82th meeting of the COVID-19 advisory boardof Ministry of Health, Labour and Welfare (April 27, 2022). Material 1
Effective reproduction number: On a national basis, the most recent number is below 1 at 0.97 (as of April 10). The figure stands at 0.94 in the Tokyo metropolitan area and 0.97 in the Kansai area.
* The value for new cases of infection is the number of persons per 100,000 among the total number for the latest week, based on reporting dates.
The number of new cases of infection is approximately 353 (approximately 392 in Sapporo City), with a ratio to the previous week of more than 1 (1.12). The individuals are mainly in their 20s or younger. The number of those in their teens or younger is particularly increasing. The use rate of beds is slightly more than 10%.
In Ibaraki, the number of new cases of infection is approximately 197, with a ratio to the previous week of less than 1 (0.81). The individuals are mainly in their 20s or younger. The number increased in teens. The use rate of beds is slightly more than 10%. In Gunma, the number of new cases of infection was approximately 169, with a ratio of this week to last week of 1.0. In Tochigi it was approximately 239, with a ratio of this week to last week of more than 1.0 (1.13). The use rate of beds is slightly less than 20% in Tochigi and slightly more than 30% in Gunma.
In Tokyo, the number of new cases of infection is approximately 266, with a ratio of this week to last week of less than 1 (0.84). The individuals are mainly in their 20s or younger. It decreased in all age groups. The use rate of beds is slightly more than 20%, while the use rate of beds for severe cases is roughly 20%. In Saitama, Chiba, and Kanagawa, the numbers of new cases of infection are approximately 221, 196, and 211, respectively, with a ratio of this week to last week of less than 1 (0.87, 0.84, and 0.79, respectively). The use rates of beds are slightly more than 20% in Saitama, slightly more than 10% in Chiba, and slightly more than 20% in Kanagawa.
In Aichi, the number of new cases of infection is approximately 208, with a ratio of this week to last week of less than 1 (0.96). The individuals are mainly in their 20s or younger. The use rate of beds is slightly more than 20%. In Gifu, Shizuoka and Mie, the ratio of this week to last week was less than 1 (0.98, 0.90, and 0.83, respectively), with the number of new cases of infection at approximately 201, 143 and 183. The use rates of beds are slightly more than 20% in Gifu, slightly more than 10% in Shizuoka, and approximately 20% in Mie.
In Osaka, the number of new cases of infection is approximately 239, with a ratio of this week to last week of less than 1 (0.87). The individuals are mainly in their 20s or younger. It has slightly decreased or decreased in all age groups. The use rate of beds is slightly more than 20%, and the use rate of beds for severe patients is slightly less than 20%. In Shiga, Hyogo, Nara, and Wakayama, the numbers of new cases of infection are 168, 193, 139, and 176, respectively, with a ratio of this week to last week of less than 1 (0.79, 0.80, 0.68, and 0.83). In Kyoto, the number of new cases of infection is approximately 229, with a ratio of this week to last week of 1.0. The use rates of beds are slightly more than 20% in Shiga and Hyogo, slightly less than 20% in Kyoto, slightly more than 10% in Nara, and slightly more than 30% in Wakayama.
In Fukuoka, the number of new cases of infection is approximately 307, with a ratio of this week to last week of less than 1 (0.98). The individuals are mainly in their 20s or younger. It tends to increase in teens or younger, and decreases in other age groups. The use rate of beds is slightly less than 30%. In Saga, Kumamoto, and Miyazaki, the numbers of new cases of infection are approximately 397, 240, and 289, respectively, with a ratio to the previous week of less than 1 (0.95, 0.96, and 0.76). In Nagasaki, Oita, and Kagoshima, the numbers of new cases of infection are approximately 263, 238, and 343, respectively, with a ratio of this week to last week of more than 1 (1.17, 1.07, and 1.21). The use rates of beds are approximately 30% in Saga, slightly more than 20% in Nagasaki, Oita, and Miyazaki, slightly less than 30% in Kumamoto, and approximately 40% in Kagoshima.
The number of new cases of infection is the highest nationwide, at approximately 644, with a ratio of this week to last week of 1.0. The infected individuals are mainly in their 30s or younger. In particular, the increase among those in their teens or younger is marked. On the other hand, it decreased in those in their 80s and older. The use rate of beds is slightly less than 50%.
