers of new cases of infection are approximately 48 and 54, respectively, with a ratio of numbers for this week to last week of less than 1 (0.71 and 0.65). The use rates of beds are less than 10% in Tochigi and approximately 10% in Gunma.

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

   In Tokyo, the number of new cases of infection is approximately 95, with a ratio of this week to last week of less than 1 (0.72). The infected individuals are mainly in their 30s or younger. It has slightly decreased or decreased in all age groups. The use rate of beds is slightly more than 10%, and the use rate of beds for severe cases is slightly less than 20%. In Saitama, Chiba, and Kanagawa, the numbers of new cases of infection are approximately 59, 54, and 70, respectively, with a ratio of this week to last week of less than 1 (0.63, 0.67, and 0.68). The use rates of beds are slightly more than 10% in Saitama, slightly less than 10% in Chiba and approximately 10% in Kanagawa.

4. Chukyo/Tokai

   In Aichi, the number of new cases of infection is approximately 106, with a ratio of this week to last week of less than 1 (0.72). The individuals are mainly in their 20s or younger. It has slightly decreased or decreased in all age groups. The use rate of beds is slightly more than 10%. In Gifu, Shizuoka and Mie, the ratio of this week to last week is less than 1 (0.80, 0.70, and 0.69, respectively), with the number of new cases of infection at approximately 132, 81, and 79. The use rates of beds are slightly less than 30% in Gifu, approximately 10% in Shizuoka, and slightly less than 20% in Mie.

5. Kansai area

   In Osaka, the number of new cases of infection is approximately 114, with a ratio of this week to last week of less than 1 (0.71). The infected individuals are mainly in their 30s or younger. It decreased in all age groups. The use rate of beds and the use rate of beds for severe cases are both slightly more than 10%. In Shiga, Kyoto, Hyogo, Nara, and Wakayama, the numbers of new cases of infection are approximately 81, 96, 93, 77, and 69, respectively, with a ratio of this week to last week of less than 1 (0.56, 0.58, 0.68, 0.72, and 0.69). The use rates of beds are slightly more than 10% in Shiga, Kyoto, Hyogo, and Wakayama, and less than 10% in Nara.

6. Kyushu

   In Fukuoka, the number of new cases of infection is approximately 124, with a ratio of this week to last week of less than 1 (0.65). The individuals are mainly in their 20s or younger. It has slightly decreased or decreased in all age groups. The use rate of beds is slightly more than 10%. In Saga, Nagasaki, Kumamoto, Oita, Miyazaki, and Kagoshima, the numbers of new cases of infection are about 97, 152, 140, 110, 153, and 171, respectively, with a ratio to this week to last week of less than 1 (0.65, 0.91, 0.77, 0.65, 0.71, and 0.83). The use rates of beds are approximately 10% in Saga, slightly more than 10% in Nagasaki, slightly more than 20% in Kumamoto, slightly less than 20% in Oita and Miyazaki, and slightly less than 30% in Kagoshima.

7. Okinawa

   The number of new cases of infection is the highest nationwide, at approximately 590, 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. It decreased in all age groups. The use rate of beds is slightly less than 40%, while the use rate of beds for severe cases is slightly more than 10%.

8. Areas other than the above

   In Aomori, Iwate, Hiroshima, and Yamaguchi, the numbers of new cases of infection are approximately 105, 88, 122, and 103, respectively. The use rate of beds is about 20% in Aomori, Hiroshima, and Yamaguchi, and slightly more than 20% in Iwate.

Future outlook and measures to be taken

• Infection status

  • The number of new infections reported continued to decrease in almost all regions nationwide. By region, the moving average for last week is lower than the peak of last summer in the Tokyo metropolitan area, Aichi, Osaka, Fukuoka and other metropolitan areas, as well as some regional cities. On the other hand, although the highest situation in Japan remains in Okinawa, it has been decreasing for about the last three weeks.

  • The number of new cases of infection by age group continued to decrease in all age groups, and a similar tendency has continued by region.

  • As the places of new cases of infection, the proportion of welfare facilities for the elderly, nursery schools, business establishments, and restaurants remains high. Recently, the proportion of schools, hospitals, and welfare facilities for people with disabilities is on the rise.

