Current Situation of Infection, May 12, 2021

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34th meeting of the COVID-19 advisory board of Ministry of Health, Labour and Welfare (May 12, 2021).  Material 1

 

Evaluation of the latest infection status, etc.

Infection status

  • The number of new cases of infection nationwide has remained at the same level since the increase stopped based on the reporting date, and the number in the most recent week is approximately 31 per 100,000 population. The number based on the date of onset has also stopped increasing. Rather than the situation of nationwide infection spread, there are large regional differences, showing various trend as the number of infected patients surges in some areas and the number tends to decrease from steady-state situation in other areas. The number of severe cases and deaths continues to increase and is likely to further increase.

    The nationwide effective reproduction number is on a downward trend and has recently become 0.99 (as of April 25).

  • In the days ahead, the effect of the declaration of the state of emergency and the influence of the Golden Week holiday (GW) will be observed as an increase or decrease in the number of new cases of infection. However, it should also be noted that the number of reports after GW has increased due to the decrease in diagnosis and examinations and delayed reporting during GW.
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. The effective reproduction number represents the mean value of the most recent week (as of April 25)

  1. (1) Kansai area
    • Mainly in Osaka and Hyogo, the medical care provision systems and the public health systems are under very severe pressure. Emergency transportation has continued to be more difficult in many cases, and it is still in such a critical situation that general medical care will be inevitably restricted. It has also become difficult to rapidly respond to worsened symptoms in patients recovering at home and receiving care at accommodation facilities. It is essential to keep a downward trend in the number of new cases of infection to protect the system for necessary and timely care.
    • In Osaka, Hyogo, Kyoto, and Nara, the number of new cases of infection is high in all age groups, especially those in their 20s and 30s.　In Osaka, 5 weeks have passed since the start of implementation of the priority measures, such as for prevention of the spread of disease (hereinafter referred to as “priority measures”), and 2 weeks since the start of the emergency measures. The ratio of this week to last week has been 1 or lower for the most recent week and the number of new cases of infection has decreased, but remains extremely high at approximately 68.
    • In Osaka, the nighttime and daytime populations decreased rapidly to the minimum level at the time of the first declaration of the state of emergency, and then have stopped decreasing. The effective reproduction number in Osaka, Hyogo, and Kyoto is 0.88, 0.94, and 0.91, respectively. While the number of new cases of infection is expected to decrease in future, it is necessary to carefully monitor whether the decrease continues.
    • In Hyogo, Kyoto, Nara, and Wakayama, the number of new cases of infection is approximately 49, 33, 42, and 14, respectively, which, except for Wakayama, is still high but showing a downward trend. In Shiga, the number has increased again to a high level of approximately 25.
    • Local governments around the Kansai area also need to pay close attention to trends in the number of cases of infection.
  2. (2) Metropolitan area (Tokyo and its 3 neighboring prefectures)　
    • In Tokyo, 1 month and 2 weeks has passed since the start of the priority measures and the start of the emergency measures, respectively. In Saitama, Chiba, and Kanagawa, 3 weeks have passed since the start of the priority measures. In Tokyo and Saitama, it cannot be judged that the number of new cases of infection has stopped increasing. In Chiba and Kanagawa, the number has remained at the same level since the increase stopped. The number of new cases of infection in Tokyo, Saitama, Chiba, and Kanagawa is approximately 41, 21, 15, and 19, respectively. Many people are in their 20s to 50s. The ratio of this week to last week is on a downward trend at approximately 1 or lower after GW. The effective reproduction number is 1.10, 1.01, 1.09 and 1.02, respectively, and there is a possibility that a slight increase may continue at the same level.
    • In Tokyo, the spread of infection has continued mainly in central Tokyo and the neighboring areas. The nighttime and daytime populations continue to decrease, reaching a 25% lower level than the minimum value during the second declaration of the state of emergency. Although the downward trend has recently stopped, the number has not significantly increased.
    • In Saitama, Chiba, and Kanagawa, both the nighttime and daytime populations reached the minimum value during the second declaration, but the downward trend has stopped from late GW to after GW. In Chiba and Kanagawa, the daytime population has increased.
    • It is necessary to pay close attention to the future trend in the flow of people in the Tokyo metropolitan area and the impact of the decrease in the flow of people on the number of new cases of infection.
  3. (3) Chukyo area
    • In Aichi, 3 weeks have passed since the start of the priority measures while the emergency measures have been implemented as of today. The number of new cases of infection continues to increase, reaching approximately 40. The ratio of this week to last week has remained 1 or higher for 7 weeks from late March. The cases of infection are mainly of those in their 20s to 30s, but the number of new cases of infection tends to increase in almost all generations. The burden on medical institutions and public health centers is increasing and the medical care provision systems are under severe pressure. In Nagoya City, various clusters occurred in places such as restaurants, medical institutions, nursing facilities, schools, sports facilities, department stores, and community of foreigners.
