国立感染症研究所

40th meeting of the COVID-19 advisory board of Ministry of Health, Labour and Welfare (June 23, 2021).  Material 1

 

Evaluation of the latest infection status, etc.

Infection status

  • The number of new cases of infection nationwide has been declining with approximately 8 per 100,000 population for the latest week of reporting dates. There is generally a downward trend in regions where the infection spread.
  • Along with the decrease in the number of new cases of infection, the numbers of severe patients and deaths have decreased. In addition, the proportion of elderly patients among infected patients tends to decrease. However, there are regions where the decreasing speed has slowed due to an increasing trend in the flow of people, and there is concern about a possible future rebound in these regions. In particular, in Tokyo and the metropolitan area, the number of new cases of infection stopped decreasing and is remaining flat, and therefore it is necessary to take thorough measures to prevent a rebound.  

    The nationwide effective reproduction number has been below 1 at 0.80 (as of June 6).

Analysis of infection status [local trends]

*The value of new cases of infection is the total number for the latest week of reporting dates per 100,000 population.

  1. Okinawa

    The number of new cases of infection remains high at approximately 40, but continues to decrease. New cases are mainly in those in their 20s to 30s. The use rate of beds remains high, and the hospitalization rate has been increasing as the number of patients receiving home care and those arranging hospitalization are decreasing in association with the decrease in the number of new cases of infection. The number of new cases of infection is expected to decrease in future, but both nighttime and daytime populations started to increase after new cases of infection turned downward. Attention should be paid to whether the upward trend in the de facto population continues.

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

    In Tokyo and Chiba, the number of new cases of infection has leveled off and has started to increase to approximately 20 and 12, respectively. In Tokyo, new cases are mainly in those in their 20s and the number of infected patients is high in the urban central area. In Saitama and Kanagawa, the number of new cases of infection has been on a downward trend to approximately 7 and 14, respectively. In Tokyo, the nighttime population continued to increase but has started to decline slightly since last week. We need to pay close attention to future movements. In Chiba and Kanagawa, the nighttime population has slightly decreased from staying flat. The nighttime population in Saitama has increased. There is concern that it is becoming difficult to obtain cooperation with the measures. Particularly in Tokyo, if the upward trend in the de facto population continues, there is strong concern about a rebound and caution is therefore required.

  3. Kansai Area

    In Osaka, Hyogo, and Kyoto, the number of new cases of infection has been decreasing to approximately 7, 3, and 4, respectively. As the number of new cases of infection has been decreasing, there has been some improvement, such as a decrease in the number of inpatients and severe patients, but clusters in facilities for the elderly are continuing. In Osaka, the nighttime and daytime populations continue to increase and have returned to the level at the start of the third declaration of a state of emergency. In Hyogo, the nighttime population remains at a level lower than the minimum value during the second declaration of a state of emergency. In Kyoto, it has increased again in the latest week. The number of new cases of infection is expected to decrease, but careful monitoring is necessary, also of the de facto population.

  4. Aichi

    The number of new cases of infection has continued to decrease to approximately 8. As the number of new cases of infection has decreased, the numbers of inpatients and severe patients have also decreased, and the use rate of beds both for inpatients and for severe patients is decreasing. The nighttime population remains at a low level. Although the number of new cases of infection may decrease in future, attention should be paid as to whether these trends will continue.

  5. Hokkaido

    The number of new cases of infection has continued to decrease to approximately 8. In Sapporo City, the center of infection spread, the number has decreased to approximately 15. The number of new cases of infection is expected to decrease in future. However, the nighttime population, which had continued to decrease, started to increase and then stayed flat for the latest week. Attention should be paid to whether the decreasing trend in the number of new cases of infection continues. The use rate of beds has remained high in Sapporo City.

  6. Fukuoka

    The number of new cases of infection has continued to decrease to approximately 5. As the number of new cases of infection has decreased, the numbers of inpatients and severe patients have also decreased, and the use rate of beds both for inpatients and for severe patients is decreasing. The nighttime population remains at a low level. The number of new cases of infection is expected to decrease in future, but it is necessary to carefully monitor whether these trends will continue.

  7. Other than the above

    In Yamanashi, the number of new cases of infection is approximately 19. The number increases due to the occurrence of clusters and it should be watched carefully.

Analysis of mutant strains

  • Clusters due to the B.1.617.2 lineage variant (delta variant) have been reported. In some regions, the percentage of screening tests (mechanical estimation) is several tens of percents because of the effects of clusters, but approximately 3% nationwide. However, it is indicated that the delta variant will continue to replace the existing strains, and therefore it is necessary to pay close attention to it. In addition, the delta variant is suggested to be more infectious than the B.1.1.7 lineage variant (alpha variant). Study results showing vaccine efficacy against variants after the second vaccination have also been reported. It is necessary to continue analysis.

Future outlook and measures to be taken

  • Emergency measures and priority measures, such as for prevention of the spread of disease (priority measures) have been lifted and eased in many regions since June 21. This is attributed to the steady results of these measures, including the decrease in the number of new cases of infection and the reduction in the burden on the medical care provision systems owing to the cooperation of citizens and business operators. Cooperation of people is still essential to avoid a rapid rebound in future.
  • The downward trend in the number of new cases of infection may continue nationwide in the future, but there is strong concern about a possible rebound, given the experiences where the flow of people increased and rebounded immediately after the measures were lifted as well as the possibility that infection will spread faster than before due to alpha and delta variants. Particularly in Tokyo, which has great impact across the country, a future rebound is strongly concerned in case the flow of people and people gathering cannot be restricted by thorough implementation of priority measures.
  • Vaccinations have mainly been performed in elderly people and are expected to prevent serious disease. However, the existing strains may continue to be replaced by the delta variant. If the number of infected patients continues to surge after a rebound, the number of severe patients may increase and the medical care provision systems will be overwhelmed.
  • According to the recently compiled “Measures after June 21, 2021,” vaccination is needed to be steadily promoted including workplace vaccination and necessary efforts should be continued to curb the spread of infection. Based on the current situation of infection, prompt actions including tightening of measures are essential. Each local government should conduct necessary measures in a timely manner if there is any sign of the spread of infection.
  • Concerning the delta variant, which is concerned about replacement with the existing strains, it is particularly essential to suppress the spread of infection as much as possible by following the measures: strengthening of nationwide monitoring by screening of the L452R variant that aimed to cover 40% of all positive patients, as well as active epidemiological surveys and thorough tests for variants. It is also necessary to continue taking prompt border control measures.
  • In addition, in the course of promoting vaccination, it is necessary to consider future measures along with the appropriate evaluation of the impact on the situation of infection, changes in the number of inpatients, the rate of hospitalization, and the number of severe cases, as well as the associated burden on the medical care provision systems.

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

Copyright 1998 National Institute of Infectious Diseases, Japan

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