国立感染症研究所

89th Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (June 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) was about 92 per 100,000 in the last week, increasing to a ratio of this week to last week of 1.17. The number of new cases of infection by age group slightly increased in almost all age groups.
  • With the number of new cases of infection increasing, the number of patients being treated and number of severe cases have gradually increased. The use rate of beds is generally low, and the number of deaths is on a decreasing trend.

    Effective reproduction number: On a national basis, the most recent number is below 1, at 0.98 (as of June 12). The figure stands at 1.02 in the Tokyo metropolitan area and 0.97 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 77 (roughly 85 in Sapporo City), with a ratio of numbers for this week to last week of less than 1 (0.85). The infected individuals are mainly in their 30s or younger. The number leveled off in those in their 70s, and decreased slightly or decreased in other age groups. The use rate of beds is slightly less than 10%.

  2. North Kanto

    In Ibaraki, the number of new cases of infection is approximately 52, with a ratio of this week to last week of more than 1 (1.01). The individuals are mainly in their 20s or younger. The number slightly increased in those in their teens and 20s, slightly increased in the 40s and 50s, and decreased slightly or decreased in other 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 30 and 34, respectively, with a ratio of this week to last week of less than 1 (0.85 and 0.72). The use rates of beds are slightly less than 10% in Gunma and less than 10% in Tochigi.

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

    In Tokyo, the number of new cases of infection is approximately 118, with a ratio to the previous week of more than 1 (1.37). The infected individuals are mainly in their 30s or younger. It has increased or slightly increased in all age groups. The use rate of beds is slightly more than 10%, and the use rate of beds for severe patients is slightly more than 10%. In Saitama, Chiba, and Kanagawa, the numbers of new cases of infection are approximately 65, 63, and 77, respectively, with a ratio of this week to last week of more than 1 (1.13, 1.27, and 1.25). The use rate of beds is approximately 10% in Saitama, and slightly less than 10% in Chiba and Kanagawa.

  4. Chukyo/Tokai

    In Aichi, the number of new cases of infection is approximately 88, with a ratio of this week to last week of more than 1 (1.21). The individuals are mainly in their 20s or younger. It has increased or slightly increased in all age groups. The use rate of beds is slightly less than 10%. In Gifu, Shizuoka and Mie, the ratios of this week to last week are more than 1 (1.21, 1.29, and 1.29, respectively), with the number of new cases of infection at approximately 75, 54, and 75. The use rates of beds are slightly less than 10% in Gifu, less than 10% in Shizuoka, and slightly more than 10% in Mie.

  5. Kansai area

    In Osaka, the number of new cases of infection is approximately 117, with a ratio of this week to last week of more than 1 (1.33). The individuals are mainly in their 20s or younger. The number leveled off in those in their 80s and older and increased slightly or increased in other 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 10%. In Kyoto, Hyogo and Wakayama,, the numbers of new cases of infection are 82, 86, and 77, respectively, with a ratio to that for the previous week of more than 1 (1.04, 1.21, and 1.53). In Shiga and Nara, the numbers of new cases of infection are approximately 75 and 54, with a ratio of this week to last week of less than 1 (0.98 and 0.97). The use rates of beds is slightly more than 10% in Kyoto, approximately 10% in Wakayama, slightly less than 10% in Shiga and Hyogo, and less than 10% in Nara.

  6. Kyushu

    In Fukuoka, the number of new cases of infection is approximately 110, with a ratio of this week to last week of more than 1 (1.20). The infected individuals are mainly in their 30s or younger. It has increased or slightly increased in all age groups. The use rate of beds is approximately 10%. In Saga, Nagasaki, Kumamoto, Oita, and Miyazaki, the numbers of new cases of infection are 187, 137, 227, 84, and 147, respectively, with a ratio of this week to last week of more than 1 (1.42, 1.16, 1.39, 1.34, and 1.53, respectively). In Kagoshima, the number of new cases of infection is approximately 148, with a ratio of this week to last week of less than 1 (0.99). The use rates of beds are slightly more than 10% in Saga, approximately 10% in Nagasaki, slightly more than 20% in Kumamoto, less than 10% in Oita and Miyazaki, and slightly more than 20% in Kagoshima.

  7. Okinawa

    The number of new cases of infection is the highest nationwide, at 650, with a ratio of this week to last week of more than 1 (1.15). The infected individuals are mainly in their 30s or younger. The number leveled off in those in their 60s, but increased in other age groups. In particular, the increase among those in their teens or younger is marked. The use rate of beds is approximately 40%, while the use rate of beds for severe cases is slightly less than 20%.

  8. Areas other than the above

    In Aomori, Shimane, Hiroshima, Yamaguchi, Ehime, and Kochi, the numbers of new cases of infection are approximately 129, 195, 82, 80, 107, and 111, respectively. The use rates of beds are slightly more than 20% in Aomori, and slightly more than 10% in Shimane, Hiroshima, Yamaguchi, Ehime, and Kochi.