    • The nighttime population continues to decrease to below the minimum level during the second declaration of the state of emergency. In contrast, the daytime population has increased from the latter half of GW. The effective reproduction number has remained 1 or higher, and the number of new cases of infection may continue to increase.
    • The priority measures were applied to Gifu and Mie from May 9, but the number of new cases of infection has surged in Gifu, reaching approximately 38. The number based on the date of onset also continues to increase. The ratio of this week to last week has remained 1 or higher for approximately 5 weeks from early April. The increase may continue in the days ahead. In Mie, the number of new cases of infection has been decreasing since the end of April. The ratio of this week to last week has been 1 or lower since May, and the number of new cases of infection has decreased to approximately 16.
  4. (4) Kyushu
    • In Fukuoka, the emergency measures began today. The number of new cases of infection has been rapidly increasing since mid-April mainly in people in their 20s to 30s, reaching approximately 57. The ratio of this week to last week has remained 1 or higher for 5 weeks from early April. The number of severe cases also considerably increased. The occupancy rate of beds is rapidly increasing and the burden on the medical care provision systems is increasing.
    • Although both the nighttime and daytime populations have decreased, they still have not reached the minimum level during the second declaration of the state of emergency. The effective reproduction number remains 1 or higher. Rapid increase in the number of new cases of infection may continue.
    • In each prefecture in Kyushu, the number of new cases of infection has also considerably increased and infection has spread throughout Kyushu. In particular, in Saga, Nagasaki, Kumamoto, Oita, and Miyazaki, the number of new cases of infection has been at a high level of approximately 42, 25, 34, 42, and 30, respectively. In Kagoshima, the number remains at the same level of approximately 21. In Nagasaki, Miyazaki, and Kagoshima, the ratio of this week to last week has been 1 or higher for 2 weeks, respectively. The effective reproduction number in the total of prefectures except Fukuoka is 1.00, but the number may continue to increase in consideration of the changes in the number of infected cases based on the reporting date.
  5. (5) Other areas under the priority measures, such as for prevention of the spread of disease (Hokkaido, Okinawa, and Ehime)
    • In Hokkaido, the priority measures were applied from May 9, but the number of new cases of infection continues to increase primarily in young people in Sapporo city, reaching a high level of approximately 47. The number of infected patients based on the date of onset may continue to increase. The number in Sapporo city is at a higher level of approximately 86 and infection has spread from Sapporo to various places in Hokkaido since the end of GW. The ratio of this week to last week has remained 1 or higher for approximately 5 weeks from early April. The effective reproduction number is high at 1.30. In addition, the medical care provision systems in Sapporo have been under severe pressure, and there have been cases of wide-area medical evacuation that were transported outside the city. Due to the influence of flow of people and meetings associated with GW, the infected cases reported from areas other than Sapporo are also increasing, and the spread of infection may occur in future. Further efforts are required to reduce the infection level in Hokkaido as a whole.
    • In Okinawa, one month has passed since the start of the priority measures. The number of new cases of infection was on a downward trend from mid-April, but is increasing again at a high level of approximately 38. Cases of infection are predominately those in their 20s to 30s. In the face of a serious shortage of beds, there is concern about an increase in the number of inpatients. Attention should be paid to the influence of movement of tourists associated with GW in the days ahead.
    • In Ehime, 2 weeks have passed since the start of implementation of the priority measures. The number of new cases of infection has decreased since late April, reaching approximately 10.
  6. (6) Areas other than those listed above
    • In other regions, the number of cases of infection has surged or continuously increased.
    • Particularly in Okayama and Hiroshima, the number of new cases of infection is very high at approximately 50 and 36, respectively. The ratio of this week to last week has remained 1 or higher for 6 weeks in Okayama and 4 weeks in Hiroshima, which is similar to the increase in the Kansai area and Aichi. The effective reproduction number is also high at 1.27 and 1.48, respectively, and there is a possibility that the spread of infection will continue in future. The population is relatively large and there is concern about the influence on the surrounding areas. Special efforts are required to reduce the infection level.
    • The number of new cases of infection exceeds 15 in Fukushima, Gunma, Ishikawa, Yamaguchi, and Kagawa. Particularly in Gunma, Ishikawa and Kagawa, the number of new cases of infection is high at approximately 28, 30, and 30, respectively. The effective reproduction number is 1.55, 1.10, and 1.68, respectively. In Gunma and Kagawa, the ratio of this week to last week has been 1 or higher for 2 weeks, and there is concern about influence on the medical care provision systems. Moreover, in Fukushima, the number of new cases of infection in the Aizu area has surged to over 50.