In Aomori, Iwate, Miyagi, Akita, Fukushima, Niigata, Ishikawa, Yamanashi, Nagano, Okayama, Hiroshima, Yamaguchi, Kagawa, and Ehime, the numbers of new cases of infection are approximately 215, 195, 171, 191, 213, 158, 193, 130, 190, 221, 235, 108, 242, and 142, respectively. The use rates of beds are slightly more than 20% in Aomori, Iwate, Miyagi, Akita, Ishikawa, Nagano, Okayama, Yamaguchi, and Kagawa, slightly more than 30% in Fukushima and Yamanashi, approximately 20% in Niigata, approximately 30% in Hiroshima, and slightly less than 20% in Ehime.
Nationwide, the number of new cases of infection continues to decrease, especially in metropolitan areas, while in Hokkaido and Okinawa it continues to increase, and there are differences in the transition of infection status. By region, in Iwate, Akita, Fukushima, Shimane, Miyazaki and Kagoshima, the moving average for the latest week has exceeded the peak since the end of last year. Accordingly, attention should be paid to the spread of infection, by region.
The number of new infections by age group tends to decrease in all age groups, but the decrease is smaller and the number of new infections per population is highest in teens or younger. In the Tokyo metropolitan area, the number of newly infections continues to decrease in almost all age groups, while in Hokkaido and Okinawa, the number of newly infections continues to increase among teens or younger. In Okinawa, decreases were seen among people in their 80s and older, but numbers leveled off in people in their 60s and 70s. The infection status in the elderly should continue to be carefully monitored in other regions.
The proportion of schools as the place of infection continues to increase.
In the current infection status, the number of new cases of infections continues to decrease nationwide, mainly in metropolitan areas, but the number of new infections continues to increase in some areas, such as Hokkaido and Okinawa. Considering that the situation in all regions is still higher than the peak of last summer, and that there are many regions with repeated increases and decreases, it is necessary to continue to pay close attention to future trends.
The infection situation is affected by changes in factors such as the following, which increase or suppress infection. However, the increase in contact opportunities and replacement by the BA.2 lineage are thought to have a strong influence on the recent increase in the number of infected people. In addition, the decreasing trend now seen may be affected by the acquisition of immunity by vaccination, and by the efforts of citizens to avoid places and situations where the risk of infection is high.
The nighttime population is showing an increasing trend in more than half the country. Depending on the time of day, there are areas that are near the peak of the nighttime population at the end of last year, and areas that exceed the peak. In addition, movement and contact may increase toward Golden Week, and it is necessary to pay attention to the impact on the infection status.
It is estimated that replacement by the BA.2 lineage has progressed to about 90% nationwide, which may be a factor in the increase in the number of newly infected individuals. Overseas, replacement by the BA.2 lineage is progressing, and the number of deaths is increasing with the spread of the infection in some countries (such as the UK). Accordingly, caution is required.
The main purpose of the third vaccination is prevention of onset and aggravation. While the third vaccination is proceeding in the elderly and also in young people, it is expected that the vaccination rate will further improve as young people become targets of vaccination. It should be noted that the protective effect against the Omicron variant is lower than that against the Delta variant, and the duration is short. The infection prevention effect of the third vaccination is expected to diminish over time. In addition, the retention of immunity due to previous infections may affect trends in occurrence, by region.
As the temperature will rise day by day, it will become easier to ventilate, due to climate conditions. It is thought that a reduction of the amount of time spent indoors has a certain effect on suppressing infection; however, it should be noted that the infection spread during this period last year.
In Okinawa, the number of inpatients and the use rate of beds remain high. In addition, there are other areas where the use rate of beds exceeds 30%, and the number of home care recipients and medical treatment adjustments continues to increase.
Cases of difficult emergency transportation dropped below the peak levels of last summer, and the numbers of both suspected non-COVID-19 cases and suspected COVID-19 cases continue to decrease. However, the number increased in some regions.
It is necessary to consider effective and appropriate surveillance, in order to properly grasp trends regarding occurrences. As a system of mutant strain monitoring, genomic surveillance should be continued in order to monitor the trend regarding replacement of the BA.1 lineage with the BA.2 lineage. For severe cases, clusters, or other applicable cases, confirmation via PCR testing for mutant strains and a whole-genome analysis is required.
It is necessary to verify the step-by-step review of quarantine measures, while taking into account the status of the current epidemic situation overseas and in Japan. In particular, attention should be paid to the recent epidemic status in the East Asian region. For individuals who are found to be positive by an entrance test, a whole-genome analysis should continue to be performed, to monitor the strains that are spreading overseas.
In situations and places where infection is widespread, it is necessary to strengthen and thoroughly implement infection control measures, based on the characteristics of the Omicron variant.