  • The number of new cases of infections showed an increasing trend after the end of Golden Week, but a decreasing trend continued thereafter. Regarding the future infection situation, short-term forecasts for metropolitan areas expect the decreasing trend to continue, but there is concern that the number of infected people will increase around the summer because (1) the immunity acquired by the third vaccination and infection will gradually decrease, (2) June is the rainy season, and the flow of people tends to be relatively restrained, but after July, due to the influence of summer vacation, an increase in contact is expected, and (3) there is a possibility that the Omicron variant will be replaced by a new strain, and it is therefore necessary to pay close attention to the impact on the medical care provision system.

• Factors that increase and suppress infection

  1. It is thought that infection status is affected by the following changes in factors that increase and suppress infection.

  1. [Contact patterns]

     The nighttime population increases or decreases each week in some regions, while in other regions the number increases continuously. Since in some areas the number exceeds the peak at the end of last year, it is necessary to pay attention to the impact on the infection status.

  2. [Epidemic strain]

     The replacement by the BA.2 lineage has largely occurred and compared to the time when the BA.1 lineage was dominant, it may be a factor in a slowdown in the decrease. In addition, the BA.2.12.1 lineage and BA.5 lineage have been detected in Japan, and it is necessary to continue monitoring.

  3. [Vaccination]

     The third vaccination is proceeding, but it should be noted that as a certain period elapses after the third vaccination, the preventive effect against infection is expected to diminish from those who received vaccination earlier. In addition, the immunity acquired from previous infections is expected to gradually decline in the future.

  4. [Climate factors]

     When the temperature rises, it becomes easier to ventilate, due to climate conditions. However, when the temperature rises or the rainy season begins, rainfall may increase indoor activities.

• Medical care provision system

  • In Okinawa, the number of inpatients, the use rate of beds, and the use rate of beds for severe cases continue to decrease. Nationwide also, with a continuing decreasing trend in the number of new cases, the use rate of beds is decreasing in almost all regions, and the number of patients in home care or who are adjusting medical treatment is decreasing in all regions.

  • In cases of difficult emergency transportation, despite regional differences in both suspected non-COVID-19 cases and suspected COVID-19 cases, the numbers are decreasing nationwide.

• 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. In addition, it is necessary to continue monitoring the trends of variants through genomic surveillance. 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 also need to inspect the medical care/testing system and the public health center system in order to strengthen the response based on the characteristics of the Omicron variant.
     • It is necessary to continue efforts to establish the required system for providing medical care based on the regional infection status.
     • When strengthening and thoroughly implementing a medical care support system for the elderly, 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, in order to efficiently carry out public health center operations and maintain the public health center functions required in the region, it is important to secure a system for outsourcing or centralization at the main office.
  3. [Provision of information to unvaccinated individuals, and those receiving the third or fourth vaccination, etc.]
     • It is important for local governments to promote the provision of information on vaccination. The third and fourth vaccinations must also be steadily implemented, along with vaccinations for unvaccinated persons. Individuals being vaccinated for the first time have also been reported to have a lower risk of prolonged symptoms. In a study on the efficacy of novel coronavirus vaccines conducted by Nagasaki University, the efficacy of completing 2-dose and 3-dose vaccinations was evaluated.
     • The main purpose of the third vaccination is prevention of onset and aggravation. As of June 7, the rate of third vaccinations was about 89% for the elderly aged 65 years and older, and about 60% overall. It is necessary to steadily implement a third vaccination in subjects, and to vaccinate as many desiring recipients as possible. A fourth vaccination was started from May 25 as a special temporary vaccination to prevent aggravation in persons aged 60 years and older, persons with underlying diseases at high risk of severe symptoms, and other persons deemed by doctors to be at a high risk of severe symptoms. On the same day, it became possible to start administration of a new vaccine for the first to third doses. This vaccine is different from the previous new coronavirus vaccine and can ensure a diversity of vaccines. It is also manufactured in Japan, ensuring the stability of vaccine supply.
     • Vaccination of children from 5 to 11 years old is being implemented as a special temporary vaccination, and it is necessary to promote vaccination, considering that the obligation to make efforts does not apply to these children. In hope of preventing infections in children, it is also important for parents and the adults around them to be vaccinated a third time.
  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 addition, while continuing pre-departure tests and responding to the risk of inflow, whole genome analysis should be continued for those who are positive in the immigration test to monitor strains circulating 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 the Omicron variant.

