115th Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (January 25, 2023) Material 1
* 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 24, 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 time of writing this document on Jan 24.
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 as a result of vaccination. However, immunity acquired both through vaccination and natural infection is considered to decrease over time, and it may have already declined in elderly people.
The nighttime population nationwide decreased during the year-end and New Year holidays, and then a continuous increasing trend has been seen in many regions.
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 has 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.
With a full-fledged winter, temperatures are dropping nationwide, and ventilation may be difficult. Respiratory virus infections also tend to be prevalent in winter.
In winter, it is also the time when the number of patients with diseases other than 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.
Re-inspection and implementation of the following basic infection control measures are needed.
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.
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.).
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.
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.
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.
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)
114th Meeting of the COVID-19 Advisory Board of the Ministry of Health, Labour and Welfare (January 17, 2023) Material 1
* 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.
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.
As in previous years, the nighttime population decreased nationwide during the year-end and New Year holidays and then increased again.
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.
With a full-fledged winter, temperatures are dropping nationwide, and ventilation may be difficult. Respiratory virus infections also tend to be prevalent in winter.
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.
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.
Re-inspection and implementation of the following basic infection control measures are needed.
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.
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.).
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.
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.
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.
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
* 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.
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.
As in usual years, the nighttime population decreases greatly during the year-end and New Year holidays in most areas including large cities.
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.
With a full-fledged winter, temperatures are lowering nationwide, and ventilation may be difficult. Respiratory virus infections also tend to be prevalent in winter.
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.
Re-inspection and implementation of the following basic infection control measures are needed.
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.
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.).
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.
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.
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.
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
*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.
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.
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.
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.
As winter is approaching and temperatures are dropping nationwide, ventilation may be difficult. In addition, respiratory virus infections tend to be prevalent in winter.
Prefectural governments must take measures to avoid overcrowding of beds and fever outpatient sections with the support of the national government.
Re-inspection and implementation of the following basic infection control measures are needed.
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.
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.).
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.
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.
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.
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
* 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.
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.
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.
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.
Temperatures are dropping nationwide including northern Japan, and ventilation may be difficult. In addition, respiratory virus infections tend to be prevalent in winter.
Prefectural governments must take measures to avoid overcrowding of beds and fever outpatient sections with the support of the national government.
Re-inspection and implementation of the following basic infection control measures are needed.
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.
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.).
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.
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.
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.
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
* 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.
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.
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.
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.
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.
Prefectural governments must take measures to avoid overcrowding of beds and fever outpatient clinics with the support of the national government.
Re-inspection and implementation of the following basic infection control measures are needed.
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.
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.).
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.
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.
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.
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
* 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.
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.
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.
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.
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.
Prefectural governments must take measures to avoid overcrowding of beds and fever outpatient clinics with the support of the national government.
Re-inspection and implementation of the following basic infection control measures are needed.
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.
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.).
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.
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.
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.
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
* 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.
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 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.
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.
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.
Re-inspection and implementation of the following basic infection control measures are needed.
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.
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.).
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.
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.
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.
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
* 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.
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.
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.
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.
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.
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.
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.).
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.
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.
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.
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
* 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.
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%.
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.
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.
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.
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.
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.
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%.
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.
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.
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.
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.
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.
Prefectural governments must take measures to avoid overcrowding of beds and fever outpatient clinics with the support of the national government.
Re-inspection and implementation of the following basic infection control measures are necessary.
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.
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.).
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.
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.
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.
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)
Published: October 26, 2022
Center for Field Epidemic Intelligence, Research and Professional Development,
National Institute of Infectious Diseases
Center for Surveillance, Immunization, and Epidemiologic Research,
National Institute of Infectious Diseases
We would like to express our deepest condolences to the bereaved families of all those who have passed away after SARS-CoV-2 infection.
Background and objectives
The Ministry of Health, Labour, and Welfare (MHLW) requested local public health authorities to conduct genome analysis of severe and fatal cases of SARS-CoV-2 infection to accumulate and monitor knowledge on the severity of SARS-CoV-2 infection on the basis of “the enhanced field epidemiological investigation requested for conducting genome analysis and variant screening by real-time polymerase chain reaction (PCR) tests for SARS-CoV-2 (Administrative notice #0205-4 from the Director of Tuberculosis and Infectious Disease Control Division, Health Serviced Bureau of MHLW on February 5, 2021; partially revised on February 10, 2022)” and “Regarding the handling of hospital admissions and discharges, close contacts, and disclosure of patients with confirmed infection by the B.1.1.529 lineage (Omicron variant) (Administrative notice from MHLW on February 2, 2021)” promulgated by Article 15, the Act on the Prevention of Infectious Diseases and Medical Care for Patients with Infectious Diseases (Act No. 114 of October 2, 1998).
