65th meeting of the COVID-19 advisory board of Ministry of Health, Labour and Welfare (December 28, 2021). Material 1
Evaluation of the latest infection status, etc.
Infection status
- The number of new cases of infection nationwide (by the reporting date) remains at a very low level of about 1.3 per 100,000 in the most recent week, and in some regions there are days with no new cases of infection. On the other hand, in addition to increase in the number of newly infected people, mainly in urban areas, there is a temporary increase in the number of patients in some regions due to clusters at social welfare and healthcare facilities, and to cases with an unknown route of infection. The most recent week-to-week ratio was 1.51, and increase has continued for more than three weeks.
- Infection with the Omicron variant has been confirmed in multiple regions, and there have been cases where the infection route is unknown at this time, as there is no history of overseas travel.
Effective reproduction number:On a national basis, the most recent number remains above 1 at 1.21 (as of December 12). The figure is 1.22 in the Tokyo metropolitan area and 1.06 in the Kansai area.
Future outlook and measures to be taken
- Although the number of new cases of infection is still very low nationwide, the spread of infection by the Delta variant continues and is increasing. In particular, in Tokyo and Kanagawa, a week-to-week ratio of 1 or more has continued for 2 weeks or longer . The nighttime population has remained near the highest level recorded at the end of October last year in Tokyo. From now, the temperature will further decrease, and indoor activities will increase. In addition, annual events such as the New Year holidays will increase exchanges between people who do not usually meet, and as well as the movement of people going home toward the end of the year and the beginning of the year, which may rapidly spread infections. For this reason, it is necessary to refrain from activities with a high risk of infection, particularly when going home or traveling, including before and after, and limit activities to as few people as possible. Attention should be paid to understanding the trend of infections because the numbers of tests at the end and the beginning of the year are smaller than usual.
- The Omicron variation has been detected around the world and there is a rapid spread of infection that has not been seen in previous mutations. In Japan as well, it is possible that a certain scale of transmission is occurring in regions, and it should be assumed that the infection will spread rapidly.
- Preliminary reports on the properties and epidemiological evaluation of the Omicron variant have been made by international organizations and other countries. Although the information currently available is limited, the epidemic strain is rapidly being replaced from the Delta variant to the Omicron variant in South Africa, the United Kingdom, etc., and there is concern about high transmissibility. Compared to the Delta variant, it has been pointed out that the generation time, doubling time and incubation period are shortened, and the risk of secondary infection and reinfection is increased. It has been reported that although the vaccines’ preventive effect against disease aggravation has been maintained at a certain level, the preventive effect on disease onset is markedly reduced. In vitro evaluations have indicated that some antibody therapeutics may be less effective. All cases of infection with the Omicron variant that are currently being followed up in Japan are mild or asymptomatic. Overseas studies also suggest that the Omicron variant may be less likely to become severe than the Delta variant. However, if the number of infected patients rapidly increases due to the rapid spread of infection, the number of patients requiring hospitalization may rapidly increase, and the medical care provision system may quickly become strained. If infection spreads rapidly among people at high risk of aggravation, the incidence of severe illness or death may increase.
- To focus on the border-control measures against the Omicron variant and to strengthen the surveillance system in Japan, it is necessary to continue to administer PCR screening for variants and whole genome analysis of all positive individuals, particularly positive individuals who have traveled abroad, and those whose epidemiological links in Japan are not clear. In the future, infection may rapidly spread in Japan, and it is necessary to inform the citizens that the focus will be shifted from quarantine measures to domestic measures. In addition, infection with the Omicron variant has been confirmed in Japan, and early detection by thorough implementation of the testing system, prompt and active epidemiological investigation, and implementation of measures to prevent spread of infection are necessary. It is also recommended that those who have 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. Moreover, it is necessary to start taking “comprehensive measures to strengthen prevention, examination and early treatment,” as well as to promote strengthening of the medical care provision system and the public health system according to the situation of infection.
- Amid concerns about the spread of the Omicron variant, it is especially necessary to promote vaccination of unvaccinated people, and local governments must enhance the communication of information to those who still have to be vaccinated. At the same time, the booster vaccination that started in December must also be steadily implemented. In doing so, it is necessary to smoothly carry out the acceleration of the schedule for healthcare professionals and the elderly at high risk of becoming seriously ill, based on the above-mentioned reinforcement measures. In addition, since specially approved oral medications can be used in patients at high risk of mild to moderate aggravation, they are expected to improve access to treatment and have a certain preventive effect on aggravation.
- Since the transmission of infection is still ongoing, attention should be paid to the spread of infection triggered by the coming year-end and New Year holidays. It is highly likely that the Omicron variant is spreading in Japan, and it is necessary to act with the recognition that rapid transmission should be assumed. 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. In regions where infection with the Omicron variant has been confirmed, free tests are available for those who are concerned about infection and wish to have such a test.
- As stated in the discussion by the chairman of the Subcommittee on COVID-19 Measures on December 23, it is necessary to avoid crowded places and places with a high risk of infection when going out. In particular, things such as homecoming and traveling must be carefully considered, in view of the trends of the Omicron variant and opportunities for contact that does not occur on a daily basis. When returning home or traveling, it is now possible to receive free tests conducted by prefectures for those who cannot be vaccinated due to health reasons or for children under 12 years old. Screening is also recommended for vaccinated individuals if they meet with someone who is not vaccinated, or who are at high risk of severe illness if infected. When eating and drinking out, it is necessary to select a third part-certified restaurant having good ventilation, with as few people as possible, avoiding loud noises and long hours, and wearing a mask when not eating or drinking. In order to protect your own life and at the same time to prevent the spread of infection with the Omicron variant, it is recommended to refrain from going out if you feel a little unwell, such as mild fever or fatigue, and to proactively be examined and receive tests.
Figures (Number of new infections reported etc.) (PDF)