国立感染症研究所

32th meeting of the COVID-19 advisory board of Ministry of Health, Labour and Welfare (April 27, 2021).  Material 1

 

Evaluation of the latest infection status, etc.

Infection status

  • The number of new cases of infection nationwide has continued to increase based on the reporting date despite a tendency of decrease in the ratio of this week to last week, and the number in the most recent week is approximately 27 per 100,000 population. In addition to the Kansai Area, Tokyo Metropolitan Area, and Chukyo Area, the number of persons with infection is increasing in many local areas. With the increase in the number of new cases of infection, the number of severe patients has rapidly increased, and the number of deaths also started to increase. Spread of infection to the elderly may further increase the number of severe patients.

    The effective reproduction number exceeded 1 in late February and has recently become 1.10 (as of April 10). The level remains below 1 in Miyagi and Okinawa, but above 1 in Tokyo and its 3 neighboring prefectures, as well as Aichi, Osaka and Hyogo as of April 11.

  • The proportion of mutant strains as variants of concern (VOC) remains high, around 80%, in the Kansai area (Osaka, Kyoto, and Hyogo); such strains seem to have been replaced with the existing ones in the recent spread of infection. The proportion has been increasing to about 40% in Tokyo and about 60% in Aichi, and also in other regions. It is expected that the predominant strains will change all over Japan. No obvious trend of infection spread has been seen in persons aged less than 15 years. The number of pediatric patients is not remarkably high in the recent spread of infection.
  • In Osaka, it has been pointed out that the rate of severe cases has become high in patients aged 40 years or older, but there is a possibility of increase in the proportion of mutant strains or mild cases no longer diagnosed, and therefore it is necessary to continuously monitor the situation.
Analysis of infection status [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) Kansai area: Especially in Osaka, Hyogo and Nara, the medical care provision systems and the public health systems are under very severe pressure. Emergency transportation will become more difficult in many cases, making the need for restrictions on general medical care inevitable. To protect the system to provide necessary medical care, it is essential to reduce the number of new cases of infection.
    In Osaka, Hyogo, Kyoto and Nara, the number of new cases of infection is high in all age groups, predominately 20s and 30s. Three weeks have passed since the start of priority measures, such as for prevention of the spread of disease in Osaka, and the emergency measures were adopted again on April 25. The daytime and nighttime population downtown decreased, close to that under the previous Declaration of State of Emergency. The ratio of this week to last week is still decreasing. Although the number of new cases of infection remains at a very high level, about 88. The numbers of inpatients and severe patients are expected to increase further (the proportion of severe patients in their 40s and 50s also increased). In the surrounding prefectures, the number of new cases of infection is increasing in general, i.e., about 64, 38, 49, 26 and 23 in Hyogo, Kyoto, Nara, Wakayama and Shiga, respectively (in Shiga, the ratio of this week to last week has continued to be 1 or more for 2 weeks or longer).
    In Osaka, the infection route is unknown in more than 60% of cases and infections in such places as households, workplaces, and settings of club/group activities, as well as elderly facilities, have been observed.
  2. (2) Metropolitan area (Tokyo and 3 prefectures): Two weeks have passed since the start of priority measures, such as for prevention of the spread of disease in Tokyo, and the emergency measures were adopted again on April 25. The nighttime population began to decrease but seems to have bottomed out recently, and it is not lower than that under the previous Declaration of State of Emergency. With the spread of infection in persons in their 20s to 50s, the number of cases of infection is increasing as a whole, to be about 37. The ratio of this week to last week has been 1 or higher for a month or longer. The infection is spreading from the center of Tokyo to its surrounding areas. It is necessary to watch carefully whether infection will decrease.
    In Tokyo, infection is spreading at restaurants, in addition to cases of infection in facilities, settings of club/group activities, and workplaces. The number of persons receiving medical care at accommodations or at home, and cases in the process of arranging hospitalization has started to increase, and there is concern about an increase in the burden on the medical care provision systems in future.
    In Saitama, Chiba and Kanagawa, the ratio of this week to last week decreased, but the number of new cases of infection is rising. The number of cases of infection is expected to increase until the measures for prevention of the spread of disease begin to show their effect.
  3. (3) Chukyo area: In Aichi, the number of new cases of infection has reached about 24, resulting from increases in almost all generations in their 60s or younger, mainly in persons in their 20s and 30s. In Nagoya City, the figure has increased in persons in all age groups, mainly in their 30s to 50s, and infection has been seen in elderly facilities, settings of club/group activities, workplaces, and communities of foreigners.
    In Mie and Gifu, the number of cases of infection increased to about 21 and 14, respectively. The ratio of this week to last week has been 1 or higher for 2 weeks or longer.
    In Aichi, the proportion of mutant strains (VOC) is about 60%, and sporadic cases and clusters caused by mutant strains have occurred frequently. Although the nighttime population began to decrease, there is still concern about continued spread of infection.
  4. (4) Other areas under priority measures, such as for prevention of the spread of disease (Miyagi, Okinawa): In Miyagi, the decreasing trend in the number of new cases of infection is continuing with a current figure of about 13. The flow of people until 20:00 is showing an increasing trend and this should be watched carefully.
    In Okinawa, the number of new cases of infection began to decrease in mid-April, but is still high, about 44. The number of patients in their 20s and 30s is decreasing, the patients in their 70s increased, and the number of inpatients is increasing.
  5. (5) Areas other than those listed above: In Fukuoka, the nighttime population began to decrease, but the number of new cases of infection has rapidly increased, primarily in persons in their 20s and 30s, since mid-April, reaching about 34. The ratio of this week to last week is above 2. The numbers of cases of infection have rapidly increased since mid- to late April in Saga, Nagasaki, Kumamoto and Oita, to about 22, 14, 16 and 26, respectively (the ratio of this week to last week has been 1 or higher for 2 weeks or longer in Fukuoka, Saga, Kumamoto and Oita). There is concern about the continued or rapid spread of infection throughout Kyushu.
    In other regions, the number of infections has surged, or has continuously increased due to clusters, etc. The number of new cases of infection is increasing or remains high, i.e., above 10, in Hokkaido, Aomori, Fukushima, Ibaraki, Gunma, Niigata, Toyama, Ishikawa, Fukui, Okayama, Yamaguchi, Tokushima, Kagawa and Ehime. Especially in Hokkaido, Ibaraki, Ishikawa, Fukui, Okayama, Tokushima and Ehime, the numbers of new cases of infection are at high levels, i.e., 18, 15, 17, 15, 21, 34 and 18, respectively (the ratio of this week to last week has been 1 or higher for 2 weeks or longer in Hokkaido, Ibaraki, Ishikawa, Okayama and Tokushima).

