国立感染症研究所

114th Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (January 17, 2023) Material 1

Evaluation of the latest infection status, etc.

Overview of the infection status, etc.

• The number of new cases of infection nationwide (by date of report) was approximately 712 per 100,000 in the last week, declining again from last week’s upward trend with a ratio of this week to last week of 0.75. 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 exceeds 50% in many regions, and the number of deaths and emergency cases that are difficult to transport are also exceeding the historical maximum.

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 16, 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 16.

Infection status and future outlook

Infection status

• Nationwide, the number of new cases of infection has started to decrease again from the upward trend in the last week.
• There are regional differences in the infection status. In the Tokai, Chugoku, Shikoku and Kyushu regions, the number per 100,000 is higher than the national average, while in the Hokkaido, Tohoku, Kanto, Hokuriku and Koshinetsu regions, the number is lower than the average. Outbreaks have occurred in elderly-care facilities and medical institutions.
• The numbers of new infections by age group nationwide have been decreasing in all age groups, but the extent of decrease is small in patients in their 60s and older and the numbers increase in some regions. The number of severe cases and deaths has leveled off nationwide. However, especially the number of deaths continues to exceed the maximum level at the time of expansion of infections during the last summer. In the recent expansion of infection, the proportion of elderly patients in their 80s and older among newly infected patients continues to increase compared to that at the time of expansion of infections in the last summer, and therefore attention should be continuously paid.
• 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 exceeded 4. In Okinawa, Miyazaki, and Saga, it exceeded 10, showing a nationwide increasing trend.

Future outlook

• Regarding the future infection status, it is expected to be flat or on a decreasing trend nationwide, despite regional differences and uncertainty, based on the epi curves and short-term forecasts 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 that have possibility to escape the immune system, 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.

Factors that increase and suppress infection

1. [Immunity as a result of vaccination and infection]

   With the promotion of vaccination and natural infection, the proportion of immune carriers against the Omicron variant (BA.5 and BQ1.1) shows an increase in each age group, and it has been reported that the percentage is increasing particularly in the elderly population because of vaccination. However, immunity acquired both through vaccination and natural infection may decline over time.

2. [Contact status]

   As in previous years, the nighttime population decreased nationwide during the year-end and New Year holidays and then increased again.

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, particularly XBB.1.5, which as been reported mainly in the US, are considered to have a higher possibility to escape the immune system, and have been pointed out to predominate among the increasing number of infected people overseas. Particularly regarding the BQ.1 lineage, the proportion is increasing domestically, and close attention is required. The proportion of BN.1.2 and BN.1.3 lineages, which are sublineages of the BA.2.75 lineage, has also increased in Japan.

4. [Climatic and seasonal factors]

   With a full-fledged winter, temperatures are dropping 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 rate of beds has exceeded 50% in many regions, 70% in some regions, and 80% in Shiga. 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 maximum level 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

   • As measures for the possibility that there may be many patients with fever during simultaneous epidemics, the following efforts should be promoted according to the actual situation in each region: strengthening of the 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.

     The smooth supply of therapeutic drugs will also 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 infection status to the public. In addition to calling for purchasing the antigen qualitative test kits and antipyretic analgesics as well as 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. In addition, according to the status of handling dead bodies known to be coronavirus positive, the number reported monthly has been the highest during the last December. The proportion of deaths due to coronavirus has recently reached approximately 30%. 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 the 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 limited epidemiological and clinical knowledge of the infectivity and severity of the XBB.1.5 lineage. There are also no clear findings on the BN.1.2 and BN.1.3 lineages, which have been increasing in Japan. 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)

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)

110th Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (December 14, 2022) Material 1

Evaluation of the latest infection status, etc.

Overview of the infection status

• The number of new cases of infection nationwide (by date of report) was approximately 716 per 100,000 of the population in the last week, showing an increasing trend with a ratio of this week to last week of 1.20. However, there were regional differences such as a large increase in some regions. It is also necessary to pay attention to the attenuation of immunity, the impact of replacement by variant strains on the infection status, and increased contact opportunities during the year-end and New Year holidays.
• The use rate of beds is increasing nationwide, and the numbers of severe cases and deaths are increasing.

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 Dec 13, 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 writing of this document on Dec 13.

Infection status and future outlook

Infection status

• The number of new cases of infection is on the rise nationwide, and there are regional differences such as a greater increase in areas where the spread of infection was delayed.
• In Hokkaido, after the number of infections surpassed the peak of the spread of infections this summer, a decreasing trend is continuing. In the Tohoku, Hokuriku, and Koshinetsu regions, the trend has shifted from a decreasing to an increasing trend again. The numbers of increases in the Kinki, Chugoku and Shikoku, Kyushu and Okinawa tend to be larger than the nationwide increase, and there are areas where the number per 100,000 exceeds the national average. There is also an increasing trend in mass infections in facilities for elderly people and medical institutions.
• The number of new cases of infection nationwide by age group has been increasing in all age groups. The number of infected people per population shows a greater increase among younger generations, including teenagers, than in other age groups. The number of new infections among elderly people is increasing in many regions. Since the numbers of severe cases and deaths have been increasing again nationwide, it is necessary to pay attention to future trends.
• As the provisional report of deaths among children since January this year suggests, attention must be paid to the occurrence of severe cases and deaths associated with an increase in the number of infected children.Attention should also be paid to trends in the number of pediatric inpatients.
• The incidence of seasonal influenza is lower than in the same period of usual years, but higher than in the same period of the previous two years, showing a slight increase.

Future outlook

• Regarding the future infection status, an increasing trend is expected in many regions despite regional differences and uncertainty, based on the epi curve and the short-term forecast nationwide and in large cities. In contrast, a decreasing trend is expected to continue in Hokkaido. It is also necessary to pay attention because it is considered that the attenuation of immunity, the situation of replacement by variants with greater immune escape ability, and increased contact opportunities during the year-end and New Year holidays will have an effect on changes in the numbers of infected persons in other areas.
• Concerning the level of seasonal influenza, attention needs to be paid to future changes including simultaneous occurrence with the novel coronavirus infection.

Factors that increase and suppress infection

1. [Immunity as a result of vaccination and infection]

   Immunity acquired both from vaccination and natural infection may decline over time. Although the vaccination rate is higher among people in their 60s and older than in those in their 20s to 40s, the acquisition of immunity by infection is lower, and there is concern about the spread of infection among elderly people.

2. [Contact status]

   There are regional differences in the nighttime population, but the number has increased mainly in large cities such as the Tokyo metropolitan area, Aichi, Osaka, and Fukuoka, compared to the same period last year. There are also concerns about increased opportunities for contact during the year-end and New Year holidays.

3. [Epidemic strains]

   Currently, the BA.5 lineage is the mainstream in Japan, but sublineages of the Omicron variant such as the BQ.1 and XBB lineages are considered to have greater immune escape ability, and it has been pointed out that these are predominant in the increasing number of infected people overseas. Regarding the BQ.1 lineage, in particular, the domestic ratio is increasing, and close attention is required.

4. [Climatic and seasonal factors]

   As winter is approaching and temperatures are dropping nationwide, ventilation may be difficult. In addition, respiratory virus infections tend to be prevalent in winter.

Situation of the medical care provision system

• Nationwide, the use of beds tended to increase, exceeding 30% in almost all regions, and exceeding 50% in North Japan and the Kanto regions. The use rate of beds for severe cases is 0% to 40%, showing regional differences.
• In the field of nursing care, patients are being treated in facilities and infection is seen among elderly people and workers.
• Across the country, the number of cases having difficulty with emergency transportation has increased. In particular, the number of non-COVID-19 cases who have difficulty with ambulance transportation has significantly increased and reached almost the same level as that of the peak of the seventh wave. Attention should be paid to securing a system to provide emergency medical care during the year-end and New Year holidays, in consideration of future trends.

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, 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.
   • Vaccination against the BA.4 and BA.5 lineages has also started. 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. As the vaccination interval from the last vaccination was shortened from at least 5 to at least 3 months, all eligible persons who wish to receive vaccination will be asked to receive the vaccine for the Omicron variant within this year.
   • 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. Securing a medical care provision system

   Prefectural governments must take measures to avoid overcrowding of beds and fever outpatient sections with the support of the national government.

   • Maintain the total number of beds required for patients infected with the COVID-19 based on the bed securing plan. When the infection spreads, increase the number of beds without delay. Also, continue to increase the number of medical institutions that can handle the COVID-19, even hospitals that have no beds for COVID-19, by supporting the improvement of the ability to respond to COVID-19 patients (promotion of zoning hospital room, 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 an emergency outpatient unit only to receive a precautionary examination without symptoms, according to the actual situation in the region. In addition, in order to respond to concerns and questions at the time of worsening physical conditions, the consultation service by healthcare professionals via telephone 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
4. 4. Response to simultaneous epidemics of novel coronavirus infection and seasonal influenza
   • Assuming that there are also many patients with fever during simultaneous epidemics, the following measures should be promoted according to the actual situation of each region: strengthening of fever outpatient clinics, strengthening of telephone and online examination services in preparation for cases of overcrowding at fever outpatient clinics, expansion of health follow-up centers, securing of self-examination kits, and strengthening of the consultation system. The smooth supply of therapeutic drugs will be promoted, including oral drugs that are new treatment options for COVID-19 which are prescribed after confirmation the indication by a doctor.
   • 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 to the public, as well as appropriate messages according to the status of infection. In addition to calling for early preparation of conventional antigen qualitative test kits and antipyretic analgesics, patients are encouraged to visit outpatient clinics or receive treatment according to the risk of severity.
   • To prevent the infections from becoming severe as far as possible, vaccination against COVID-19 and seasonal influenza should be promoted among the target population for vaccination.
   • In case the number of infected persons sharply increases and hospitals are overcrowded, or changes in the characteristics of the viruses increase their pathogenicity, 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.
5. 5. Surveillance and risk assessment, etc.
   • Deterioration of the accuracy of current surveillance is a concern due to the limited scope of notification, prioritization of notification items, delays in testing and diagnosis/reporting due to many infections, and changes in healthcare-seeking behavior. It is necessary to promptly promote consideration of effective and appropriate surveillance to grasp the epidemic status. It is also necessary to continue monitoring the trends of variants through genomic surveillance.
   • Regarding risk assessment, it is necessary to promptly investigate the pathogenicity, infectivity, mutation, etc. of COVID-19.
6. 6. Effective ventilation
   • It is necessary to publicize and recommend effective ventilation methods to prevent insufficient indoor ventilation (how to create airflow considering aerosols, installation of partitions that do not block airflow, etc.).
7. 7. 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.
   • For year-end and New Year parties at restaurants, choose a venue certified by a third party, keep the number of people as small as possible, avoid loud voices and staying a long time, and wear masks 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/antipyretic analgesic at home, etc.
   • 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, eating and drinking, in locations with inadequate ventilation, 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 suggested that infection with the Omicron variant presents a lower risk of hospitalization or aggravation than with the Delta variant. However, analyses to date show that there are more deaths due to infection with the Omicron variant than due to seasonal influenza. It also seems as if the incidence of pneumonia is higher than in case of seasonal influenza, but given the limited data, it has to be investigated by various analyses.