Future outlook and measures to be taken

  • Infection status
    • The number of newly infected individuals has turned upward nationwide (29 prefectures have a ratio to the previous week exceeding 1). By region, although still decreasing in some regions (decreased in 18 prefectures), the level generally showed an increasing trend in large cities. In some areas, the rate of increase is high. Okinawa has a higher level of infection than other regions and is on an upward trend, so it is necessary to pay particular attention to future trends in infection status.

    • The number of new cases of infection by age group slightly increased in almost all age groups nationwide. In addition, the increase in those in their 20s is large in Tokyo. In Okinawa, the number is increasing in all age groups, but as it is increasing even in the elderly, it is necessary to pay close attention to the infection situation.

    • The proportion of new cases of infection at schools continues to decrease, but the proportion remains high. In addition, the proportion at home is decreasing.

    • Regarding the future infection situation, the number of new cases of infection is expected to increase in large cities; (1) the immunity acquired by the third vaccination and infection will gradually decrease, (2) an increase in contact is expected after July due to the influence of after the rainy season, three consecutive holidays and summer vacation, and (3) since there is a possibility that the Omicron variant will be replaced by a new lineage, it will be 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 is showing an increasing trend in many regions, mainly in large cites. Since in some areas the number approaches or exceeds the peak at the end of last year, it is necessary to pay attention to the impact on the infection status.

    2. [Epidemic strains]

      The BA.1 lineage has been replaced by the BA.2 lineage, but the new lineages BA.2.12.1, BA.4, and BA.5 lineages have been detected in Japan. In particular, the BA.5 lineage may become the mainstream lineage in Japan in the future, and could be a factor in increasing the number of infected people.

    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. [Climatic factors]

      It is a time when indoor activities increase due to rising temperatures, but ventilation may be difficult because air conditioning is prioritized.

  • Medical care provision system
    • Nationwide, the use rate of beds is generally low, but as the number of newly infected individuals begins to rise, it has stopped decreasing in large cities. In Okinawa, the number of inpatients and the use rate of beds has leveled off or slightly increased, and the use rate of beds for severe cases is also increasing.

    • In cases of difficult emergency transportation, recently there is an increasing trend nationwide for both suspected non-COVID-19 cases and suspected COVID-19 cases. In addition, it is expected that the number of emergency transports due to heat stroke will increase, so careful attention should be paid.

  • 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, and other applicable cases, confirmation via PCR testing for mutant strains and a whole-genome analysis is required.

    2. [Efforts by local governments]
      1. The number of new cases of infection is on the rise nationwide, and it is necessary for local governments to inspect the medical care/testing system and public health center system.

      • It is necessary to re-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.
      • Recently, effective and less burdensome measures against infection in medical and nursing care settings have been seen, and while knowledge about the risk of infection and infection control has accumulated, it is important to consider reasonable measures against infection according to the actual conditions at each facility.
    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. The main purpose of the third vaccination is prevention of onset and aggravation. As of June 29, the rate of third vaccinations was about 90% for the elderly aged 65 years and older, and about 62% 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 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. It also 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. Nationwide, the number of new cases of infection has started to increase. The number of contacts is expected to increase due to the three consecutive holidays and summer vacation. For this reason, in order to minimize the increase in the number of cases of infection, 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]

      In preparation for the spread of infection, a fourth vaccination is recommended for the elderly and those at risk of severe illness. It is important for people to receive the third vaccination, regardless of type. 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, but also in younger persons, in order to protect their health. It is important to consider vaccination again for people who have not received the first or second vaccination.

    3. [Thorough infection control]

      As basic infection control measures, 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. It is also suggested that the incidence of pneumonia is higher than that of seasonal influenza, but given the limited data, 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. It has been reported that there are many cases in which the new coronavirus infection is not the direct cause of death, for example, people who have been in a facility for the elderly before the infection are infected and die due to the worsening of the underlying disease. Attention should also be paid to worsening of the condition of elderly infected people and infected people with an underlying disease, and to the onset of heart failure and aspiration 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. [Sublineage of Omicron variant]

    Currently, the BA.2 lineage remains the mainstream in Japan. Worldwide, the proportions of the BA.4 and BA.5 lineage are increasing, suggesting that these lineages are superior to the BA.2 lineage in terms of increasing the number of infected people. The number of positive tests is on the rise globally, as replacement by the BA.4 and BA.5 lineages proceeds. However, there are no clear findings on the infectivity of the BA.4 and BA.5 lineages.

    According to the WHO report, the findings accumulated from multiple countries indicate that there is no increase in the severity of the BA.4 and BA.5 lineages compared to existing Omicron variants.

    The BA.4 lineage and BA.5 lineage have both been detected in Japan and in quarantine. According to genomic surveillance, the BA.2 lineage continues to be the mainstream in Japan, but the detection rates of the BA.4 and BA.5 lineages may increase in the future. It is necessary to continue to collect and analyze the situation and findings in other countries regarding the characteristics of the virus, and to continue monitoring by genome surveillance.

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

 

Copyright 1998 National Institute of Infectious Diseases, Japan

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