Recently, the MHLW and the National Institute of Infectious Diseases (NIID) have been concerned about the severe or fatal pediatric cases of SARS-CoV-2 infection as the number of pediatric cases increased 1), so we conducted an epidemiological investigation of fatal cases of SARS-CoV-2 infection in patients under 20 years old (fatal pediatric cases). Fatal pediatric cases included those caused both directly and indirectly by SARS-CoV-2 infection. We collaborated with three academic societies: the Japan Pediatric Society, the Japanese Society of Intensive Care Medicine, and the Japanese Association for Acute Medicine.
This record is an interim analysis of the fatal pediatric cases reported from January 1 to August 31, 2022.
Methods
Subjects who satisfied either of the following two conditions were included in the investigation. Research staff or fellows of the Field Epidemiology Training Program for NIID collected epidemiological data of local health authorities and visited medical institutions to collect data on medical records if possible and interview physicians (hereafter, field investigation).
Subjects investigated
1)Patients under 20 years old whose date of onset (or admission date) was on January 1, 2022, or later, and who died during the acute phase of infection with SARS-CoV-2.
2)Patients under 20 years old whose date of onset (or admission date) was on January 1, 2022, or later, and who died after the acute phase of infection with SARS-CoV-2 (including cases with other causes of death).
Items investigated
Age, sex, underlying disease, vaccine history of SARS-CoV-2 immunization, date of onset, date of death, symptoms/findings, disease suspected of causing death, and others.
Results (Interim)
A summary of the cases and results of the field investigation as of August 31, 2022, follows below. In collecting the information on the cases, it was difficult to classify the subjects into those exactly meeting criterion 1) or 2). Moreover, we have taken care to ensure that individuals are not identifiable.
〇 Summary of the cases
The total number of cases was 41 (age: <1 year old, n=8 [20%]; 1–4 years old, n=10 [24%]; 5–10 years old, n=17 [41%]; 12–19 years old, n=5 [12%]; and unknown, n=1 [2%]; sex: males, 23 cases [56%] and females, 18 cases [44%]). The figure shows the distribution of cases based on the date of onset after January 1, 2022 (epidemiological week 52, 2021). Cases have been continuously reported since January 2022 and started to increase from epidemiological week 28 (July 11–July 17).
Figure. Reported number of deaths in patients under 20 years of age after SARS-CoV-2 infection (n=34*; date of onset or admission date from January 1, 2022 [week 52, 2021] to August 31, 2022 [week 35, 2022]) (as of August 31, 2022**)
* Seven cases were excluded for unknown date of onset.
** Case numbers in late August may not reflect the actual number of cases due to delayed reporting, so care must be taken in interpreting the data.
〇 Results of the field investigation
Of the 41 cases, we could conduct a field investigation of 32 cases. Among them, 29 cases were considered to be endogenous deaths (death due to other than trauma). The details of these 29 cases are as follows (Table).
Among the 29 cases, eight (28%) patients were <1 year old, six (21%) were 1–4 years old, 12 were 5–11 years old, and three (10%) were 12–19 years old, of whom 16 cases (55%) were in males and 13 cases (45%) were in females. Underlying disease was present in 14 (48%) patients and absent in 15 (52%). As of August 31, 2022, details of underlying disease, including duplicates, showed seven with central nervous system (CNS) abnormalities (50%), two with congenital heart disease (14%), and two with chromosomal abnormalities (14%). Among these 29 patients, 14 (48%) were not eligible for SARS-CoV-2 immunization and 15 (52%) were. Among the 15 patients eligible for SARS-CoV-2 immunization who were 5 years old or older, 13 (87%) were not vaccinated, and two (13%) were vaccinated twice, both of whom were 12 years old or older and whose last vaccination had been more than three months earlier. Moreover, a high number of symptoms or clinical findings on hospital arrival included fever in 23 cases (79%), nausea and/or vomiting in 15 (52%), disturbance of consciousness in 13 (45%), cough in nine (31%), inadequate intake of nutrition in nine (31%), seizure in eight (28%), and dyspnea in seven (24%). The main diseases suspected of causing death in medical institutions included cardiac abnormalities (n=7, 24%: myocarditis, arrhythmia, etc.), CNS abnormalities (n=7, 24%: acute encephalopathy, etc.), respiratory abnormalities (n=3, 10%: pneumonia, bacterial pneumonia, etc.), other diseases (n=6, 21%: multiple organ failure, etc.), and unknown cause of death (n=6, 21%). Several patients with a more rapid disease progression died due to CNS abnormalities such as encephalopathy, etc., and cardiac abnormalities such as myocarditis or arrhythmia. The date of onset was determined in 26 of the 29 cases, and the number of days from onset to death was a median of four days (range: 0–74 days), with eight patients (31%) dying in 0–2 days, 11 dying (42%) in 3–6 days, and seven dying (27%) in 7 days or more.