   Concerning the death toll from the outbreak since the end of last year, it is reported that there are many cases in which the novel coronavirus is not the direct cause of death compared to last summer's outbreak, for example, elderly people who have been in a facility for the elderly before the infection are infected but die due to worsening of the underlying disease. There were many cases of serious respiratory failure due to typical viral pneumonia caused by novel coronavirus infection from the beginning of the novel coronavirus outbreak until the Delta variant outbreak. However, during the Omicron variant outbreak, it was reported that other diseases than pneumonia formed the main causes of death, such as exacerbation of the underlying disease that was present before hospitalization and the onset of other complications during hospitalization.

   During spread of the infection this summer, the rate of severe cases decreased compared to that during the previous outbreak and the ratio of elderly people among hospitalized patients increased compared to last summer's outbreak. Among the deaths during this summer’s outbreak, mechanical ventilation/nasal high flow use rates and steroid prescription rates have decreased compared to the outbreak from the end of last year.

   Fatal cases among infected children in whom the cause of death was identified included cases without underlying disease. Preliminary 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 other systemic symptoms than respiratory symptoms, such as vomiting and poor oral intake.

   Among deaths that occurred at home in July and August, approximately 80% of the patients were 70 years and older, which is similar to the trend of all deaths during the same period, suggesting that many patients die from other factors than the novel coronavirus. Local governments are developing outpatient medical care systems including medical examinations/testing institutions and health follow-up systems, and it is important to continuously make efforts to provide the necessary medical care to patients at home.

4. [Virus shedding period]

   According to the 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 the 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 effect]

   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), which are frequently reported in Europe and the United States, as well as the XBB lineage (recombinant of the BJ.1 lineage [sublineage of the BA.2.10 lineage] and the BM.1.1.1 lineage [sublineage of the BA.2.75.3 lineage]), which has been reported mainly in India and Singapore. In Europe and the United States, the proportion of the BQ.1 lineage is increasing in some countries, including Japan. The World Health Organization (WHO), etc., points out that the immune escape of these variants may lead to dominance in increasing the number of infected persons, but the information obtained so far does not suggest that either the infectivity or seriousness of the variants is increasing. 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)

108th Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (November 22, 2022) Material 1

Evaluation of the latest infection status, etc.

Overview of the infection status

• The number of new cases of infection nationwide (by date of report) was approximately 564 per 100,000 of the population in the last week, showing continuing increase with a ratio of this week to last week of 1.15, but with regional differences.
  It is also necessary to pay attention to the attenuation of immunity, the impact on the infection status of replacement by variant strains and, as the new year approaches, increased contact opportunities due to the reactivation of socioeconomic activities.
• The use rate of beds is increasing nationwide, and the numbers of severe cases and deaths are also increasing.

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 Nov 29, 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 Nov 29.

Infection status and future outlook

Infection status

• Nationwide, the number of new cases of infection continued to increase and the ratios to the previous week in all regions except Hokkaido are higher than 1, but the rate of increase is comparatively slow.
• There are regional differences in the current infection status. In Hokkaido, the number of infections has surpassed the peak of the spread of infections this summer, but is now decreasing. Also in the Tohoku, Hokuriku/Koshinetsu, and Chugoku regions, the rate of increase continues to increase, and while there are many regions where the level of infection is high, the rate of increase is slowing down. In contrast, in the Tokyo metropolitan area, Kinki, Kyushu and Okinawa, the number per 100,000 of the population is lower than the national average, but the rate of increase tends to be larger than the national average. In addition, there is an increasing trend in mass infections in facilities for elderly people and medical institutions. In addition, attention should be paid to the increased number of deaths in areas where the number of infected people has increased, such as Hokkaido and Nagano.
• The number of new cases of infection per population in each age group is higher in younger age groups, including teens. However, in some areas, the number of infected people, particularly teens, is flat or tending to decrease. In most regions, the number of new infections in elderly people is increasing, and the numbers of severe cases and deaths also continue to increase.
• As the provisional report of deaths among children since January this year suggests, attention must be paid to the occurrence of severe cases and deaths associated with an increase in the number of infected children.Attention should also be paid to trends in the number of pediatric inpatients.
• The incidence of seasonal influenza is lower than in the same period of usual years, but higher than in the same period of the previous two years, as an increasing trend continues in some regions.

Future outlook

• Regarding the future infection status, the nationwide increase is expected to continue despite regional differences and uncertainty, based on the short-term forecast. It is also necessary to pay attention to the attenuation of immunity, the impact on the infection status of replacement by variants with greater immune escape ability and, as the new year approaches, increased contact opportunities due to the reactivation of socioeconomic activities.
• Since the level of seasonal influenza shows an increasing trend in some regions, attention must be paid to future changes, including simultaneous occurrence with COVID-19.

Factors that increase and suppress infection

1. [Immunity as a result of vaccination and infection]

   Immunity acquired both from vaccination and natural infection may decline over time. Although the vaccination rate is higher among people in their 60s and older than those in their 20s to 40s, the acquisition of immunity by infection is lower, and there is concern about the spread of infection among elderly people. Although the antibody prevalence in the Japanese public, which is based on a survey of antibody prevalence using donated blood samples, is important data, it is simply a preliminary report, and it must be evaluated based on more detailed analysis in the future.

2. [Contact status]

   There are regional differences in the nighttime population, but it is currently trending upward in many regions, including western Japan, and has remained the same or higher compared to the same period last year. Some regions have reached the level before the spread of COVID-19, and there is concern about increased contact opportunities due to the reactivation of socioeconomic activities toward the end of the year.

3. [Epidemic strains]

   Currently, the BA.5 lineage is the mainstream in Japan, but the 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 be predominant in increasing the number of infected people overseas. Particularly regarding the BQ.1 lineage, the proportion may further increase in Japan in the future, and close attention is required.

4. [Climatic and seasonal factors]

   Temperatures are dropping nationwide including northern Japan, and ventilation may be difficult. In addition, respiratory virus infections tend to be prevalent in winter.

Situation of the medical care provision system

• Nationwide, the use of beds tended to increase, exceeding 30% in most regions, and exceeding 50% in regions with a large number of patients. The use rate of beds for severe cases is generally low, but is 20% to 30% in some regions.
• In the field of nursing care, patients are being treated in facilities and infection is seen among elderly people and workers.
• Cases of difficult emergency transportation continue to increase nationwide for both suspected non-COVID-19 cases and suspected COVID-19 cases.

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, 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.
   • Vaccination for the BA.4 and BA.5 lineages has also started. 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. As the vaccination interval from the last vaccination was shortened from at least 5 to at least 3 months, all eligible persons who wish to receive vaccination will be asked to receive the vaccine for the Omicron variant within this year.
   • 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.
   • The initial vaccination for children (aged 6 months to 4 years) has been approved by the PMDA and positioned as an extraordinary vaccination, and initial vaccination in this age group will proceed.
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. Securing a medical care provision system

   Prefectural governments must take measures to avoid overcrowding of beds and fever outpatient sections with the support of the national government.

   • Maintain the total number of beds required for patients infected with the COVID-19 based on the bed securing plan. When the infection spreads, increase the number of beds without delay. Also, continue to increase the number of medical institutions that can handle the COVID-19, even hospitals that have no beds for COVID-19, by supporting the improvement of the ability to respond to COVID-19 patients (promotion of zoning hospital room, 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
   • Expansion and promotion of fever outpatient services, including the use of online medical care, etc.
   • Local residents should be informed that they should refrain from visiting an emergency outpatient unit only to receive a precautionary examination without symptoms, according to the actual situation in the region. In addition, in order to respond to concerns and questions at the time of worsening physical conditions, the consultation service by healthcare professionals via telephone 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
4. 4. Response to simultaneous epidemics of novel coronavirus infection and seasonal influenza
   • Assuming that there are also many patients with fever during simultaneous epidemics, the following measures should be promoted according to the actual situation of each region: strengthening of fever outpatient clinics, strengthening of telephone and online examination services in preparation for cases of overcrowding at fever outpatient clinics, expansion of health follow-up centers, securing of self-examination kits, and strengthening of the consultation system.The smooth supply of therapeutic drugs will be promoted, including oral drugs that are new treatment options for COVID-19 which are prescribed after confirmation the indication by a doctor.
   • The prefectures will formulate plans to establish systems such as strengthening of outpatient medical care systems in accordance with the actual conditions in each region, and will work to strengthen and prioritize the health care system.
   • It is necessary to provide information to the public, as well as appropriate messages according to the status of infection. In addition to calling for early preparation of conventional antigen qualitative test kits and antipyretic analgesics, patients are encouraged to visit outpatient clinics or receive treatment according to the risk of severity.
   • To prevent the infections from becoming severe as far as possible, vaccination against COVID-19 and seasonal influenza should be promoted among the target population for vaccination.
   • In case the number of infected persons sharply increases and hospitals are overcrowded, or changes in the characteristics of the viruses increase their pathogenicity, 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.
5. 5. Surveillance and risk assessment, etc.
   • Deterioration of the accuracy of current surveillance is a concern due to the limited scope of notification, prioritization of notification items, delays in testing and diagnosis/reporting due to many infections, and changes in healthcare-seeking behavior. It is necessary to promptly promote consideration of effective and appropriate surveillance to grasp the epidemic status. It is also necessary to continue monitoring the trends of variants through genomic surveillance.
   • Regarding risk assessment, it is necessary to promptly investigate the pathogenicity, infectivity, mutation, etc. of COVID-19.
6. 6. Effective ventilation
   • It is necessary to publicize and recommend effective ventilation methods to prevent insufficient indoor ventilation (how to create airflow considering aerosols, installation of partitions that do not block airflow, etc.).
7. 7. 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.
   • For year-end and New Year parties at restaurants, choose a venue certified by a third party, keep the number of people as small as possible, avoid loud voices and staying a long time, and wear masks 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/antipyretic analgesic at home, etc.
   • 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 suggested that infection with the Omicron variant presents a lower risk of hospitalization or aggravation than with the Delta variant. However, analyses to date show that there are more deaths due to infection with the Omicron variant than seasonal influenza. It also seems as if the incidence of pneumonia is higher than that of seasonal influenza, but given the limited data, it needs to be investigated by various analyses.