The current number of new infections continues to be higher than the peak last summer. In addition, as Golden Week approaches, it will be the season when there are more opportunities for leisure activities such as travel, events, shopping, and going out. Previously, increased contact with people who are not usually met, such as at annual events, has triggered the spread of infection. Therefore, it is necessary for citizens and businesses to cooperate to maintain the decreasing trend in the number of infections, call for thorough basic measures against infection and daily health management, to prevent a resurgence in new cases of infection. It is also necessary to keep in mind health management when going to school or commuting after Golden Week.
It is important for people to receive a third vaccination as soon as possible, regardless of type, once such vaccination becomes available. People with the novel coronavirus disease may experience severe conditions even if they are young, and may also suffer from prolonged symptoms. Accordingly, it is necessary to promote vaccinations not only in the elderly, who have a risk of aggravation of symptoms, but also in younger persons, in order to protect their health.
Basic preventative measures are still effective against infection with the Omicron variant. Therefore, administrative officers, business operators, and citizens should continue to ensure the proper wearing of nonwoven masks, hand washing, ventilation, etc. The risk of infection becomes highest when the three Cs (crowded places, closed spaces, and close contact) overlap. However, even a single C should be avoided as much as possible, because the Omicron variant is highly transmissible.
Crowded or poorly ventilated places with a large number of people and loud voices, where the risk of infection is high, should be avoided. Activities with other persons should be carried out in a small group of people who usually meet each other. Eating and drinking together should be done in a small group without speaking to the extent possible, and masks should be worn at all times except while eating and drinking. Basic infection control measures should be thoroughly implemented in transit, avoiding activities with a high infection risk at the destination, and a third vaccination or a test should be received in advance when traveling or going home.
In order to protect the lives of both ourselves and our families, and at the same time, to prevent the spread of infection with the Omicron variant, it is necessary to refrain from going out if you feel a little unwell, such as a mild fever or fatigue, and to consult with a physician and undergo tests according to local government policy. In particular, caution should be exercised when meeting persons who are at a high risk of severe illness, such as the elderly.
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. Although limited data suggest that the incidence of pneumonia is higher than that of seasonal influenza, this needs to be investigated through various analyses. People aged 80 years and older account for a larger proportion of deaths in this wave of the spread of the infection than during last summer. Many of these people had resided at medical or elderly facilities before they were found to be infected. It has been reported that not a few persons have died from causes other than the novel coronavirus infection itself. In particular, some have refused highly invasive treatments, while others did not meet the definition of severe disease, due to a worsening of an underlying disease, or for other reasons. Attention should also be given to a possible increase in the number of infected individuals requiring hospitalization, as test-positive persons with an underlying disease may experience disease exacerbation due to infection, and elderly infected patients may develop other symptoms, such as heart failure and aspiration pneumonia, even in the absence of COVID-19 pneumonia.
Viral shedding in individuals infected with the Omicron variant decreases over time. In patients with symptoms, it has been shown that the possibility of viral shedding is low at 10 days after the date of onset. In patients with no symptoms, it has been shown that viral shedding does not occur 8 days after the date of diagnosis.
For infection with the Omicron variant, the preventive effect of a first vaccination against disease onset is 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 Omicron variant infection, as well as how these vaccine effects are attenuated after a third vaccination. Overseas, a fourth vaccination has been started in some countries. It is necessary to collect information on efficacy and safety, and to examine the need for a fourth vaccination in Japan, and the eligible persons, starting time, etc.
Infection by the BA.2 lineage is spreading overseas. In Japan, the influx of the Omicron variant from overseas was initially both BA.1 and BA.1.1, but then BA.1.1 came to dominate. Currently, replacement with the BA.2 lineage is progressing. Therefore, this may affect the pace of the increase (decrease) in the number of cases of infection. Analyses of the effective reproduction number, risk of domestic secondary infection, and other indices have shown that the infectivity of the BA.2 lineage is higher than that of the BA.1 lineage. The generation time in the BA.2 lineage was 15% shorter than that in the BA.1 lineage, indicating that the effective reproduction number was 26% higher. In comparing the severity of the BA.1 lineage and BA.2 lineage, some animal studies suggest that the BA.2 lineage may be more pathogenic, but it has also been reported that there is no difference in the actual risk of hospitalization or aggravation. In addition, a report from the UK indicates that there is no difference in the preventive effect of vaccination, between these two lineages. In the UK, a small number of cases of reinfection with the BA.2 lineage after infection with the BA.1 lineage have been reported, and the affected patients were reported to have mainly been unvaccinated.
