国立感染症研究所

113th Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (January 11, 2023) Material 1

 

Evaluation of the latest infection status, etc.

Overview of the infection status, etc.

  • The number of new infection cases nationwide last week (by date of report) was approximately 934 per 100,000 of the population, with a ratio of 1.28 of this week to last week. After temporarily decreasing during the year-end and New Year holidays, an increasing trend is continuing again, and the infection level is high.It is necessary to pay attention to the future impact of attenuation of immunity and replacement by variant strains on the infection status.
  • The use rate of beds is on the rise nationwide, exceeding 50% in many regions. The numbers of severe cases, deaths, and problems with ambulance transport show continuous increasing trends. Particularly, the numbers of deaths and problems with ambulance transport continue to exceed previous maximum values.

Reference: Local trend

* The number of new cases of infection is an approximate figure per 100,000 of the population, as the total for the current week, which is the reported number in HER-SYS as of Jan 10, 00:00 AM (the same time point is used for the ratio to the previous week), and the use rate of beds is the secured bed use rate as of the writing of this document on Jan 10.

Infection status and future outlook

Infection status
  • The number of new infection cases nationwide continues to increase again and the infection level is high after temporarily decreasing during the year-end and New Year holidays.
  • There were regional differences in the infection status; Chugoku/Shikoku and Kyushu show greater increases than the nationwide increase, and their numbers per 100,000 of the population are higher than the nationwide number. On the other hand, the numbers per 100,000 people in Hokkaido, Tohoku, Kanto, Hokuriku, and Koshinetsu are lower than the nationwide number. There is an increasing trend in mass infections in facilities for elderly people and medical institutions.
  • The number of new cases of infection per population in each age group has increased significantly among people in their 20s and decreased for people in their teens and younger. The number of new infections among elderly people is increasing in the regions where the infection is spreading. The numbers of severe cases and deaths show continuous increasing trends nationwide. Particularly, the number of deaths has exceeded the previous maximum level, and there is concern that the number will continue to increase.
  • As the reports of deaths among children since January 2022 suggest, attention must be paid to the occurrence of severe cases and deaths as well as the number of hospitalized children associated with an increase in the number of infected children.
  • The incidence of seasonal influenza is lower than during the same period in usual years, but higher than during the same period the previous two years. At the end of last year, the number of weekly reports per fixed-point medical institution exceeded one, and it became a nationwide epidemic. At the time of the announcement last weekend, the number of weekly reports also exceeded two, and it is on an increasing trend.
Future outlook
  • Regarding the future infection status, the number of new infection cases has been increasing and a continued increasing trend is expected in many regions excluding some, despite regional differences and uncertainty, based on the epi curve and the short-term forecast nationwide and in large cities. It is necessary to pay attention to the future impact of attenuation of immunity on the infection status, the increase in the proportion of strains associated with more immune escape, the infection situation in China and the influx into Japan.
  • Concerning the level of seasonal influenza, an increase in infection cases is expected to continue in the days ahead. Attention needs to be paid to simultaneous infection with influenza and COVID-19 after schools resume.
Factors that increase and suppress infection
  1. [Immunity as a result of vaccination and infection]

    With the promotion of vaccination, the proportion of immune carriers against the Omicron variant (BA.4-5) shows an increase in each age group, and it has been reported that the percentage is increasing particularly in the elderly population. However, immunity acquired both through vaccination and natural infection may decline over time.

  2. [Contact status]

    As in usual years, the nighttime population decreases greatly during the year-end and New Year holidays in most areas including large cities.

  3. [Epidemic strains]

    Currently, the BA.5 lineage is the mainstream in Japan, but sublineages of the Omicron variant such as BQ.1 and XBB lineages are considered to have greater immune escape ability, and have been pointed out to predominate among the increasing number of infected people overseas. Particularly regarding the BQ.1 lineage, the proportion is domestically increasing, and close attention is required.

  4. [Climatic and seasonal factors]

    With a full-fledged winter, temperatures are lowering nationwide, and ventilation may be difficult. Respiratory virus infections also tend to be prevalent in winter.

Situation of the medical care provision system
  • Nationwide, the use of beds tended to increase, exceeding 50% in many regions, 70% in some regions, and 80% in Kanagawa. The use rate of beds for severe cases exceeded 40% in some regions.
  • In the field of nursing care, the number of patients treated in facilities is at a high level, and infection is also seen among elderly people and workers.
  • As for emergency medical care, while the medical care system is usually overloaded in winter, the number of cases having difficulty with emergency transportation exceeded the peak at the time of infection spread last summer, showing an increasing trend. Attention should continuously be paid to securing a system to provide emergency medical care.