   Concerning the death toll from the outbreak since the end of last year, it is reported that there are many cases in which the novel coronavirus is not the direct cause of death compared to last summer's outbreak, for example, elderly people who have been in a facility for the elderly before the infection are infected but die due to worsening of the underlying disease. There were many cases of serious respiratory failure due to typical viral pneumonia caused by novel coronavirus infection from the beginning of the novel coronavirus outbreak until the Delta variant outbreak. However, during the Omicron variant outbreak, it was reported that other diseases than pneumonia are the main causes of death, such as exacerbation of the underlying disease that was present before hospitalization and the onset of other complications during hospitalization. In the spread of infection this summer, the rate of severe cases has decreased compared to the previous outbreak and the ratio of elderly people among hospitalized patients has increased compared to last summer's outbreak. Among the deaths during this summer’s outbreak, mechanical ventilation/nasal high flow use rates and steroid prescription rates have decreased compared to the outbreak from the end of last year.

   Fatal cases among infected children in whom endogenous death was identified included cases without underlying diseases. Preliminary 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 other systemic symptoms than respiratory symptoms, such as vomiting and poor oral intake.

4. [Virus shedding period]

   According to Japanese data, risk of infection remains until 10 days after onset, and infectivity is high until 7 days after onset. Even after waiting for 5 days, 1/3 of patients are still shedding infectious viruses. On Day 8 (after waiting 7 days), most patients (approximately 85%) had not shed infectious virus, and it was reported that even in those who shed the virus, the amount of virus decreased to one-sixth after 7 days compared to the initial stage.

5. [Vaccine effect]

   For infection with the Omicron variant, the preventive effects of a first vaccination against infection and disease onset are markedly reduced. Its preventive effect on hospitalization is reported to be 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 effect, onset-preventing effect, and hospitalization-preventing effect against infection by the Omicron variant, and information on how these vaccine effects are attenuated after a third vaccination has become available. Regarding the fourth vaccination, it has been reported that while the aggravation-preventing effect was not reduced for 6 weeks, the infection-preventing effect lasted only for a short time.

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 which have 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 and BQ.1.1 lineages (sublineages of the BA.5.3 lineage), which are frequently reported in Europe and the United States, as well as the XBB lineage (recombinant of the BJ.1 lineage [sublineages of the BA.2.10 lineage] and the BM.1.1.1 lineage [sublineages of the BA.2.75.3 lineage]), which has been reported mainly in India and Singapore. In Europe and the United States, the proportion of BQ.1 and BQ.1.1 lineages is increasing in some countries, and it is expected that the proportion will increase further in the future, but at present, a significant increase in the number of infected persons has not been confirmed. The World Health Organization (WHO), etc., points out that the immune escape of these variants may lead to dominance in increasing the number of infected persons, but the information obtained so far does not suggest that either the infectivity or seriousness of the variants is increasing. 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)

107th Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (November 22, 2022) Material 1

Evaluation of the latest infection status, etc.

Overview of the infection status

• The number of new cases of infection nationwide (by date of report) was approximately 474 per 100,000 of the population in the last week, continuing to increase with a ratio of this week to last week of 1.18, but with regional differences such as a ratio less than 1 in some regions.
  It is also necessary to pay attention to the future impact on the infection status of replacement by variant strains and, as the new year approaches, increased contact opportunities due to the reactivation of socioeconomic activities.
• The use rate of beds is increasing nationwide, and the numbers of severe cases and deaths are also increasing.

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 Nov 21, 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 Nov 21.

Infection status and future outlook

Infection status

• Nationwide, the number of new cases of infection continued to increase and the ratios to the previous week in most regions are higher than 1, but the rate of increase has slowed, and some regions are less than 1 compared to last week.
• There are regional differences in the current infection status. In Hokkaido, the number of infections has surpassed the peak of the spread of infections this summer, but the increase has tended to plateau. Also in the Tohoku, Hokuriku/Koshinetsu, and Chugoku regions, the rate of increase continues to increase, and while there are many regions where the level of infection is high, the rate of increase is slowing down. In contrast, an increasing trend can be seen in the Tokyo metropolitan area, Kinki, Kyushu and Okinawa, but they are lower than the national average per 100,000 of the population. In addition, 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 is higher in younger age groups including teens. However, in some areas, the number of infected people, particularly teens, has remained flat or tended to decrease. In most regions, the number of new infections in the elderly continues to increase slowly, and the numbers of severe cases and deaths also tend to increase.
• As the provisional report of deaths among children since January this year suggests, attention must be paid to the occurrence of severe cases and deaths associated with an increase in the number of infected children.Attention should also be paid to trends in the number of pediatric inpatients.
• The incidence of seasonal influenza is lower than in the same period of usual years, but higher than in the same period of the previous two years, as an increasing trend continues in some regions.

Future outlook

• Although there are regional differences and uncertainties in the future infection status, the rate of increase has slowed down and it may reach a peak. However, attention must be paid to the future replacement by variant strains and increased contact opportunities due to the reactivation of socioeconomic activities as the new year approaches, since the number of infected people may not decrease immediately but may level off or increase again.
• Since the level of seasonal influenza shows an increasing trend in some regions, attention must be paid to future changes, including simultaneous occurrence with the novel coronavirus infection.

Factors that increase and suppress infection

1. [Immunity as a result of vaccination and infection]

   Immunity acquired both from vaccination and natural infection may decline over time. Although the vaccination rate is higher among people in their 60s and older than those in their 20s to 40s, the acquisition of immunity by infection is lower, and there is concern about the spread of infection among elderly people.

2. [Contact status]

   There are regional differences in the nighttime population, but the number has remained the same or higher in many regions compared to the same period last year. Some regions have seen rapid increase and reached the level before the spread of COVID-19, and there is concern about increased contact opportunities due to the reactivation of socioeconomic activities toward the end of the year.

3. [Epidemic strain]

   In Japan, the BA.5 lineage has largely become mainstream. It is necessary to pay close attention to the strains that have been pointed out to be dominant in the increase in the number of infected persons overseas, such as the BQ.1 and XBB lineages, as the proportion may increase further in the future.

4. [Climatic and seasonal factors]

   Nationwide, weather conditions are favorable for ventilation, but proper ventilation may be difficult in some regions like northern Japan due to a decline in temperature in the days ahead. In addition, respiratory virus infections tend to increase in winter.

Situation of the medical care provision system

• Nationwide, the use of beds tended to increase, exceeding 30% in regions with a large number of infected patients, and exceeding 50% in some regions. The use rate of beds for severe cases continues at a low level, but we need to watch for effects associated with increase in the number of new cases of infection in the future.
• In the field of nursing care, patients are being treated in facilities and infection is seen among elderly people and workers.
• In cases of difficult emergency transportation, there is an increasing trend nationwide for both suspected non-COVID-19 cases and suspected COVID-19 cases.

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, 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 vaccination
   • As for the “vaccine for the Omicron variant," vaccination of all persons aged 12 and older who have completed the first vaccination should proceed.
   • Vaccination for the BA.4 and BA.5 lineages has also started. 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. As the vaccination interval from the last vaccination was shortened from at least 5 to at least 3 months, all eligible persons who wish to receive vaccination will be asked to receive the vaccine for the Omicron variant within this year.
   • 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.
   • The initial vaccination for children (aged 6 months to 4 years) has been approved by the PMDA and is positioned as an extraordinary vaccination, and initial vaccination in this age group will proceed.
2. 2. Use of tests
   • The national and local governments are required to secure a system that enables testing and should further utilize testing.
   • Performance of 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. Securing a medical care provision system

   Prefectural governments must take measures to avoid overcrowding of beds and fever outpatient clinics with the support of the national government.