  • In schools, kindergartens, nursery schools, etc., infection control measures including active promotion of vaccinations for teachers and nursery teachers will be thoroughly implemented, as well as infection control measures for children, while sharing situations where the risk of infection in children and students increases with staff, children, parents, etc. It is also necessary to continue educational activities and social functions as far as possible. 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. At the same time, thorough infection control measures are also required at home. Masks are not recommended for children under 2 years of age, and for preschool children over 2 years of age, there are concerns about the risk of heat stroke and the effects of difficulty in seeing facial expressions. Therefore, it is necessary to thoroughly inform nursery schools, etc. that masks are not uniformly required, and that children should not be forced to wear them. Schools must be thoroughly informed that it is not necessary to wear a mask during physical education classes, athletic club activities, or when going to and from school.
  • It is necessary to take thorough measures at nursing care facilities, in order to control infections in the elderly. Therefore, workers are actively examined. In order to prevent aggravation, the fourth vaccination of residents will proceed. Further, 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.
  • In the workplace, in order to maintain social functions, in addition to utilizing business continuity plans, efforts are required to utilize telework and promote the taking of time off. In addition, thorough health management of employees and securing an environment where they can take a leave of absence if they are even a little unwell are necessary. In addition, a third vaccination in the workplace should be actively promoted.

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

  1. The situation is lower than the peak last summer nationwide, but it is still high in more than half of the nation's regions, especially in regional cities. For this reason, it is necessary to thoroughly implement basic infection control measures and daily health management, and cooperate in efforts to reduce the risk of infection.

  2. [Vaccination]

     It is important for people to receive a third vaccination as soon as possible, regardless of type, once such vaccination becomes available. People with the novel coronavirus disease may experience severe conditions even if they are young, and may also suffer from prolonged symptoms. Accordingly, it is necessary to promote vaccinations not only in the elderly, who have a risk of aggravation of symptoms, but also in younger persons, in order to protect their health. It is also important to consider vaccination again for people who have not received the first or second vaccination.

  3. [Thorough infection control]

     Basic preventative measures are still effective against infection with the Omicron variant. Therefore, it is necessary to 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.

  4. [When going out]

     Crowded or poorly ventilated places with a large number of people and loud voices, where the risk of infection is high, should be avoided. 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 done in a small group without speaking to the extent possible, and masks should be worn at all times except while eating and drinking. On the other hand, the use of a mask is not necessary outdoors, except when talking at a close distance. Especially in summer, removing the mask outdoors is recommended from the viewpoint of preventing heat stroke.

  5. [Health management]

     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. In particular, caution should be exercised when meeting persons who are at a high risk of severe illness, such as the elderly.

<< 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 presents 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 limited data suggest that the incidence of pneumonia is higher than that of seasonal influenza, this needs to be investigated through 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 persons have died from causes other than the novel coronavirus infection itself. In particular, some have refused highly invasive treatments, while others did not meet the definition of severe disease, due to a worsening of an underlying disease, or for 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, and 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 at 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 effects of a first vaccination against infection and disease onset are 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 infection by the Omicron variant, as well as information regarding how these vaccine effects are attenuated after a third vaccination.

6. [BA.2 lineage]

   Overseas, the number of infected patients has increased, while replacement with the BA.2 lineage is progressing. However, the number is currently decreasing worldwide. In Japan, the influx of the Omicron variant from overseas initially comprised both BA.1 and BA.1.1; however, BA.1.1 has since become dominant. Currently, it has been largely replaced by the BA.2 lineage. 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.

7. [XE, BA.4, BA.5, and BA.2.12.1 lineages]

   The XE lineage of the Omicron variant is a recombinant of the BA.1 and BA.2 lineages of the Omicron variant. The XE lineage has been detected in quarantine. The WHO report indicated that the rate of increase in community-acquired infections was approximately 10% higher than that of the BA.2 lineage. The BA.4, BA.5, and BA.2.12.1 lineages have been detected in quarantine. Of these, the BA.5 and BA.2.12.1 lineages have also been detected in Japan. According to the US CDC, the BA.2.12.1 lineage reportedly has a 25% higher rate of increase in infected individuals than the BA.2 lineage. In some countries and regions, the detection rates of the BA.4, BA.5, and BA.2.12.1 lineages have increased, and the BA.2 lineage has been replaced by these variants, suggesting its superiority in terms of an increase in the number of infected patients. The National Institute of Infectious Diseases has suggested that although there are no reports indicating large differences in infectivity or severity, information on the overseas infection status and findings regarding the characteristics of the virus should be collected and analyzed, as before, and genomic surveillance should be continued for purposes of monitoring.

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