The XE lineage of the Omicron variant is a recombinant of the BA.1 and BA.2 lineages of the Omicron variant. More than 1,500 cases have been confirmed since the first case in the UK in January. The WHO report indicated that the rate of increase in community-acquired infections was approximately 10% higher than that of the BA.2 lineage. One case of the XE lineage was identified from a sample collected on March 26 during quarantine. The National Institute of Infectious Diseases suggests that although there are no reports indicating large differences in infectivity or severity, information on the overseas infection status and findings regarding the characteristics of the virus should be collected and analyzed, as before, and genomic surveillance should be continued for purposes of monitoring.
Figures (Number of new infections reported etc.) (PDF)
81th meeting of the COVID-19 advisory boardof Ministry of Health, Labour and Welfare (April 20, 2022). Material 1
Effective reproduction number: On a national basis, the most recent number is above 1 (1.01 as of April 3), while the figure stands at 1.00 in the Tokyo metropolitan area and 1.01 in the Kansai area.
* The value for new cases of infection is the number of persons per 100,000 among the total number for the latest week, based on reporting dates.
The number of new cases of infection is approximately 316 (approximately 364 in Sapporo City), with a ratio to the previous week of more than 1 (1.11). The individuals are mainly in their 20s or younger. The number of those in their teens or younger is particularly increasing. The use rate of beds is slightly more than 10%.
In Ibaraki, the number of new cases of infection is approximately 242, with a ratio to the previous week of less than 1 (0.81). The individuals are mainly in their 20s or younger. It has slightly decreased or decreased in all age groups. The use rate of beds is slightly more than 10%. In Tochigi and Gunma, the numbers of new cases of infection were approximately 212 and 169, respectively, with a ratio of this week to last week of less than 1 (0.91 and 0.90). The use rates of beds are slightly less than 20% in Tochigi and approximately 30% in Gunma.
In Tokyo, the number of new cases of infection is approximately 318, with a ratio of this week to last week of less than 1 (0.84). The infected individuals are mainly in their 30s or younger. It has slightly decreased or decreased in almost all age groups. The use rate of beds and the use rate of beds for severe cases are both slightly more than 20%. In Saitama, Chiba, and Kanagawa, the numbers of new cases of infection are approximately 253, 234, and 269, respectively, with a ratio of this week to last week of less than 1 (0.77, 0.80, and 0.91, respectively). The use rates of beds are slightly more than 30% in Saitama, approximately 20% in Chiba and slightly more than 20% in Kanagawa.
In Aichi, the number of new cases of infection is approximately 218, with a ratio of this week to last week of less than 1 (0.89). The individuals are mainly in their 20s or younger. The number increased in teens or younger. The use rate of beds is slightly less than 30%. In Gifu, Shizuoka and Mie, the ratio of this week to last week was less than 1 (0.95, 0.88, and 0.92, respectively), with the number of new cases of infection at approximately 205, 158 and 220. The use rates of beds are slightly more than 30% in Gifu, slightly more than 10% in Shizuoka, and slightly more than 20% in Mie.
In Osaka, the number of new cases of infection is approximately 274, with a ratio of this week to last week of less than 1 (0.87). The infected individuals are mainly in their 30s or younger. The number increased in those less than 10 years old. The use rate of beds is approximately 30%, and the use rate of beds for severe cases is approximately 20%. In Kyoto, Nara, and Wakayama, the numbers of new cases of infection are approximately 230, 205, and 213, respectively, with a ratio of this week to last week of less than 1 (0.93, 0.91, and 0.98). In Hyogo, the number of new cases of infection was approximately 240, with a ratio of this week to last week of 1.0. In Shiga, the number of new cases of infection is approximately 212, with a ratio of this week to last week of more than 1 (1.06). The use rates of beds are slightly less than 30% in Shiga, slightly more than 20% in Kyoto, Hyogo and Nara, and approximately 30% in Wakayama.
In Fukuoka, the number of new cases of infection is approximately 314, with a ratio of this week to last week of less than 1 (0.93). The individuals are mainly in their 20s or younger. It tended to increase in patients less than 10 years old and patients in their 60s or older. The use rate of beds is approximately 30%. In Kumamoto, Oita, and Kagoshima, the numbers of new cases of infection are approximately 249, 222, and 283, respectively, with a ratio of this week to last week of less than 1 (0.97, 0.81, and 0.98). In Saga, Nagasaki, and Miyazaki, the numbers of new cases of infection are 418, 224, and 379, respectively, with a ratio of this week to last week of more than 1 (1.17, 1.12, and 1.08). The use rates of beds are slightly more than 30% in Saga, slightly more than 20% in Nagasaki, Oita, and Miyazaki, slightly less than 30% in Kumamoto, and slightly more than 40% in Kagoshima.