   • 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
   • Making appropriate adjustments so that patients requiring inpatient treatment can be hospitalized preferentially, performing frequent tests at facilities for elderly people, etc., and further strengthening medical support
   • 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
   • Promotion of effective and less burdensome measures against infection, such as flexible and efficient use of hospital beds through zoning of each hospital room
   • Expansion and promotion of fever outpatient services, including the use of online medical care, etc., and further promotion of the development of a “fever outpatient self-examination system”
   • Without discouraging the seeking of treatment, local residents should be informed that they should refrain from visiting an emergency outpatient unit only to receive a precautionary examination without symptoms, according to the actual situation in the region. In addition, in order to respond to concerns and questions when physical condition deteriorates, the consultation service by healthcare professionals via telephone 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
4. 4. Response to simultaneous epidemics of novel coronavirus infection and seasonal influenza
   • Assuming that there are also many patients with fever during simultaneous epidemics, the following measures should be promoted according to the actual situation of each region: strengthening of fever outpatient clinics, strengthening of telephone and online examination services in preparation for cases of overcrowding at fever outpatient clinics, smooth supply of therapeutic drugs, expansion of health follow-up centers, securing of self-examination kits, and strengthening of the consultation system.
   • The prefectures will formulate plans to establish systems such as strengthening of outpatient medical care systems in accordance with the actual conditions in each region, and will work to strengthen and prioritize the health care system before the end of November.
   • It is necessary to provide information to the public, as well as appropriate messages according to the status of infection. In addition to calling for early preparation of conventional antigen qualitative test kits and antipyretic analgesics, patients are encouraged to visit outpatient clinics or receive treatment according to the risk of severity.
   • To prevent the infections from becoming severe as far as possible, vaccination against the novel coronavirus as well as the influenza virus should also be promoted among the target population for vaccination.
   • In case the number of infected persons sharply increases and hospitals are overcrowded, or changes in the characteristics of the viruses increase their pathogenicity, 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.
5. 5. Surveillance
   • Deterioration of the accuracy of current surveillance is a concern due to the limited scope of notification, prioritization of notification items, delays in testing and diagnosis/reporting due to many infections, and changes in healthcare-seeking behavior. It is necessary to promptly promote consideration of effective and appropriate surveillance to grasp the epidemic status.
     It is also necessary to continue monitoring the trends of variants through genomic surveillance.
6. 6. Effective ventilation
   • It is necessary to publicize and recommend effective ventilation methods to prevent insufficient indoor ventilation (how to create airflow considering aerosols, installation of partitions that do not block airflow, etc.).
7. 7. 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.
   • For year-end and New Year parties at restaurants, choose a venue certified by a third party, keep the number of people as small as possible, avoid loud voices and staying a long time, and wear masks 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/antipyretic analgesic at home, etc.
   • 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 suggested that infection with the Omicron variant presents a lower risk of hospitalization or aggravation than with the Delta variant. However, analyses to date show that there are more deaths due to infection with the Omicron variant than seasonal influenza. It also seems as if the incidence of pneumonia is higher than that of seasonal influenza, but given the limited data, it needs to be investigated by various analyses.

   Concerning the death toll from the outbreak since the end of last year, it is reported that there are many cases in which the novel coronavirus is not the direct cause of death compared to last summer's outbreak, for example, elderly people who have been in a facility for the elderly before the infection are infected but die due to worsening of the underlying disease. There were many cases of serious respiratory failure due to typical viral pneumonia caused by novel coronavirus infection from the beginning of the novel coronavirus outbreak until the Delta variant outbreak. However, during the Omicron variant outbreak, it was reported that other diseases than pneumonia are the main causes of death, such as exacerbation of the underlying disease that was present before hospitalization and the onset of other complications during hospitalization. In the spread of infection this summer, the rate of severe cases has decreased compared to the previous outbreak and the ratio of elderly people among hospitalized patients has increased compared to last summer's outbreak. Among the deaths during this summer’s outbreak, mechanical ventilation/nasal high flow use rates and steroid prescription rates have decreased compared to the outbreak from the end of last year.

   Fatal cases among infected children in whom endogenous death was identified included cases without underlying diseases. Preliminary 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 other systemic symptoms than respiratory symptoms, such as vomiting and poor oral intake.

4. [Virus shedding period]

   According to Japanese data, risk of infection remains until 10 days after onset, and infectivity is high until 7 days after onset. Even after waiting for 5 days, 1/3 of patients are still shedding infectious viruses. On Day 8 (after waiting 7 days), most patients (approximately 85%) had not shed infectious virus, and it was reported that even in those who shed the virus, the amount of virus decreased to one-sixth after 7 days compared to the initial stage.

5. [Vaccine effect]

   For infection with the Omicron variant, the preventive effects of a first vaccination against infection and disease onset are markedly reduced. Its preventive effect on hospitalization is reported to be 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 effect, onset-preventing effect, and hospitalization-preventing effect against infection by the Omicron variant, and information on how these vaccine effects are attenuated after a third vaccination has become available. Regarding the fourth vaccination, it has been reported that while the aggravation-preventing effect was not reduced for 6 weeks, the infection-preventing effect lasted only for a short time.

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 which have 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 and BQ.1.1 lineages (sublineages of the BA.5.3 lineage), which are frequently reported in Europe and the United States, as well as the XBB lineage (recombinant of the BJ.1 lineage [sublineage of the BA.2.10 lineage] and the BM.1.1.1 lineage [sublineage of the BA.2.75.3 lineage]), which has been reported mainly in India and Singapore. In Europe and the United States, the proportion of BQ.1 and BQ.1.1 lineages is increasing in some countries, and it is expected that the proportion will increase further in the future, but at present, a significant increase in the number of infected persons has not been confirmed. The World Health Organization (WHO), etc., points out that the immune escape of these variants may lead to dominance in increasing the number of infected persons, but the information obtained so far does not suggest that either the infectivity or seriousness of the variants is increasing. 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)

106th Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (November 17, 2022) Material 1

Evaluation of the latest infection status, etc.

Overview of the infection status

• The number of new cases of infection nationwide (by date of report) was approximately 435 per 100,000 of the population in the last week, showing continuing increase with a ratio of this week to last week of 1.24 with regional differences.
• It is also necessary to pay attention to the future impact on the infection status of replacement by variant strains and, as the new year approaches, increased contact opportunities due to the reactivation of socioeconomic activities.
• The use rate of beds is increasing nationwide, and the numbers of severe cases and deaths are also increasing.

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 Nov 16, 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 Nov 16.

Infection status and future outlook

Infection status

• Nationwide, the number of new cases of infection continues to increase, and the ratio to the previous week is over 1.0 in almost all regions. On the other hand, at present, the increase has not been rapid compared to the time of infection expansion this summer.
• There are regional differences in the current infection status, and they are expanding. In Hokkaido, the number of infections has surpassed the peak of the spread of infections this summer, and has reached a record high. In addition, large increases have been seen in the Tohoku, Hokuriku/Koshinetsu, and Chugoku regions. In contrast, the numbers have increased in the Tokyo metropolitan area, Kinki, Kyushu and Okinawa, but are lower than the national average per 100,000 of the population. In addition, 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 is higher in younger age groups including teens. In areas where the number of new cases of infection is high, the increase is especially large among teenagers and younger. Among elderly people, the number of new cases of infection has been increasing, and severe cases and deaths have also tended to increase.
• As the provisional report of deaths among children since January this year suggests, attention must be paid to the occurrence of severe cases and deaths associated with an increase in the number of infected children.Attention should also be paid to trends in the number of pediatric inpatients.
• The incidence of seasonal influenza is lower than in the same period of usual years, but higher than in the same period of the previous two years, showing an increasing trend in some regions.

Future outlook

• Regarding the future infection status in large cities, although there are regional differences and uncertainties in the short term, it is predicted that the number will increase, and there is a possibility that the infection will spread as in the summer this year. It is also necessary to pay attention to the future impact on the infection status of replacement by variant strains and, as the new year approaches, increased contact opportunities due to the reactivation of socioeconomic activities.
• Since the level of seasonal influenza shows an increasing trend in some regions, attention must be paid to future changes, including simultaneous occurrence with the novel coronavirus infection.

Factors that increase and suppress infection

1. [Immunity as a result of vaccination and infection]

   Immunity acquired both from vaccination and natural infection may decline over time. Although the vaccination rate is higher among people in their 60s and older than those in their 20s to 40s, the acquisition of immunity by infection is lower, and there is concern about the spread of infection among elderly people.

2. [Contact status]

   There are regional differences in the nighttime population, but the number has remained the same or higher in many regions compared to the same period last year. Some regions are rapidly increasing, and there is concern about increased contact opportunities due to the reactivation of socioeconomic activities toward the end of the year.

3. [Epidemic strain]

   In Japan, the BA.5 lineage has largely become mainstream. It is necessary to pay close attention to the strains that have been pointed out to be dominant in the increase in the number of infected persons overseas, such as the BQ.1 and XBB lineages, as the proportion may increase further in the future.

4. [Climatic and seasonal factors]

   Nationwide, weather conditions are favorable for ventilation, but proper ventilation may be difficult in some regions like northern Japan due to a decline in temperature in the days ahead. Respiratory virus infections tend to increase in winter.

Situation of the medical care provision system

• Nationwide, the use of beds tended to increase, exceeding 30% in regions with a large number of infected patients, and exceeding 50% in some regions. The use rate of beds for severe cases is at a low level, but we need to watch for effects associated with a further increase in the number of new cases of infection in the future.
• In the field of nursing care, patients are being treated in facilities and infection is seen among elderly people and workers.
• In cases of difficult emergency transportation, there is an increasing trend nationwide for both suspected non-COVID-19 cases and suspected COVID-19 cases.

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, in order to protect those at high risk of aggravation, such as elderly people, and to ensure regular medical care.
• Based on the November 11 report of the novel coronavirus subcommittee, we will take measures to prevent the spread of infection according to the status of outpatient medical care.
• 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 vaccination
   • As for the “vaccine for the Omicron variant," vaccination of all persons aged 12 and older who have completed the first vaccination should proceed.
   • Vaccination for the BA.4 and BA.5 lineages has also started. 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. As the vaccination interval from the last vaccination was shortened from at least 5 to at least 3 months, all eligible persons who wish to receive vaccination will be asked to receive the vaccine for the Omicron variant within this year.
   • 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.
   • The initial vaccination for children (aged 6 months to 4 years) has been approved by the PMDA and is positioned as an extraordinary vaccination, and initial vaccination in this age group will proceed.
2. 2. Use of tests
   • The national and local governments are required to secure a system that enables testing, and should further utilize testing.
   • Performance of 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. Securing a medical care provision system

   Prefectural governments must take measures to avoid overcrowding of beds and fever outpatient clinics with the support of the national government.

