国立感染症研究所

63th meeting of the COVID-19 advisory board of Ministry of Health, Labour and Welfare (December 16, 2021).  Material 1

 

Evaluation of the latest infection status, etc.

Infection status

  • The number of new cases of infection nationwide (based on the date of reporting) has been decreasing, and the number per 100,000 population has been approximately 0.7 in the last week, the lowest since the summer last year. However, the ratio of this week to last week was 1.17, keeping an upward trend. The numbers of patients receiving treatment, severe patients, and deaths continue to be at a low level.

    Effective reproduction number:On a national basis, the most recent number remains below 1 at 0.96 (as of November 28), with values of 1.01 in the Tokyo metro area and 0.90 in the Kansai area.

Future outlook and measures to be taken

  • Since the Omicron variant was first reported to WHO from South Africa on November 24, cases of infection have been reported in many countries and so-called community-acquired infection has been confirmed in several countries. By December 15, genomic analysis has confirmed that 32 of those who tested positive for corona virus at border-control on return to Japan, had the Omicron variant. Although experimental evaluation of the properties and epidemiological information on the Omicron variant are limited, there is concern about the high infectivity/transmissibility, the risk of reinfection, and its effects on vaccines and therapeutic drugs. Sufficient information on its severity has also not been obtained. To focus on the border-control measures against the Omicron variant and to strengthen the surveillance system in Japan, it is required to administer PCR screening for variants and reinforce whole genome analysis of all positive individuals, particularly positive individuals who have traveled abroad. It is also necessary to continue to collect and analyze WHO and overseas trends, as well as clinical, epidemiological, and virological information, and to take appropriate measures based on evaluation of the infectivity, severity, and impact on vaccine efficacy of the Omicron variant by the National Institute of Infectious Diseases. In addition, when cases of infection caused by the Omicron variant occur in Japan, it is recommended that those who shared the same space as the cases with Omicron variant infection should undergo a wide range of tests regardless of whether they wore a mask or the duration of contact.
  • The number of new cases of infection nationwide is at a very low level, and some regions continue to see no new cases of infection. On the other hand, there are some areas where the spread of infection is still ongoing. In addition, there is a temporary increase in the number of patients in some regions due to clusters at the workplace, social welfare facilities, and primary schools, as well as the occurrence of cases with an unknown route of infection. The nighttime population is also increasing, not only in urban areas but over wide areas. The nighttime population in Tokyo in particular has increased to the highest recorded level at the end of the last October. Indoor activities will increase as it gets colder towards the end of the year, and annual events such as year-end parties and the Christmas and New Year holidays bring opportunities to have interaction with people who do not usually contact each other, and socioeconomic activities are also expected to increase. Therefore, it is necessary to carefully monitor the number of infected patients in the days ahead.
  • Approximately 78% of the country's population has been fully vaccinated with two doses, and approximately 73% of those aged 12 to 19 years have been vaccinated with two doses. To further increase the vaccination rates, it is necessary to promote vaccination of unvaccinated people, and local governments must enhance the communication of information to those who still have to be vaccinated. It is also necessary to steadily implement additional vaccinations, starting in December, for those who wish to receive it.
  • The infection is still being transmitted, and attention should be paid to the future spread of infection. Therefore, it is important to continue basic anti-infection measures such as the correct way of wearing masks, hand washing, avoiding the three Cs, and ventilation among all people, including those who are vaccinated. These basic anti-infection measures are also recommended for the Omicron variant. It is also necessary to select third party-certified restaurants when eating or drinking, to wear a mask when not eating or drinking, and to avoid crowded places with a high risk of infection when going out. In particular, considering that homecoming and travel create opportunities for contacts that do not occur on a daily basis, people must refrain from traveling across prefectures when symptoms such as fever are present. It is also important to proactively see a doctor for symptoms such as mild fever and fatigue to undergo the necessary examinations.

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

 

Copyright 1998 National Institute of Infectious Diseases, Japan

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