国立感染症研究所

26th meeting of the COVID-19 advisory board of Ministry of Health, Labour and Welfare (March 3, 2021).  Material 1

 

Evaluation of the latest infection status, etc.

Infection status

  • The number of new cases of infections in Japan has continued to decrease since the middle of January based on the reporting date (from the beginning of January based on the date of onset), and has become approximately 5 per 100,000 people over the last week. The decreasing speed has slowed down since the middle of February, and the possibility of bottoming out and recurrences should be carefully monitored.

    Effective reproduction number:The effective reproduction number has fallen below 1 from the beginning of January nationwide and has been 0.84 recently (as of February 14). In Tokyo and its 3 neighboring prefectures, Osaka/Hyogo/Kyoto, Aichi/Gifu, and Fukuoka, the levels remain below 1. (as of February 15)

  • The decreasing trend in the numbers of inpatients, severe patients, deaths, and patients receiving treatment is continuing. In contrast, the proportion of new patients aged 60 years or older has exceeded 30%, and decreases in the number of severe patients and deaths seems to take more time than the decreases in the number of new cases of infections and inpatients.
[Local trends]

* The value of new cases of infections is the number of people per 100,000 in the total number for the latest week on the basis of reporting dates

  1. (1) Metropolitan area:
    In Tokyo, the decreasing trend in the number of new cases of infections is continuing and has reached approximately 13, which is lower than the index for stage III, 15. In Kanagawa, Saitama, and Chiba, the decreasing trend in the number of new cases of infections is continuing, i.e., approximately 8, 9, and 14, respectively. A decreasing trend has been observed throughout Tokyo and its 3 neighboring prefectures. However, the speed of decreasing infections has slowed down, and the number of new infections remains at the level close to 15 in Tokyo and Chiba. With decreases in the numbers of new cases of infections and patients receiving treatment, adjustments for hospitalization, etc. by local governments have improved and the burden has been reduced, for example, the figures below the index of Stage IV. However, the medical care provision systems are under severe pressure, such as high use rate of beds.
  2. (2) Kansai Area:
    The decrease in the number of new cases of infections has continued, and the number of new cases of infections has dipped below 5, excluding Osaka. Although the medical care provision systems are still under severe pressure in all areas, the burden has been reduced with decreases in the numbers of new cases of infections and patients receiving treatment. On the other hand, clusters in facilities for the elderly have continued in Osaka, etc. Attention should be paid to increases in the burden associated with hospitalization of elderly persons.
  3. (3) Areas other than those listed above:
    The number of new cases of infections is generally continuing to decrease. On the other hand, caution is required as clusters have occurred in some regions.
[Mutant strain]
  • For the mutant strains detected in the UK and South Africa, etc. whose effects become a concern, the risk of more rapid spread is high. Cases of infection with mutant strains have been continuously detected in Japan. Possibly because of active epidemiological investigations by local governments, an increasing trend of infections and cluster reports has been observed.

Analysis of infection status

  • In the 4 prefectures under the state of emergency measures, the effective reproduction number is around 0.9 and the decreasing trend in the number of new cases of infections is continuing, however the decreasing speed has slowed down. There are many cases with unknown source of infection and place of cluster occurrence in the Tokyo metropolitan area, and a tendency of re-increase in people coming and going during nighttime is observed. It is important to prevent recurrences and maintain the decreasing trend.
  • Clusters have continued to occur in facilities for the elderly, and also at restaurants in some regions. Furthermore, there is a trend of bottoming out in the number of infections in young people and clusters in regions where the infections had decreased, and therefore attention should be paid to such situations.
  • The decrease in the number of new cases of infections has been delayed in urban areas compared to surrounding areas. Efforts to maintain the decreasing trend are needed in the presence of the risk of mutant strains. A trend of increasing patients with mutant strains is observed even under the Declaration of a State of Emergency, and an increase in the opportunities of social contacts or relaxing the measures against infection may cause a shift in the prevalent strains from the existing ones. There is a concern about the spread of the risk than before.

Measures to be taken

  • It is important to reduce the burden on medical care provision systems, secure a system for stable vaccination, and reduce risks of the spread of mutant strains, etc. by continuing to reduce the number of new cases of infections. In this context, concern about recurrences induced by lifting the Declaration of a State of Emergency should be noted. Especially in the Tokyo metropolitan area, the number of infections is higher than in the other areas, and the continued infection has a great influence on the other areas. It is necessary to maintain the number of infections as low as possible to prevent re-spread of infection. In order to achieve this, efforts required to further reduce infections such as measures based on the information and assessments from active epidemiological investigations should be made in view of local situations of infection. Similar efforts are required also in regions where the state of emergency measures have been lifted.
  • It is necessary for the national and local governments to send out consistent messages about the need for cooperation in the efforts to reduce infections.
  • To reduce the risk of infection when eating and drinking out, it is important to publicize how the users of restaurants should behave in these situations, as well as the efforts of business operators.
  • It is also necessary to send out effective messages so that people will refrain from parties and trips related to annual events from the end to the beginning of fiscal year (graduation ceremonies, welcome and farewell parties, and cherry-blossom viewing).
  • It is important to take measures in case of another wave of infection as well as to prevent re-spread. Specifically, such efforts as the following are required: (1) steady promotion of vaccination; (2) strengthening measures against mutant strains; (3) early detection using active implementation of the test according to the risk of infection and re-strengthening active epidemiological investigations, promotion of the preventive measures against infection, such as continuation of measures for restaurants and facilities for the elderly; and (4) enhancement of medical care provision systems to flexibly provide medical care for the novel coronavirus infection.
[Mutant strain]
  • Considering that the effects of mutant strains will become larger, measures to minimize the effects are required. To realize this, the following measures are required according to the package of the measures against mutant strains presented some days before: (1) continuation of strengthening the border control measures, (2) prompt reinforcement of the surveillance system of mutant strains in Japan (with cooperation with private testing organizations and universities. The national government will regularly confirm the number of tests conducted by local governments), (3) early detection of persons infected with mutant strains, identification of close contacts and the source of infection through active epidemiological investigations and prompt implementation of preventive measures against infection, (4) assessment and analysis of the epidemiological information on the infectivity and pathogenicity of mutant strains (continuing to understand the present situation of variants with mutations such as E484K other than N501Y variants) and proper dissemination of information, and (5) promotion of centralized collection of samples and clinical information/research development such as analyses.

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

Copyright 1998 National Institute of Infectious Diseases, Japan

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