国立感染症研究所

44th meeting of the COVID-19 advisory board of Ministry of Health, Labour and Welfare (July 21, 2021).  Material 1

 

Evaluation of the latest infection status, etc.

Infection status

  • The number of new cases of infection nationwide is increasing, with approximately 18 per 100,000 population for the latest week of reporting dates. The ratio of this week to last week continues to increase. The number of new cases of infection is increasing not only in the Tokyo metropolitan area, but also in various regions including the Kansai area. The number of severe patients and deaths has stopped decreasing and remains flat. In addition, the proportion of elderly patients among infected patients continues to decrease.

    Effective reproduction number: On a national basis, it exceeds 1 at 1.17 most recently (as of July 4). In the metropolitan area, the figure is 1.17 in the Tokyo metropolitan area and 1.27 in the Kansai area.

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

    In Tokyo, the number of new cases of infection has continued to increase, reaching approximately 59. The ratio of this week to last week is 1.49 and the infection continues to spread rapidly. The cases of infection are mainly those in their 20s to 40s. The number of infected patients aged 65 years or older has increased but the proportion of them has decreased to approximately 4%. The number of severe patients using mechanical ventilators or artificial heart and lung apparatus remains flat, but the numbers of inpatients and those arranging hospitalization are tending to rise while patients requiring high-flow oxygen have also increased. If the number of infected patients continues to increase at this rate, there are concerns about a delay in arrangement of hospitalization and burdens on the medical systems including general practice. On the other hand, in Saitama, Chiba, and Kanagawa, the number of new cases of infection has also been increasing mainly in those in their 20s and 30s, reaching approximately 27, 27, and 33, respectively. The ratio of this week to last in the 3 prefectures has remained at 1 or higher for 3 weeks or more, reaching 1.87 in Saitama and slightly less than 1.4 in both Chiba and Kanagawa, and the number of infected patients has surged. Those in their 30s or younger account for approximately 60% of the new cases. The use rate of beds for severe patients continues to remain below 20%. In Tokyo, the nighttime population has continued to decrease, but the decreasing speed is slower than that during the time of the last emergency measures. In Saitama, the nighttime population has continued to increase. In Chiba and Kanagawa, the trend has remained flat. It has only been a week since the tightening of measures and it is of great concern that the infection may spread for the time being mainly in Tokyo.

  2. Okinawa

    The number of new cases of infection turns upward, reaching approximately 38. New cases are mainly those in their 20s to 30s. On the other hand, the use rate of beds is tending to decrease with the recent decline in the number of new cases of infection. As for the use rate of beds for severe patients, difficult situations continue. Both the nighttime and daytime populations have increased, and particularly the nighttime population returns to the level before the start of the emergency measures, which gives rise to concerns about the spread of infection.

  3. Kansai area

    In Osaka, the number of new cases of infection has continued to increase mainly in those in their 20s, reaching approximately 24. The ratio of this week to last has remained 1 or higher for 2 weeks, reaching 1.89 with an upward trend. The number of infected patients has surged. The number of inpatients shifts from plateau to increase, but the number of severe patients continues to be on a downward trend. The use rate of beds for severe patients remains flat at approximately 12%. As the nighttime population continues to increase, there are concerns about the continuous spread of infection.
    In Kyoto, Hyogo, and Nara, the number of new cases of infection has been increasing to approximately 11, 11, and 10, respectively. Across the 3 prefectures, the use rate of beds for severe patients continues to be below 20%, but the nighttime population continues to increase in Hyogo and Kyoto. Attention needs to be paid to the future movements.

  4. Other than the above

    The number of new cases of infection turns upward again in Hokkaido, Aichi, and Fukuoka, where the priority measures such as for prevention of the spread of disease were lifted, reaching approximately 12, 7, and 10, respectively. In the 3 prefectures, the use rate of beds and the use rate of beds for severe patients remain below 20%. In Hokkaido, Aichi, and Fukuoka, the nighttime population has increased. Particularly, it has rapidly risen in Hokkaido and Fukuoka. The spread of infection is of concern. The number of new cases of infection has increased in other regions, and attention needs to be paid for such prefectures as Ishikawa and Tottori where the number of new cases has risen to above 15.