Analysis of mutant strains

  • The proportion of the mutant strain first detected in the UK (B1.1.7) in screening tests has exceeded approximately 70% in western Japan, suggesting that the existing strains were almost replaced by the mutant strains. Replacement of the predominant mutant strains is ongoing in other regions, e.g., approximately 60% in Tokyo and 80% in Hokkaido. In addition, analysis of screening at private testing institutions by the National Institute of Infectious Diseases demonstrates that the existing strains have been already replaced by the mutant strains in many regions.
  • No age-specific trend of infection spread has been seen. The number of pediatric patients is not remarkably high.
  • There is a finding that the risk of disease is becoming severer in persons aged 40 to 64 for B1.1.7 compared with non-N501Y mutations. Further close investigation is required to prove this.
  • In any case, it is necessary to establish medical care systems and provide treatments assuming the possibility of increased risk of disease becoming severer due to B1.1.7.

Measures to be taken

  • The declaration of the state of emergency has been extended and it is necessary to steadily suppress infection accordingly. To achieve this, people must steadily follow through with the recommendations associated with application of these measures in the areas designated to be under the emergency measures and the areas designated to be under the priority measures. In addition, the measures should be discussed in a timely manner considering the high infectivity of variants (VOC), followed by implementation.
  • Other than the above, the number of new cases of infection remains high in Okayama, Hiroshima and prefectures in Kyushu and the burden on the medical care provision systems has already been heavy in regions where the cases of infection have rapidly increased/been continuously detected. Necessary measures should be taken and strengthened immediately.
  • Furthermore, each local government is required to conduct measures promptly to establish a meeting structure to utilize advice of experts on public health and infectious diseases for countermeasures and to act from an early stage and establish a cooperative system to secure medical care provision systems based on future prospects.
  • Clusters have diversified not only in restaurants but also in other scenes of infection including workplaces, settings of club/group activities, and karaoke. Infection in the workplace is becoming noticeable, making it necessary to reduce the number of people working in the office by utilizing remote work and strengthen measures, such as avoiding eating places with infection risk when working in the office.
  • Information on the importance of basic infection prevention, such as wearing a mask, should be delivered. It is also necessary to inform that not only scenes with all of the “3Cs” (closed spaces, crowded places, and close contact settings), but scenes of 2 or one alone pose a risk of infection and should be avoided.
  • While replacement by B1.1.7 is ongoing, it is necessary to take measures focusing on understanding the actual situation using virus genomic surveillance in order to reinforce the measures against new mutant strains in line with local infection statuses and evaluations/analyses of epidemiological information. Particularly, for B.1.617 (the mutant strain first detected in India), which has been newly positioned as VOC, it is essential to suppress the spread of infection in Japan as much as possible by following measures: nationwide monitoring through genomic surveillance, strengthening of monitoring systems by performing PCR tests to detect L452R mutation, and active epidemiological surveys. In addition, the border control measures against infection from India, Pakistan, and Nepal have been strengthened. Prompt action will be required based on the occurrence status in other countries.
  • In addition to the proven effect of vaccines to prevent onset of the disease, there have been research reports conducted after clinical use of vaccines in various countries, suggesting effectiveness in the prevention of aggravation and infection. Vaccination with such effects in wider populations can be expected to reduce severe cases and then inhibit the infection of the disease. Vaccination was initiated for the elderly, but it is necessary for the national and local governments to work together to offer vaccinations for many people as quickly and efficiently as possible.

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

Copyright 1998 National Institute of Infectious Diseases, Japan