   • 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
   • Making appropriate adjustments so that patients requiring inpatient treatment can be hospitalized preferentially, performing frequent tests at facilities for elderly people, etc., and further strengthening medical support
   • 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
   • Promotion of effective and less burdensome measures against infection, such as flexible and efficient use of hospital beds through zoning of each hospital room
   • Expansion and promotion of fever outpatient services, including the use of online medical care, etc., and further promotion of the development of a “fever outpatient self-examination system”
   • Without discouraging the seeking of treatment, local residents should be informed that they should refrain from visiting an emergency outpatient unit without symptoms just to receive a precautionary examination, according to the actual situation in the region. In addition, in order to respond to concerns and questions when physical condition deteriorates, the consultation service by healthcare professionals via telephone 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
4. 4. Response to simultaneous epidemics of novel coronavirus infection and seasonal influenza
   • Assuming that there are also many patients with fever during simultaneous epidemics, the following measures should be promoted according to the actual situation of each region: strengthening of fever outpatient clinics, strengthening of telephone and online examination services in preparation for cases of overcrowding at fever outpatient clinics, smooth supply of therapeutic drugs, expansion of health follow-up centers, securing of self-examination kits, and strengthening of the consultation system.
   • The prefectures will formulate plans to establish systems such as strengthening of outpatient medical care systems in accordance with the actual conditions in each region, and will work to strengthen and prioritize the health care system before the end of November.
   • Efforts will be made to provide information to the public and to call for cooperation at outpatient consultations/treatment depending on the risk of becoming severe and prepare antigen qualitative test kits and antipyretic analgesics, etc. from an early stage. It is also necessary to send appropriate messages according to the infection status.
   • To prevent infections from becoming severe as far as possible, vaccination against the novel coronavirus as well as the influenza virus should also be promoted among the target population.
   • In case the number of infected persons sharply increases and hospitals are overcrowded, or changes in the characteristics of the viruses increase their pathogenicity, 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.
5. 5. Surveillance
   • Deterioration of the accuracy of current surveillance is a concern due to the limited scope of notification, prioritization of notification items, delays in testing and diagnosis/reporting due to many infections, and changes in healthcare-seeking behavior. It is necessary to promptly promote consideration of effective and appropriate surveillance to grasp the epidemic status.
     It is also necessary to continue monitoring the trends of variants through genomic surveillance.
6. 6. Effective ventilation
   • It is necessary to publicize and recommend effective ventilation methods to prevent insufficient indoor ventilation (how to create airflow considering aerosols, installation of partitions that do not block airflow, etc.).
7. 7. 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.
   • Eating and drinking should be done with as few people as possible, and masks should be worn except while eating and drinking.
   • 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/antipyretic analgesic at home, etc.
   • 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 suggested that infection with the Omicron variant presents a lower risk of hospitalization or aggravation than with the Delta variant. However, analyses to date show that there are more deaths due to infection with the Omicron variant than seasonal influenza. It also seems as if the incidence of pneumonia is higher than that of seasonal influenza, but given the limited data, it needs to be investigated by various analyses.

   Concerning the death toll from the outbreak since the end of last year, it is reported that there are many cases in which the novel coronavirus is not the direct cause of death compared to last summer's outbreak, for example, elderly people who have been in a facility for the elderly before the infection are infected but die due to worsening of the underlying disease. There were many cases of serious respiratory failure due to typical viral pneumonia caused by novel coronavirus infection from the beginning of the novel coronavirus outbreak until the Delta variant outbreak. However, during the Omicron variant outbreak, it was reported that diseases other than pneumonia are the main causes of death, such as exacerbation of the underlying disease that was present before hospitalization and the onset of other complications during hospitalization. In the spread of infection this summer, the rate of severe cases decreased compared to the previous outbreak and the ratio of elderly people among hospitalized patients increased compared to last summer's outbreak. Among the deaths during this summer’s outbreak, mechanical ventilation/nasal high flow use rates and steroid prescription rates have decreased compared to the outbreak from the end of last year.

   Fatal cases among infected children in whom endogenous death was identified included cases without underlying diseases. Preliminary 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 other systemic symptoms than respiratory symptoms, such as vomiting and poor oral intake.

4. [Virus shedding period]

   According to Japanese data, risk of infection remains until 10 days after onset, and infectivity is high until 7 days after onset. Even after waiting for 5 days, 1/3 of patients are still shedding infectious viruses. On Day 8 (after waiting 7 days), most patients (approximately 85%) had not shed infectious virus, and it was reported that even in those who shed the virus, the amount of virus decreased to one-sixth after 7 days compared to the initial stage.

5. [Vaccine effect]

   For infection with the Omicron variant, the preventive effects of a first vaccination against infection and disease onset are markedly reduced. Its preventive effect on hospitalization is reported to be 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 effect, onset-preventing effect, and hospitalization-preventing effect against infection by the Omicron variant, and information on how these vaccine effects are attenuated after a third vaccination has become available. Regarding the fourth vaccination, it has been reported that while the aggravation-preventing effect was not reduced for 6 weeks, the infection-preventing effect lasted only for a short time.

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 which have 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 and BQ.1.1 lineages (sublineages of the BA.5.3 lineage), which are frequently reported in Europe and the United States, as well as the XBB lineage (recombinant of the BJ.1 lineage [sublineage of the BA.2.10 lineage] and the BM.1.1.1 lineage [sublineage of the BA.2.75.3 lineage]), which has been reported mainly in India and Singapore. In Europe and the United States, the proportion of BQ.1 and BQ.1.1 lineages is increasing in some countries, and it is expected that the proportion will increase further in the future, but at present, a significant increase in the number of infected persons has not been confirmed. The World Health Organization (WHO), etc., points out that the immune escape of these variants may lead to dominance in increasing the number of infected persons, but the information obtained so far does not suggest that either the infectivity or seriousness of the variants is increasing. 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)

105th Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (November 9, 2022) Material 1

Evaluation of the latest infection status, etc.

Overview of the infection status

• The number of new cases of infection nationwide (by date of report) was approximately 338 per 100,000 of the population in the last week, showing an increasing trend with a ratio of this week to last week of 1.40 and regional differences.
  It is also necessary to pay attention to the future impact of increased contact opportunities due to the reactivation of socioeconomic activities on the infection status.
• The use rate of beds is increasing nationwide, and the number of severe cases is increasing, but the number of deaths has remained flat.

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 Nov 8, 00:00 AM (the same time point is used for the ratio to the previous week), and the use rate of beds is a figure as of the writing of this document on Nov 8.

Infection status and future outlook

Infection status

• Nationwide, the number of new cases of infection has increased and the ratio to the previous week is over 1.0. On the other hand, at present, the increase has not been rapid compared to the time of infection expansion this summer.
• There are regional differences in the current status of infection. In Hokkaido, the level was high around the peak of infection spread in the summer this year, and there has been an increase in many regions including the Tohoku, Hokuriku, Koshinetsu and Chugoku regions. In contrast, the numbers per 100,000 of the population in the Tokyo metropolitan area, Kyushu and Okinawa are lower than the national average. There are also still mass infections in some facilities for elderly people and medical institutions.
• The number of new cases of infection per population in each age group is higher in younger age groups including teens. In areas where the number of new cases of infection is high, the increase is especially large among teenagers and young people. The number of new cases of infection and severe cases among elderly people has also been increasing and the number of deaths has leveled off.
• As the provisional report of deaths among children since January this year suggests, attention must be paid to the occurrence of severe cases and deaths associated with an increase in the number of infected children.
  Attention should also be paid to trends in the number of pediatric inpatients.

Future outlook

• Regarding the future infection status, the number of cases of infection may continue to increase and lead to spreading of the infection, as in the summer this year, despite regional differences and uncertainty, based on the short-term forecast in large cities. It is also necessary to pay attention to the future impact of increased contact opportunities due to reactivation of socioeconomic activities on the infection status.
• The level of seasonal influenza is low at present, but attention needs to be paid to future changes including simultaneous occurrence with the novel coronavirus infection.

Factors that increase and suppress infection

1. [Immunity as a result of vaccination and infection]

   Immunity acquired both from vaccination and natural infection may decline over time. Although the vaccination rate is higher among people in their 60s and older than those in their 20s to 40s, the acquisition of immunity by infection is lower, and there is concern about the spread of infection among elderly people.

2. [Contact patterns]

   Although there are regional differences, the nighttime population has remained almost flat recently. There is concern about increased contact opportunities due to the reactivation of socioeconomic activities toward the end of the year.

3. [Epidemic strain]

   In Japan, the BA.5 lineage has largely become mainstream. It is necessary to pay close attention to the strains that have been pointed out to be dominant in the increase in the number of infected persons overseas, such as BQ.1 and BQ.1.1 lineages (sublineages of the BA.5.3 lineage), as the proportion may increase further in the future.

4. [Climatic and seasonal factors]

   Weather conditions are currently favorable for ventilation, but proper ventilation may be difficult due to a decline in temperature in the days ahead.
   In addition, respiratory virus infections tend to increase in winter.

Situation of the medical care provision system

• Nationwide, the use of beds tended to increase, exceeding 30% in regions with a large number of infected patients. The use rate of beds for severe cases is at a low level, but we need to watch for effects associated with a further increase in the number of new cases of infection in the future.
• In the field of nursing care, patients are being treated in facilities and infection is seen among elderly people and workers.
• Cases of problems with emergency transportation have been increasing nationwide both for suspected non-COVID-19 cases and suspected COVID-19 cases and in some areas the problem is severe.