Measures to be taken

Basic concepts
  • Measures to strengthen and focus the healthcare system should be taken in case of limited medical resources to provide appropriate medical care to elderly people and persons at risk of aggravation. Each citizen will be asked to take voluntary actions to prevent infection to protect those at high risk of aggravation, such as elderly people, and to ensure regular medical care.
  • Based on the decision made by the government’s Novel Coronavirus Response Headquarters on November 18, 2022, measures to prevent the spread of infection will be taken according to the status of outpatient medical care, etc.
  • The national and local governments will remind the public of the need for routine infection control measures, and take measures to support the public's efforts to prevent infection.
  1. 1. Further promotion of vaccinations
    • As for the “vaccine for the Omicron variant," vaccination of all persons aged 12 and over who have completed the first vaccination should proceed.
    • As both vaccines for the BA.1 and the BA.4 and BA.5 lineages are expected to be more effective than the previous vaccines, it is necessary to proceed with vaccination with the vaccine that can be given sooner. All eligible persons who wish to receive vaccination will be asked to receive the vaccine for the Omicron variant.
    • Those who have not received vaccination will be encouraged to consider getting the initial vaccination as soon as possible.
    • For children (ages 5 to 11), booster vaccinations will be promoted along with the initial vaccination. For children (ages 6 months to 4 years), initial vaccinations will be promoted.
    • It is necessary to discuss promptly how to position the coronavirus vaccination in the future.
  2. 2. Use of tests
    • The national and local governments are required to secure a system that enables testing and should further utilize testing.
    • Perform frequent tests (about 2 or 3 times a week for facility workers) for workers at facilities for elderly people.
    • Establishment of a system for fever outpatients should be further promoted, so that patients with symptoms can self-test using an antigen qualitative test kit, and if the result is positive, they can promptly undergo health observation at a health follow-up center, etc.
    • Further promotion of the utilization of antigen qualitative test kits, which have been switched to OTC and are sold on the internet.
  3. 3. Quarantine measures
    • The status of the COVID-19 in China is rapidly worsening, making it difficult to grasp the detailed situation. Based on this situation, temporary measures such as immigration inspections have been implemented since December 30, 2022 to avoid a sharp increase in the inflow of the COVID-19 into Japan, and flexible responses will be taken while monitoring the infection situation in China.
  4. 4. Securing a medical care provision system

    In winter, it is also the time when the number of patients with diseases other than the COVID-19 increases. With the support of the national government, prefectural governments must take measures mainly to avoid overcrowding of hospital beds and fever outpatient clinics as follows.