Of the 29 cases, 14 were thought to have underlying disease, including eight cases (57%) in patients under 5 years old (including four under one year old) and six cases (43%) in patients 6 years old or older. Nine cases (64%) were in males and five cases (36%) were in females. Symptoms or clinical findings on hospital arrival included fever in 11 cases (79%), dyspnea in seven (50%), nausea and/or vomiting in six (43%), cough in five (36%), inadequate intake of nutrition in four (29%), seizure in three (21%), and disturbance of consciousness in three cases (21%). In the medical institutions, the main diseases suspected of causing death were cardiac abnormality (n=3, 21%), respiratory abnormality (n=3, 21%), CNS abnormality (n=2, 14%), other disease (n=3, 21%), and unknown disease (n=3, 21%). Among these 14 cases, date of onset could be obtained in 12, and the number of days from onset to death was a median of four days (range: 1–74 days), with three patients (25%) dying in 0–3 days, seven dying (58%) in 3–6 days, and two dying (17%) in 7 days or more.
Of the 29 cases, 15 were considered to have no underlying disease. These included six cases (40%) in patients under five years old (including four under one year old) and nine cases (60%) in patients over 5 years old. Seven cases (47%) were in males and eight cases (53%) were in females. Symptoms or clinical findings on hospital arrival included fever in 12 cases (80%), disturbance of consciousness in 10 (67%), nausea and/or vomiting in nine (60%), seizure in five (33%), inadequate intake of nutrition in five (33%), cough in four (27%), and no cases (0%) with dyspnea. In the medical institutions, the main diseases suspected of causing death were CNS abnormalities (n=5, 33%), cardiac abnormalities (n=4, 27%), other disease (n=3, 20%), unknown cause of death (n=3, 20%), and respiratory abnormalities (n=0, 0%). Date of onset was obtained in 14 of the 15 cases, and the number of days from onset to death was a median of 4.5 days (range: 0–15 days), with five patients (36%) dying in 0–2 days, four dying (29%) in 3–6 days, and five dying (36%) in 7 days or more.
Table. Characteristics of fatal cases under 20 years of age after SARS-CoV-2 infection (n=29; limited to clearly endogenous deaths occurring only from January 1 to August 31, 2022; as of August 31, 2022)
* Three cases whose date of onset or death was uncertain were excluded. Included were 12 cases with underlying disease and 14 cases without underlying disease.
Discussion
As of August 31, 2022, we described the interim report on 41 fatal pediatric cases from January 1 to August 31, 2022.
The number of cases had increased from mid-July 2022. In this field investigation, fatal pediatric cases caused by clearly endogenous factors included those in patients not only with underlying disease but also in patients with no underlying disease. Thus, families and healthcare workers might need to carefully follow the course of symptoms in those after SARS-CoV-2 infection. SARS-CoV-2 immunization was not administered in many of the fatal pediatric cases even though the children were of an approved age for the immunization. Moreover, compared to the registry of Japanese children with COVID-19 done by the Japan Pediatrics Society 2), the symptoms of the fatal pediatric cases in this investigation, except for respiratory symptoms, included a high proportion of nausea and/or vomiting (52%), disturbance of consciousness (45%), inadequate intake of nutrition (31%), and seizure (28%). The severity of COVID-19 is mainly classified only according to respiratory symptoms 3), but our results suggested that pediatric cases should be carefully followed up not only for respiratory symptoms but also for symptoms of CNS abnormalities such as disturbance of consciousness and seizure, vomiting, and inadequate intake of nutrients. The duration from onset to death was under one week in 73% of the patients, and our results further suggested that careful follow-up of the cases was important especially for the first week after onset of the disease.
Limitations and further investigation
This was an interim report as of August 31, 2022, and as the field investigation will continue to collect additional information on the fatal pediatric cases, the report may be revised and/or further information may be added, and we did not examine the causal relationship between SARS-CoV-2 infection and death. Therefore, the results should be carefully interpreted.We plan to continue to investigate fatal pediatric cases in cooperation with the local public health authorities and related academic associations.
Collaborating academic associations
Japan Pediatric Society, The Japanese Society of Intensive Care Medicine, Japanese Association for Acute Medicine.
References
1. Ministry of Health, Labour, and Welfare. Visualizing the data: information on COVID-19 infections. https://covid19.mhlw.go.jp/en/ (accessed on August 19, 2022).
2. Committee on Immunization and Prevention of Infectious Diseases, Japan Pediatric Society. Interim Report on Clinical Course of Domestic-Onset Pediatric Coronavirus Disease 2019 (COVID-19) Cases Using a Database: 3rd Report. Changes in Clinical Symptoms and Severity of Pediatric COVID-19 Cases Associated with the Omicron Epidemic. http://www.jpeds.or.jp/uploads/files/20220328_tyukan_hokoku3.pdf (accessed on August 19, 2022) [in Japanese].
3. Medical Treatment Guidance Review Committee. COVID-19 Treatment guidelines, the 8th Edition. https://www.mhlw.go.jp/content/000967699.pdf (accessed on August 19, 2022) [in Japanese].