Measures to be taken

Basic concepts

• To address re-spreading of the novel coronavirus infection and simultaneous seasonal influenza epidemics, 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, and strengthening and prioritization of the health care system will be promoted to protect those at high risk of aggravation, such as elderly people, and to ensure regular medical care.
• 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.
   • Vaccination for the BA.4 and BA.5 lineages has also started. 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. As the vaccination interval from the last vaccination was shortened from 5 to 3 months, all eligible persons who wish to receive vaccination will be asked to receive the vaccine for the Omicron variant within this year.
   • 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.
   • The initial vaccination for children (aged 6 months to 4 years) has been approved by the PMDA and positioned as an extraordinary vaccination, and initial vaccination in this age group will proceed.
2. 2. Use of tests
   • Based on the recommendations of the 17th meeting of the Novel Coronavirus Subcommittee, the national and local governments are required to secure a system that enables testing, and 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. Securing a medical care provision system
   • Prefectural governments must take measures to avoid overcrowding of beds and fever outpatient sections with the support of the national government.
   • 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
   • Making appropriate adjustments so that patients requiring inpatient treatment can be hospitalized preferentially, performing frequent tests at facilities for elderly people, etc., and further strengthening medical support
   • 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
   • Promotion of effective and less burdensome measures against infection, such as flexible and efficient use of hospital beds through zoning of each hospital room
   • Expansion and promotion of fever outpatient services, including the use of online medical care, etc., and further promotion of the development of a “fever outpatient self-examination system”
   • Local residents should be informed that they should refrain from visiting an emergency outpatient unit only to receive a precautionary examination without symptoms, according to the actual situation in the region. In addition, in order to respond to concerns and questions at the time of worsening physical conditions, the consultation service by healthcare professionals via telephone 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
4. 4. Response to simultaneous epidemics of novel coronavirus infection and seasonal influenza
   • Assuming that there are also many patients with fever during simultaneous epidemics, the following measures should be promoted according to the actual situation of each region: strengthening of fever outpatient clinics, strengthening of telephone and online examination services in preparation for cases of overcrowding at fever outpatient clinics, smooth supply of therapeutic drugs, expansion of health follow-up centers, securing of self-examination kits, and strengthening of the consultation system.
   • The prefectures will formulate plans to establish systems such as strengthening of outpatient medical care systems in accordance with the actual conditions in each region.
   • Efforts will also be made to provide information to the public and to call for cooperation at outpatient consultations/treatment depending on the risk of becoming severe and prepare antigen qualitative test kits and antipyretic analgesics, etc. from an early stage.
   • To prevent the infection of infected patients from becoming severe as far as possible, vaccination against the novel coronavirus as well as the influenza virus should also be promoted among the target population for vaccination.
   • In case the number of infected persons sharply increases and hospitals are overcrowded, or changes in the characteristics of the viruses increase their pathogenicity, 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.
5. 5. Surveillance
   • Deterioration of the accuracy of current surveillance is a concern due to the limited scope of notification, prioritization of notification items, delays in testing and diagnosis/reporting due to many infections, and changes in healthcare-seeking behavior. It is necessary to promptly promote consideration of effective and appropriate surveillance to grasp the epidemic status.
     It is also necessary to continue monitoring the trends of variants through genomic surveillance.
6. 6. Effective ventilation
   • Based on the recommendations of the 17th meeting of the Novel Coronavirus Subcommittee, it is necessary to publicize and recommend effective ventilation methods to prevent insufficient indoor ventilation (how to create airflow considering aerosols, installation of partitions that do not block airflow, etc.).
7. 7. 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.
   • Eating and drinking should be done with as few people as possible, and masks should be worn except while eating and drinking.
   • 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/antipyretic analgesic at home, etc.
   • 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 suggested that infection with the Omicron variant presents a lower risk of hospitalization or aggravation than with the Delta variant. However, analyses to date show that there are more deaths due to infection with the Omicron variant than seasonal influenza. It also seems as if the incidence of pneumonia is higher than that of seasonal influenza, but given the limited data, it needs to be investigated by various analyses.

   Concerning the death toll from the previous outbreak, it is reported that there are many cases in which the novel coronavirus infection is not the direct cause of death compared to last summer's outbreak, for example, elderly people who have been in a facility for the elderly before the infection are infected but die due to worsening of the underlying disease. There were many cases of serious respiratory failure due to typical viral pneumonia caused by novel coronavirus infection from the beginning of the novel coronavirus outbreak until the Delta variant outbreak. However, during the Omicron variant outbreak, it was reported that other diseases than pneumonia are the main causes of death, such as exacerbation of the underlying disease that was present before hospitalization and the onset of other complications during hospitalization.

   In the current spread of infection, the rate of severe cases has decreased compared to the previous outbreak and the ratio of elderly people among hospitalized patients has increased compared to last summer's outbreak. Among the deaths during this outbreak, mechanical ventilation/nasal high flow use rates and steroid prescription rates have decreased compared to the previous outbreak.
   Among fatal cases in which endogenous death was identified in infected children, cases without underlying diseases were also found. Preliminary 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 other than respiratory symptoms such as vomiting and poor oral intake.

4. [Virus shedding period]

   According to Japanese data, risk of infection remains until 10 days after onset, and infectivity is high until 7 days after onset. Even after waiting for 5 days, 1/3 of patients are still shedding infectious viruses. On Day 8 (after waiting 7 days), most patients (approximately 85%) had not shed infectious virus, and it was reported that even in those who shed the virus, the amount of virus decreased to one-sixth after 7 days compared to the initial stage.

5. [Vaccine effect]

   For infection with the Omicron variant, the preventive effects of a first vaccination against infection and disease onset are markedly reduced. Its preventive effect on hospitalization is reported to be 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 effect, onset-preventing effect, and hospitalization-preventing effect against infection by the Omicron variant, and information on how these vaccine effects are attenuated after a third vaccination has become available. Regarding the fourth vaccination, it has been reported that while the aggravation-preventing effect was not reduced for 6 weeks, the infection-preventing effect lasted only for a short time.

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 which have 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 and BQ.1.1 lineages (sublineages of the BA.5.3 lineage), which are frequently reported in Europe and the United States, as well as the XBB lineage (recombinant of the BJ.1 lineage [sublineage of the BA.2.10 lineage] and the BM.1.1.1 lineage [sublineage of the BA.2.75.3 lineage]), which has been reported mainly in India and Singapore. In Europe and the United States, the proportion of BQ.1 and BQ.1.1 lineages is increasing in some countries, and it is expected that the proportion will increase further in the future, but at present, a significant increase in the number of infected persons has not been confirmed. The World Health Organization (WHO), etc., points out that the immune escape of these variants may lead to dominance in increasing the number of infected persons, but the information obtained so far does not suggest that either the infectivity or seriousness of the variants is increasing. 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)

104th Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (October 26, 2022) Material 1

Evaluation of the latest infection status, etc.

Overview of the infection status

• Nationwide, the number of new cases of infection (by date of report) was approximately 191 per 100,000 in the current week, and the ratio to the previous week was 0.96. The number of new cases of infection increased in the previous week, but it remained at the same level in the current week. We need to carefully watch the future trend of infection.
  It is also necessary to pay attention to the future impact of increased contact opportunities due to the reactivation of socioeconomic activities on the infection status.
• On the other hand, the use rate of beds is at a low level, while the number of severe patients and deaths has stopped decreasing.

Reference: Local trends

* The number of new cases of infection is an approximate figure per 100,000 as the total for the current week, which is the reported number in HER-SYS as of Oct 25, 00:00 AM (same time point for the ratio to the previous week), and the use rate of beds is a figure as of the writing of this document on Oct 25.

Infection status and future outlook

Infection status

• Nationwide, the number of new cases of infection increased in the previous week, but it remained at the same level in the current week. We need to carefully watch the future trend of infection.
• There are regional differences in the current status of infection, with a significant increase in the Hokkaido, Tohoku, Hokuriku-Koshinetsu, and Chugoku regions, but the number of cases of infection per 100,000 people in the Tokyo metropolitan area and Kyushu/Okinawa is lower than the nationwide number. There are also still mass infections in some facilities for elderly people and medical institutions.
• The number of new cases of infection per population in each age group is higher in younger age groups including teens. The number of new cases of infection among teens is also increasing in regions where the number of new cases of infection is increasing. The number of new cases of infection among elderly people slightly increased, but the numbers of severe patients and deaths stopped decreasing.
• As the provisional report of deaths among children since January this year suggests, attention must be paid to the occurrence of severe cases and deaths associated with an increase in the number of infected children.

Future outlook

• Regarding the future infection status, the number of cases of infection may remain at the same level or continue to increase despite regional differences and uncertainty, based on the short-term forecast in large cities. It is also necessary to pay attention to the future impact of increased contact opportunities due to the reactivation of socioeconomic activities on the infection status.
• Based on the trends of the past two years, there are concerns that the spread of the novel coronavirus infection may start earlier this winter.
  There is also concern that the seasonal influenza epidemic may start earlier than usual, and that these two may occur simultaneously, although the number of cases of seasonal influenza is currently low.

Factors that increase and suppress infection

1. [Immunity as a result of vaccination and infection]

   Immunity acquired from vaccination and natural infection may decline over time. Although the vaccination rate is higher among people in their 60s and older than those in their 20s to 40s, the acquisition of immunity by infection is lower, and there is concern about the spread of infection among elderly people.

2. [Contact patterns]

   The nighttime population is increasing in many regions including Hokkaido, Tokyo, Aichi, Osaka, and Okinawa. There is also concern about increased contact opportunities due to the reactivation of socioeconomic activities toward the end of the year.

3. [Epidemic strain]

   In Japan, the BA.5 lineage has largely become mainstream, and is replacing others. At present, there is not a trend toward further replacement by another lineage.

4. [Climatic and seasonal factors]

   Weather conditions are currently favorable for ventilation, but proper ventilation may be difficult on days with a low temperature or bad weather such as heavy rainfall.
   Respiratory virus infections tend to increase in winter.

Situation of the medical care provision system

• Nationwide, the use rate of beds is at a low level below 30% in most regions. The use rate of beds for severe cases is also at a low level, but we need to watch for effects associated with an increase in the number of new cases of infection in the future.
• In the field of nursing care, patients are being treated in facilities and infection is seen among elderly people and workers.
• Cases of problems with emergency transportation remain on the same level nationwide both for suspected non-COVID-19 cases and suspected COVID-19 cases.