    • Maintain the total number of beds required for patients infected with the COVID-19 based on the bed securing plan, and promptly increase the number of beds in response to spreading of the infection. In addition, continue to increase the number of medical institutions that can handle COVID-19 by supporting improvement of the ability to treat COVID-19 cases, even at hospitals without any beds for infected patients (promotion of zoning of hospital rooms, etc.).
    • In addition to facilitating the use of available hospital beds and developing temporary medical facilities to supplement hospital beds, making efforts to avoid a shortage of hospital beds and emergency medical care, such as utilization of lodging facilities and resting beds
    • Appropriate adjustment so that patients who need hospital treatment can be hospitalized preferentially (securing and expanding logistical support hospitals, and improving the hospital turnover rate, such as by dissemination of the standard for early discharge of 4 days, as a rule), implementation of frequent examinations at facilities for elderly people and others, and further strengthening medical support during normal times
    • In addition to extending the office hours and the number of outpatient clinics for fever patients, the outpatient medical care system is strengthened and prioritized by strengthening regional outpatient and testing centers and telephone and online clinics, etc.
    • Local residents should be informed that they should refrain from visiting emergency outpatient units only to receive a precautionary examination if they do not have symptoms, for example, taking the actual situation in the region into consideration, so that nobody is prevented from receiving treatment. To respond to concerns and questions when a patient’s physical condition deteriorates, the telephone consultation service by healthcare professionals should be thoroughly publicized, and this service should also be strengthened.
    • Ensuring that workplaces and schools do not require test certificates at the start of medical treatment
  5. 5. Response to simultaneous epidemics of novel coronavirus infection and seasonal influenza
    • Assuming that there are many patients with fever during simultaneous epidemics, the following efforts should be promoted according to the actual situation in each region: strengthening of fever outpatient clinics, strengthening of telephone consultations and telemedicine in preparation for overcrowding of the fever outpatient clinics, expansion of health follow-up centers, securing of self-examination kits, strengthening of the consultation system, and prevention of overcrowded emergency medical care.Furthermore, the smooth supply of therapeutic drugs will be promoted, including oral drugs that are new treatment options for COVID-19 and are prescribed after confirmation of the indication by a doctor. Pharmacies, etc. will be asked to use the consultation service of the Ministry of Health, Labour and Welfare when it is difficult to obtain antipyretic analgesics.
    • The prefectures will work to strengthen and prioritize the health care system based on plans to establish systems such as strengthening of outpatient medical care systems in accordance with the actual conditions in each region.
    • It is necessary to provide information and appropriate messages depending on the status of infection to the public. In addition to calling for preparations such as purchasing the antigen qualitative test kits and antipyretic analgesics, checking the contact information of consultation services, etc., persons at a low risk of severe symptoms will be encouraged to perform self-testing or to utilize their local health follow-up centers. While the emergency medical care system is usually overwhelmed in winter, people will be advised to do the following: check the “guide for ambulance services” in preparation for an acute illness or injury, consult a family doctor when hesitant to call an ambulance, use a telephone consultation service such as #7119, and call an ambulance without hesitation if necessary.
    • At the same time, vaccination against COVID-19 and seasonal influenza of those who are subject to vaccination should be promoted.
    • When the number of infected cases sharply increases and hospitals are overcrowded, measures depending on the situation are required, including requests/calls for residents and business operators to prevent spreading of the infection and to maintain the functions of the medical system, as well as highly effective measures to prevent the spread of infection including behavioral restrictions.
  6. 6. Surveillance and risk assessment, etc.
    • It is necessary to promptly promote consideration of effective and appropriate surveillance to grasp the epidemic status. It is also necessary to continue monitoring of the trends of variants through genomic surveillance.
    • Regarding the risk assessment of COVID-19, it is necessary to continue evaluation of the pathogenicity, infectivity, mutations, etc.
  7. 7. Effective ventilation
    • It is necessary to publicize and recommend effective ventilation methods to prevent insufficient indoor ventilation (how to create airflow considering aerosols and install partitions that do not block airflow, for example) due to the use of heating appliances due to low temperatures.
  8. 8. Re-inspection and implementation of basic infection control

    Re-inspection and implementation of the following basic infection control measures are needed.

    • Continue proper wearing of nonwoven masks according to the situation, hand hygiene, thorough ventilation, etc.
    • Avoid situations with a high risk of infection, such as the three Cs, congestion, or loud voices.
    • In the event of a meeting at a restaurant, choose a venue certified by a third party, keep the number of people as low as possible, avoid speaking in loud voices and staying for a long time, and wear a mask when talking.
    • People with symptoms such as sore throat, cough, and fever should refrain from going out.
    • Refer to guidelines for hospital visits and use of an ambulance.
    • Prepare antigen qualitative test kits and antipyretic analgesics at home, and check the contact information of consultation services.
    • To reduce the chances of contact as far as possible, it is necessary for measures at the workplace, such as again promoting the use of telework.
    • Organizers of events or meetings should fully evaluate the epidemic situation and risk of infection in the area, and consider whether or not to hold the event. If the event is held, measures should be taken to minimize the infection risk.
    • Since the risk of infection remains during the shortened period of home care of those who test positive, they should monitor their own physical condition, such as measuring their own temperature, and taking thorough measures against infection when going out. They must also be asked to avoid contact with people who are at risk of severe disease, such as elderly people.
    • To allow the minimum necessary outings, such as shopping for groceries, after 24 hours have passed since symptoms have subsided or when there are no symptoms, it is necessary to take voluntary actions to prevent infection, such as wearing a mask when going out, keeping contact with other people at the minimum period of time necessary, and not using public transportation.
<< Reference: Findings on the characteristics of the Omicron variant and its sublineages >>
  1. [Infectivity/transmissibility]

    It has been confirmed that compared to the Delta variant, the generation time has shortened to approximately 2 days (approximately 5 days for Delta). The doubling time and incubation period have also shortened, the risk of re-infection and secondary infection after infection has increased, and the speed of infection spread is very fast. According to the reported data, pre-symptomatic transmission has probably occurred to some extent as with the previous strains.

  2. [Place/route of infection]

    In Japan, many cases of infection have occurred through the same opportunities as before (spending time indoors in locations with inadequate ventilation, eating and drinking, etc.), and infection is considered to have occurred via the same routes as before (droplets adhering to the mucosa, aerosol inhalation, contact infection, etc.).