Measures to be taken

  • A Declaration of a State of Emergency was announced. Expansion of infection must be reduced during the Golden Week holidays with the actions based on the Declaration, and infection should be suppressed by taking this opportunity. To achieve this, people must steadily follow through with the recommendations under the emergency measures and discuss future measures in line with the effects achieved in the areas designated to be under the measures for the emergency state (Tokyo, Osaka, Kyoto and Hyogo) and the areas designated to be under priority measures, such as for prevention of the spread of disease (Miyagi, Saitama, Chiba, Kanagawa, Aichi, Ehime, and Okinawa).
  • In other regions where the number of cases of infection is increasing, it is necessary to promptly make efforts to control the infection while carefully monitoring the infection status in each area. Based on such measures, it is required to secure medical care provision systems and public health systems to respond to further spread of infection, as well as to provide necessary support by the national government.
  • There is a nationwide trend of infection spread in working generations who are active in their lifestyles, mainly in their 20s and 30s. Moreover, clusters have diversified not only in restaurants but also in other scenes of infection including workplaces and settings of club/group activities. To control infections under such circumstances, it is necessary to take thorough measures at places where clusters are likely to occur, and to take measures to largely reduce the opportunities of contact by steadily suppressing the flow of people and movement across prefectures as the Golden Week holidays approach, especially in the areas under the emergency measures or under priority measures, such as for prevention of the spread of disease.
  • Cases of infection in workplaces have become more prominent, occurring more frequently than before. It is necessary to organize systems of medical care in which workers, including non-regular employees, can feel safe enough to visit a hospital and undergo a test when they have any symptom of the disease, and reinforce the countermeasures such as teleworking and limitation on commuting.
  • In addition, clusters have frequently occurred in medical facilities and welfare facilities with the increase in infected patients. It is also important to prevent infection among facility personnel. A system for prompt testing, even in persons with mild symptoms, should be organized in addition to thorough implementation of preventive measures against infection and quick responses to the occurrence of infection, as well as periodic testing for personnel. Clusters have also occurred in communities of foreigners, requiring swift responsive action.
  • It is necessary to urge patients with symptoms to undergo the test followed by rapid conduct of the test. It is also necessary to organize a system for consultation and rapid testing during the Golden Week holidays. Furthermore, the importance of basic infection prevention, such as wearing a mask, should be reiterated.
  • Timely and prompt action is required based on evaluations/analyses of epidemiological information on the regional status of infection, infectivity, and pathogenicity while the existing strains have been replaced with mutant strains (VOC) as the predominant source of infection. It is necessary to grasp the actual state of new mutant strains using virus genome surveillance and take appropriate actions based on evaluations and analyses.

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

Copyright 1998 National Institute of Infectious Diseases, Japan

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