Measures to be taken

Basic concepts

• To prepare for re-spreading of the novel coronavirus infection and simultaneous seasonal influenza epidemics, measures to strengthen and focus the healthcare system should be taken for 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 and strengthening and prioritization of the health care system will be promoted to protect those at high risk of aggravation, such as elderly people, and to ensure regular medical care.
• 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.
   • Vaccination for the BA.4 and BA.5 lineages has also started. As both vaccines for the BA.1 and for 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. As the vaccination interval from the last vaccination was shortened from 5 months to 3 months, all eligible persons will be asked to receive the vaccine for the Omicron variant within this year.
   • 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.
   • The initial vaccination for children (aged 6 months to 4 years) has been approved by the PMDA and positioned as an extraordinary vaccination, and initial vaccination in this age group will proceed.
2. 2. Use of tests
   • Based on the recommendations of the 17th meeting of the Novel Coronavirus Subcommittee, the national and local governments are required to secure a system that enables testing, and 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. Securing a medical care provision system
   • Prefectural governments must take measures to avoid overcrowding of beds and fever outpatient sections with the support of the national government.
   • 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
   • Making appropriate adjustments so that patients requiring inpatient treatment can be hospitalized preferentially, performing frequent tests at facilities for elderly people, etc., and further strengthening medical support
   • 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
   • Promotion of effective and less burdensome measures against infection, such as flexible and efficient use of hospital beds through zoning of each hospital room
   • Expansion and promotion of fever outpatient services, including the use of online medical care, etc., and further promotion of the development of a “fever outpatient self-examination system”
   • Local residents should be informed that they should refrain from visiting an emergency outpatient unit only to receive a precautionary examination without symptoms, according to the actual situation in the region. In addition, in order to respond to concerns and questions at the time of worsening physical conditions, the consultation service by healthcare professionals via telephone 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
4. 4. Response to simultaneous epidemics of novel coronavirus infection and seasonal influenza
   • Assuming that there are many patients with fever during simultaneous epidemics, the following measures should be promoted according to the actual situation in each region: strengthening of fever outpatient clinics, strengthening of telephone and online examination services in preparation for cases of overcrowding at fever outpatient clinics, smooth supply of therapeutic drugs, expansion of health follow-up centers, securing of self-examination kits, and strengthening of the consultation system.
   • The prefectures will formulate plans to establish systems such as strengthening of outpatient medical care systems in accordance with the actual conditions in each region.
   • In addition, efforts will be made to provide information to the public and to call for cooperation at clinic visits/treatment according to the risk of aggravation.
   • To prevent the infection of infected patients from becoming severe as far as possible, vaccination against the novel coronavirus as well as the influenza virus should also be promoted among the target population for vaccination.
   • In case the number of infected persons sharply increases and hospitals are overcrowded, or changes in the characteristics of the viruses increase their pathogenicity, 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.
5. 5. Surveillance
   • Deterioration of the accuracy of current surveillance is a concern due to the limited scope of notification, prioritization of notification items, delays in testing and diagnosis/reporting due to many cases of infection, and changes in healthcare-seeking behavior. It is necessary to promptly develop an effective and appropriate surveillance program to grasp the epidemic status.
     It is also necessary to continue monitoring the trends of variants through genomic surveillance.
6. 6. Effective ventilation
   • Based on the recommendations of the 17th meeting of the Novel Coronavirus Subcommittee, it is necessary to publicize and recommend effective ventilation methods to prevent insufficient indoor ventilation (how to create airflow considering aerosols, installation of partitions that do not block airflow, etc.).
7. 7. 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.
   • Eating and drinking should be done with as few people as possible, and masks should be worn except while eating and drinking.
   • 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.
   • 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 a risk of infection remains during the shortened period of home care of patients who test positive, patients should monitor their own physical condition, such as measuring their temperature, and take 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 (it is 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 mucosa, aerosol inhalation, contact infection, etc.).

3. [Severity]

   It has been suggested that infection with the Omicron variant presents a lower risk of hospitalization or aggravation than the Delta variant. However, analyses to date show that the fatality due to infection with the Omicron variant is higher than that due to seasonal influenza. It is also suggested that the incidence of pneumonia is higher than that of seasonal influenza, but given the limited data, it needs to be investigated by various analyses.

   Concerning the death toll from the previous outbreak, it is reported that there are many cases in which the novel coronavirus infection is not the direct cause of death compared to last summer's outbreak, for example, elderly people who have been in a facility for the elderly before the infection are infected but die due to worsening of the underlying disease. There were many cases of serious respiratory failure due to typical viral pneumonia caused by novel coronavirus infection from the beginning of the novel coronavirus outbreak until the Delta variant outbreak. However, during the Omicron variant outbreak, it was reported that other diseases than pneumonia are the main causes of death, such as exacerbation of the underlying disease that was present before hospitalization and the onset of other complications during hospitalization.

   In the current spread of infection, the rate of severe cases has decreased compared to the previous outbreak and the ratio of elderly people among hospitalized patients has increased compared to last summer's outbreak. Among the deaths during this outbreak, mechanical ventilation/nasal high flow use rates and steroid prescription rates have decreased compared to the previous outbreak.
   Fatal cases among infected children in whom endogenous death was identified included cases without underlying diseases. Preliminary 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 other systemic symptoms than respiratory symptoms, such as vomiting and poor oral intake.

4. [Virus shedding period]

   According to the Japanese data, the risk of spreading infection remains until 10 days after onset, and infectivity is high until 7 days after onset. Even after isolation for 5 days, 1/3 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 shed the virus, the amount of virus decreased to one-sixth that in the initial stage of onset after 7 days.

5. [Vaccine effect]

   Concerning infection with the Omicron variant, the preventive effects of the initial immunization against infection and disease onset are markedly reduced. Its hospitalization-preventing effect is reported to be 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 effect, onset-preventing effect, and hospitalization-preventing effect against infection by the Omicron variant, and information on how these vaccine effects are attenuated after a third vaccination has become available. Regarding the fourth vaccination, it has been reported that while the aggravation-preventing effect was not reduced for 6 weeks, the infection-preventing effect lasted only for a short time.

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 and BQ.1.1 lineages (sublineages of the BA.5.3 lineage), which are frequently reported in Europe and the United States, as well as the XBB lineage (recombinant of the BJ.1 lineage [sublineages of the BA.2.10 lineage] and the BM.1.1.1 lineage [sublineages of the BA.2.75.3 lineage]), which has been reported mainly in India and Singapore. In Europe and the United States, there is concern that the proportion of the BQ.1 and BQ.1.1 lineages will increase in the future. However, no clear findings on the infectivity and severity of these variants have been obtained.

   It is necessary to continue to collect 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)

103rd Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (October 20, 2022) Material 1

Evaluation of the latest infection status, etc.

Overview of the infection status

• Nationwide, the number of new cases of infection (by date of report) was approximately 197 per 100,000 in the last week, and ratio to the previous week was 1.35. As the rate has increased, we need to carefully watch the speed of increase and also whether this trend will continue in the future.
  It is also necessary to pay attention to the future impact of increased contact opportunities due to the reactivation of socioeconomic activities on the infection status.
• In contrast, the use rate of beds is generally on a downward trend, at a low level. The numbers of severe cases and deaths have stopped decreasing.

Local trends

* The value of new cases of infection is the number of persons per 100,000 among the total number for the latest week, based on the reporting dates.

1. Hokkaido

   The number of new cases of infection was approximately 397 (approximately 355 in Sapporo City), and the ratio to the previous week was 1.60. The use rate of beds is approximately 20%.

2. North Kanto

   In Ibaraki, Tochigi, and Gunma, the numbers of new cases of infection were approximately 190, 188, and 224, and the ratios to the previous week were 1.47, 1.34, and 1.35, respectively.
   The use rates of beds were slightly over 20% in Ibaraki and Gunma, and slightly over 10% in Tochigi.

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

   The number of new cases of infection in Tokyo was approximately 169, and the ratio to the previous week was 1.25. The use rate of beds was slightly over 10%, while the use rate of beds for severe cases was below 10%.
   In Saitama, Chiba, and Kanagawa, the numbers of new cases of infection were approximately 152, 145, and 146, respectively, and the ratios to the previous week were 1.23, 1.20, and 1.16, respectively.
   The use rates of beds were approximately 20% in Saitama, slightly under 20% in Kanagawa and slightly over 10% in Chiba.

4. Chukyo/Tokai

   The number of new cases of infection in Aichi was approximately 151, and the ratio to the previous week was 1.28. The use rate of beds was slightly over 20%.
   In Gifu, Shizuoka, and Mie, the numbers of new cases of infection were approximately 249, 191, and 217, and the ratios to the previous week were 1.46, 1.43, and 1.45, respectively.
   The use rates of beds were slightly over 10% in Gifu, slightly under 20% in Shizuoka, and approximately 20% in Mie.

5. Kansai area

   The number of new cases of infection in Osaka was approximately 205, and the ratio to the previous week was 1.40. The use rate of beds was slightly over 10%, while the use rate of beds for severe cases was below 10%.
   In Shiga, Kyoto, Hyogo, Nara, and Wakayama, the numbers of new cases of infection were approximately 220, 133, 157, 191, and 282, and the ratios to the previous week were 1.33, 1.22, 1.49, 1.47, and 1.75, respectively.
   The use rates of beds were slightly over 20% in Shiga, approximately 20% in Wakayama, and slightly over 10% in Hyogo, Kyoto and Nara.

6. Kyushu

   The number of new cases of infection in Fukuoka was approximately 153, and the ratio to the previous week was 1.38. The use rate of beds was approximately 10%.
   In Saga, Nagasaki, Kumamoto, Oita, Miyazaki, and Kagoshima, the numbers of new cases of infection were approximately 178, 148, 186, 188, 169, and 134, and the ratios to the previous week were 1.33, 1.25, 1.28, 1.41, 1.26, and 1.01, respectively. The use rates of beds were slightly over 10% in Kumamoto, Oita, and Kagoshima, approximately 10% in Nagasaki and Miyazaki, and slightly under 10% in Saga.

7. Okinawa

   The number of new cases of infection was approximately 132, and the ratio to the previous week was 0.85. The use rate of beds was approximately 10%, and the use rate of beds for severe cases was slightly under 10%.

8. Other areas than the above

   In Iwate, Yamagata, Toyama and Kagawa the ratios to the previous week were 1.53, 1.56, 1.51, and 1.60, respectively. The use rates of beds were slightly over 20% in Aomori, Akita, Fukushima, Ishikawa, Nagano and Hiroshima.