Analysis of mutant strains

  • Clusters due to the B.1.617.2 lineage variant (delta variant) have been reported and community-acquired infections have also been observed. The positive rate in the screening tests (mechanical estimation) continues to increase to approximately 21% nationwide. The delta variant is suggested to be more infectious than the B.1.1.7 lineage variant (alpha variant). It is expected that the delta variant will continue to replace the existing strains, and therefore it is necessary to pay close attention to it.

Future outlook and measures to be taken

  • In the most recent situation of infection, the rate of clusters in medical institutions and welfare facilities has decreased. In contrast, infection in workplaces, eating places, schools, and nursing facilities continues to occur, and therefore infection prevention at these places is important. Even for mild cold symptoms, it is necessary to advise people to visit a hospital early and to receive tests using simple kits. Infection often occurs at home. In case of having mild cold symptoms, the person needs to take precautions including wearing a mask even at home.
  • In the past, along with the spread of infection in the Tokyo metropolitan areas, the infection tended to spread over various regions after consecutive holidays. Four consecutive holidays will start from July 22, and the summer vacation and Obon holidays will continue in the days ahead. However, the spread of infection has already been seen in various regions, and each local government needs to work on infection control with a greater sense of crisis to prevent further spread of infection.
  • For that reason, according to the remark titled “To prevent the spread of infection during the summer vacation” dated July 16 issued by the chairman of the Subcommittee on Novel Coronavirus Disease Control, it is necessary to be prudent in moving across prefectures for going back to hometown or traveling, and to minimize the opportunity to gather people who do not usually meet because the risk of the infection spread increases. During the summer vacation including 4 consecutive holidays, it is important to stay at home as much as possible with a family or persons who usually meet.
  • In Tokyo, Okinawa, Saitama, Chiba, Kanagawa, and Osaka, the number of infected patients is rapidly increasing despite the emergency measures and the priority measures, such as for prevention of the spread of disease. It is required to curb the spread of infection early by thoroughly implementing the basic policy revised on July 8. Taking into consideration that infection in eating and drinking places may lead to subsequent infection at home or in the offices, it will be required to take thorough measures for eating and drinking settings including drinking at home and on the street. People are asked to stay at home as much as possible during holidays, and to opt for working from home while ensuring health monitoring and infection control. It is important to refrain from non-essential and non-urgent outings and movements, and to communicate such efforts.
  • Each local government needs to curb the rapid spread by agile intervention based on the situation of infection and the burden of medical care provision systems. Based on the premise that the spread of infection will continue for a certain period, it is required to ensure and coordinate the medical care provision systems and public health systems, including securing accommodation facilities and establishing systems for home medical care.
  • Vaccination has been performed mainly in the elderly, and the proportion of the elderly in the number of new cases of infection has reached the lowest level since autumn last year. Compared with the increase in the number of new cases of infection, the increase in the number of severe patients has been suppressed. In addition, according to the number of infected patients per population by vaccination history, data is showing that the number of infected patients significantly decreased in people aged 65 years or older after receiving the second vaccination, compared to those who did not receive vaccination. Further analyses are needed on these points. As for therapeutic drugs, a new neutralizing antibody drug has obtained fast-track approval, and therefore the treatment options are increasing. On the other hand, the number of the infected patients in their 40s and 50s has been increasing. Efforts to promote vaccination among people other than the elderly should be steadily implemented. As for vaccines, it is also necessary to properly analyze and evaluate the effects associated with the progress of vaccination and to discuss appropriate ways of preventing infection after sufficient progress in vaccination.
  • Regarding the delta variant which has replaced 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, as well as continuously conducting active epidemiological surveys and thorough tests. It is also necessary to continue taking prompt border control measures in line with local statuses of infection.

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

Copyright 1998 National Institute of Infectious Diseases, Japan

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