  3. [Severity, etc.]

    It has been shown that infection with the Omicron variant may present a relatively lower risk of hospitalization and aggravation than with the Delta variant. To evaluate COVID-19, including the Omicron variant, it is not only necessary to assess the severity as a disease but also of the transmissibility and the impact on the medical care system and society as a whole.

    Concerning the death toll since the outbreak at the end of 2021, it is reported that the novel coronavirus is not the direct cause of death in quite a number of cases compared to the epidemic in the summer of 2021; for example, when elderly people who had been living in a facility for elderly people since before the infection were infected and died, the death was due to worsening of the underlying disease. There were many cases of serious respiratory failure due to typical viral pneumonia caused by the novel coronavirus infection from the beginning of the novel coronavirus outbreak until the outbreak of the Delta variant. However, during the Omicron variant outbreak, it was reported that other diseases than pneumonia became the main causes of death, such as exacerbation of the underlying disease that had been present before hospitalization and the onset of other complications during hospitalization.

    Concerning the spread of infection last summer, there has been a continuing decrease in the rate of severe cases and increase in the ratio of elderly people among hospitalized patients as during the previous outbreak compared to spreading of the infection in the summer of 2021. Among the deaths during the 2022 summer outbreak, mechanical ventilation/nasal high flow use rates and steroid prescription rates were decreased compared to the 2021 outbreak.

    Among the fatal cases of infected children who died of endogenous factors, there were some cases without any underlying diseases. The reports on the results of on-site investigations have stated that it is necessary to pay attention to neurological symptoms such as convulsions and disturbance of consciousness, and systemic symptoms such as vomiting and poor oral intake besides the respiratory symptoms.

    Among the deaths that occurred at home in July and August last year, approximately 80% of the patients were 70 years and older, which is similar to the trend of all deaths during the same period. It suggests that there were also many deaths caused by other factors than COVID-19. The local governments are developing treatment, testing and follow-up outpatient medical care systems including medical institutions. It is important to continuously endeavor to provide the necessary medical care to home care patients.

  4. [Virus shedding period]

    According to Japanese data, the risk of infection remains until 10 days after onset, and infectivity is high until 7 days after onset. Even after waiting for 5 days, a third of patients are still shedding infectious viruses. On Day 8 (after isolation for 7 days), most patients (approximately 85%) did not shed infectious viruses, and it was reported that even if patients did shed the virus, the amount of virus decreased to one-sixth that in the initial stage of onset after 7 days.

  5. [Vaccine effects]

    Concerning the conventional vaccine, the infection and disease onset prevention effects of the first vaccination against the Omicron variant are markedly reduced. The hospitalization-preventing effect is reported maintained at a certain level for the first 6 months, but subsequently decreases to 50% or less. On the other hand, it has been reported overseas that a third vaccination restores the infection-preventing, disease onset-preventing and hospitalization-preventing effects against infection with the Omicron variant, and information on how these vaccine effects are attenuated after a third vaccination has become available. Concerning the vaccine against the Omicron variant (BA.4-5), it has been reported that the preventive effect against disease onset was observed within 0 to 2 months (median 1 month) after vaccination.

  6. [Sublineages of the Omicron variant]

    While the BA.5 lineage continues to be mainstream in the world, there are many reports of sublineages of the Omicron variant and recombinants with characteristic mutations in the spike protein. There are also sublineages for which superiority in an increase in infected patients has been indicated, including the BQ.1 lineage (sublineages of the BA.5.3 lineage), as well as the XBB lineage (sublineages of the BJ.1 lineage [sublineage of the BA.2.10 lineage] and recombinants of the BM.1.1.1 lineage [sublineage of the BA.2.75.3 lineage]). In Europe, an increase in the proportion of the BQ.1 lineage has been confirmed, which is also increasing in Japan. In addition, the XBB.1.5 lineage (sublineages of the XBB lineage) is on an increasing trend in the US. The World Health Organization (WHO), etc., pointed out that the immune escape of these variants probably leads to dominance in the increasing number of infected cases, but the information obtained so far suggest that there is no epidemiological or clinical knowledge of infectivity or severity of the XBB.1.5 lineage. It is necessary to continue to collect data and analyze the situation and findings in other countries regarding these characteristics of the new sublineages and recombinants, and to continue monitoring by genome surveillance.

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

 

Copyright 1998 National Institute of Infectious Diseases, Japan

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