Infection status and future outlook

Infection status

• Nationwide, the number of new cases of infection increased and the ratios to the previous week in almost all regions are higher than 1. We need to carefully watch the speed of increase as well as whether this trend will continue in the future. It is also necessary to consider the effect of consecutive holidays in the last week. The numbers of new cases of infection have increased in many regions of northern Japan. There are also still mass infections in some facilities for elderly people and medical institutions.
• The number of new cases of infection by age group increased in almost all age groups, and new patients per population were higher in younger age groups. The number of new cases of infection among elderly people also increased, and the numbers of severe cases and deaths stopped decreasing.
• As the provisional report of deaths among children since January this year suggests, attention must be paid to the occurrence of severe cases and deaths associated with an increase in the number of infected children.

Future outlook

• Regarding the future infection status, the number of infections may continue to increase despite uncertainty, based on the short-term forecast in large cities. It is also necessary to pay attention to the future impact of increased contact opportunities due to the reactivation of socioeconomic activities on the infection status.
• Based on the estimated trends of the past two years, there is concern about earlier spread of the new coronavirus infection this winter, an earlier seasonal flu epidemic than usual, which is at a low level at this point, and that these two may occur simultaneously.

Factors that increase and suppress infection

1. [Immunity as a result of vaccination and infection]

   Immunity acquired from vaccination and natural infection may decline over time. Although the vaccination rate is higher among people in their 60s and older than those in their 20s to 40s, the acquisition of immunity by infection is lower, and there is concern about the spread of infection among elderly people.

2. [Contact patterns]

   The nighttime population is increasing in many regions. There is also a concern that the nighttime population will further increase toward the end of the year.

3. [Epidemic strain]

   In Japan, the BA.5 lineage has largely become mainstream, and is replacing others. At present, there is not a trend toward further replacement by other lineages.

4. [Climatic factors]

   Weather conditions will be favorable for ventilation for a while, but ventilation may be difficult on days with a low temperature or bad weather such as heavy rainfall.

Situation of the medical care provision system

• Nationwide, the use rate of beds is generally decreasing and the rates in all areas are at a low level below 30%. The use rate of beds for severe cases is also at a low level, but we need to watch for effects associated with an increase in the number of new cases of infection.
• In the field of nursing care, patients are being treated in the facilities and infections are seen among workers.
• Cases of problems with emergency transportation remain on the same level nationwide both for suspected non-COVID-19 cases and suspected COVID-19 cases.

Measures to be taken

Basic concepts

• To prepare for re-spreading of the novel coronavirus infection and simultaneous seasonal influenza epidemics, measures to strengthen and focus the healthcare system should be taken for 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 and strengthening and prioritization of the health care system will be promoted to protect those at high risk of aggravation, such as elderly people, and to ensure regular medical care.
• 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 vaccination
   • As for the “vaccine for the Omicron variant," vaccination of all persons aged 12 and older who have completed the first vaccination should proceed.
   • Vaccination for the BA.4 and BA.5 lineage has also started. As both vaccines for the BA.1 and for 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 vaccines that can be given sooner. As the vaccination interval from the last vaccination was shortened from 5 months to 3 months, all eligible persons will be asked to receive the vaccine for the Omicron variant during this year.
   • 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.
   • The initial vaccination for children (aged 6 months to 4 years) has been approved by the PMDA and is positioned as an extraordinary vaccination, and initial vaccination in this age group will proceed.
2. 2. Use of tests
   • Based on the recommendations of the 17th meeting of the Novel Coronavirus Subcommittee, the national and local governments are required to secure a system that enables testing, and should further utilize testing.
   • Performance of frequent tests (about 2 or 3 times a week for facility workers) for workers at facilities for elderly people.
   • Further promotion of the establishment of a system whereby patients with symptoms can self-test using an antigen qualitative test kit, and can then promptly undergo health observation at a health follow-up center, etc. if the result is positive.
   • Further promotion of the utilization of antigen qualitative test kits that are switched to OTC and are sold on the internet.
3. 3. Securing a medical care provision system

   Prefectural governments must take measures to avoid overcrowding of beds and fever outpatient clinics with the support of the national government.

   • 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
   • Making appropriate adjustments so that patients requiring inpatient treatment can be hospitalized preferentially, performing frequent tests at facilities for elderly people, etc., and further strengthening medical support
   • 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
   • Promotion of effective and less burdensome measures against infection, such as flexible and efficient use of hospital beds through zoning of each hospital room
   • Expansion and promotion of fever outpatient services, including the use of online medical care, etc., and further promotion of the development of a “fever outpatient self-examination system”
   • Local residents should be informed that they should refrain from visiting an emergency outpatient unit only to receive a precautionary examination without symptoms, according to the actual situation in the region. In addition, in order to respond to concerns and questions at the time of worsening physical conditions, the consultation service by healthcare professionals via telephone 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
4. 4. Response to simultaneous epidemics of novel coronavirus infection and seasonal influenza
   • Assuming that there are many patients with fever during simultaneous epidemics, the following measures should be promoted according to the actual situation of each region: strengthening of fever outpatient clinics, strengthening of telephone and online examination services in preparation for cases of overcrowding at fever outpatient clinics, smooth supply of therapeutic drugs, expansion of health follow-up centers, securing of self-examination kits, and strengthening of the consultation system.
   • The prefectures will formulate plans to establish systems such as strengthening of outpatient medical care systems in accordance with the actual conditions in each region.
   • In addition, efforts will be made to provide information to the public and to call for cooperation at clinic visits/treatment according to the risk of aggravation.
   • To prevent the infection from becoming severe as far as possible when symptoms occur, vaccination against the new coronavirus and influenza virus should also be promoted among those to be vaccinated.
   • In case the number of infected persons increases extremely and hospitals are under severe strain, or changes in the characteristics of viruses increase the pathogenicity, a response depending on the situation is required, and includes requests/calls for residents and business operators to prevent spreading of the infection and to maintain the functions of medical systems, as well as highly effective measures to prevent the spread of infection including behavioral restrictions.
5. 5. Surveillance
   • The limited scope of notification of occurrence, notified items, delay in testing/diagnosis/reporting due to the many cases of the infection, changes in medical care-seeking behavior, etc. are raising concerns about deterioration of the current surveillance program’s accuracy. To understand the epidemiological status, an effective and appropriate surveillance program should be developed promptly.
     It is also necessary to continue monitoring the trends of variants through genomic surveillance.
6. 6. Effective ventilation
   • Based on the recommendations of the 17th meeting of the Novel Coronavirus Subcommittee, it is necessary to publicize and recommend effective ventilation methods to prevent insufficient indoor ventilation (how to create airflow considering aerosols, installation of partitions that do not block airflow, etc.).
7. 7. Re-inspection and implementation of basic infection control

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

   • 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.
   • Eating and drinking should be done with as few people as possible, and masks should be worn except while eating and drinking.
   • 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.
   • To reduce the chances of contact as far as possible, measures are necessary at the workplace are needed, such as and include again promoting the use of telework.
   • Organizers of events, meetings, etc., should fully evaluate the epidemic situation and risk of infection in the area, and consider whether or not to hold the gathering, and if it is held, measures should be taken to minimize the infection risk.
   • Since a 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 temperature, and take thorough measures against infection when going out. They must also be asked to avoid contact with people who are at risk of aggravation, 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 or when having contact with people, keeping contact with people to a minimum period of time, 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 mucosa, aerosol inhalation, contact infection, etc.).

3. [Severity]

   It has been suggested that infection with the Omicron variant presents a lower risk of hospitalization or aggravation than the Delta variant. However, analyses to date show that the fatality due to infection with the Omicron variant is higher than that due to seasonal influenza. It is also suggested that the incidence of pneumonia is higher than that of seasonal influenza, but given the limited data, it needs to be investigated by various analyses.

   In the death toll from the previous outbreak compared to last summer‘s outbreak, it is reported that there are many cases in which the new coronavirus infection is not the direct cause of death, for example, people who have been in a facility for the elderly before the infection are infected and die due to the worsening of the underlying disease. In the current spread of infection, the rate of severe cases has continued to decrease and the ratio of elderly people among hospitalized patients has increased compared to the previous summer, following the previous outbreak. Among the deaths in this outbreak, mechanical ventilation/nasal high flow use rates and steroid prescription rates have decreased compared to the previous outbreak.

   Among fatal cases in which endogenous death was identified in infected children, cases without underlying diseases were also found. Preliminary 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 other than respiratory symptoms such as vomiting and poor oral intake.

4. [Virus shedding period]

   According to Japanese data, risk of infection remains until 10 days after onset, and infectivity is high until 7 days after onset. Even after waiting for 5 days, 1/3 of patients are still shedding infectious viruses. On Day 8 (after waiting 7 days), most patients (approximately 85%) had not shed infectious virus, and it was reported that even in those who shed the virus, the amount of virus decreased to one-sixth after 7 days compared to the initial stage.

5. [Vaccine effect]

   For infection with the Omicron variant, the preventive effects of a first vaccination against infection and disease onset are markedly reduced. Its preventive effect on hospitalization is reported to be 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 effect, onset-preventing effect, and hospitalization-preventing effect against infection by the Omicron variant, and information on how these vaccine effects are attenuated after a third vaccination has become available. Regarding the fourth vaccination, it has been reported that while the preventive effect against aggravation was not reduced for 6 weeks, the preventive effect against infection lasted only for a short time.

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 which have 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 and BQ.1.1 lineages (sublineages of the BA.5.3 lineage), which are frequently reported in Europe and the United States, as well as the XBB lineage (recombinant of the BJ.1 lineage [sublineages of the BA.2.10 lineage] and the BM.1.1.1 lineage [sublineages of the BA.2.75.3 lineage]), which has been reported mainly in India and Singapore. In particular, in the United States, there is concern that the proportion of the BQ.1 and BQ.1.1 lineages will increase in the future. However, no clear findings of infectivity and severity, etc. of these variants have been obtained. It is necessary to continue to collect 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)