The number of new cases of infection is the highest nationwide, at approximately 647, with a ratio of this week to last week of more than 1 (1.07). The infected individuals are mainly in their 30s or younger. Numbers in all age groups are increasing, especially those in their teens or younger and those in their 30s. Patients in their 60s or older continue to increase. The use rate of beds is slightly more than 50%.
In Aomori, Iwate, Akita, Fukushima, Niigata, Yamanashi, Nagano, Okayama, Hiroshima, Yamaguchi, Kagawa, and Ehime, the numbers of new cases of infection are approximately 219, 193, 226, 210, 209, 139, 252, 239, 253, 116, 263, and 155, respectively. The use rates of beds are slightly more than 20% in Aomori, Iwate, Nagano, Okayama, and Kagawa, approximately 20% in Akita and Ehime, slightly less than 30% in Fukushima and Yamaguchi, slightly less than 20% in Niigata, slightly less than 40% in Yamanashi, and slightly more than 30% in Hiroshima. The use rate of beds for severe cases is approximately 20% in Ehime.
In the number of new cases of infection, the moving average for the latest week has been increasing for about 3 weeks on a national basis, but is currently decreasing with a decreasing trend mainly in metropolitan areas. However, by region, in Akita, Fukushima, Niigata, Nagano, Ehime, Miyazaki and Kagoshima, the moving average for the latest week has exceeded the peak since the end of last year. Accordingly, attention should be paid to the spread of infection, by region. In addition, while there are areas such as Hokkaido, Saga and Okinawa that continue to increase, there are differences in the transition of infection status, such as decreasing trends mainly in metropolitan areas. In Okinawa, which currently has the highest level of infection in Japan, the number of infections has been increasing since the end of March.
The number of new infections by age group tends to decrease in all age groups, but it remains flat or slightly decreased in the age groups other than the 20s, where a clear decrease is observed. In the metropolitan area, there is generally a decreasing trend in all age groups. On the other hand, in Okinawa the number of new cases of infection continues to increase in all age groups, with the increase in teens or younger is particularly marked. In addition, the number of elderly patients continues to increase, and the infection status in the elderly should be carefully monitored in other regions.
The proportion of schools as the place of infection tends to increase.
Although the current infection status is now decreasing mainly in metropolitan areas, it continues to increase in some areas such as Hokkaido, Saga and Okinawa. It remains higher than the peak of last summer, and it is necessary to continue to watch future trends.
The infection situation is affected by changes in factors such as the following, which increase or suppress infection. However, the increase in contact opportunities and replacement by the BA.2 lineage are thought to have a strong influence on the recent increase in the number of infected people. In addition, the decreasing trend now seen may be affected by the acquisition of immunity by vaccination, and by the efforts of citizens to avoid places and situations where the risk of infection is high.
The nighttime population is showing an increasing trend in more than half the country. In most of the prefectures where the moving average of the number of newly infected people in the last week exceeded the peak since the end of last year, the nighttime population shows an increasing trend. Although it tended to decrease in the Tokyo metropolitan area, it has started to increase again in the last week. Movement and contact may increase toward Golden Week, and it is necessary to pay attention to the impact on the infection status.
It is estimated that replacement by the BA.2 lineage has progressed to about 80% nationwide, which may be a factor in the increase in the number of newly infected individuals. Overseas, replacement by the BA.2 lineage is progressing, and the number of deaths is increasing with the spread of the infection in some countries (such as the UK). Accordingly, caution is required.
The main purpose of the third vaccination is prevention of onset and aggravation. While the third vaccination is proceeding in elderly people, the vaccination rate is still low in young people. However, it is expected that vaccination will proceed by becoming the targets for vaccination.
It should be noted that the protective effect against the Omicron variant is lower than that against the Delta variant, and the duration is short. The infection prevention effect of the third vaccination is expected to diminish over time. In addition, the retention of immunity due to previous infections may affect trends in occurrence, by region.
As the temperature will rise day by day, it will become easier to ventilate, due to climate conditions. It is thought that a reduction of the amount of time spent indoors has a certain effect on suppressing infection; however, it should be noted that the infection spread during this period last year.
In regions such as Saga and Okinawa where the number of new cases of infection continues to increase, the number of inpatient cases and the use rate of beds show increasing trends. In addition, the number of patients in home care or arranging accommodations for care is increasing in multiple regions, including Fukuoka, Saga, and Okinawa.
The number of cases of difficult emergency transportation was below the peak of last summer, but both suspected non-COVID-19 cases and suspected COVID-19 cases leveled off. However, the number increased in some regions.
It is necessary to consider effective and appropriate surveillance, in order to properly grasp trends regarding occurrences. As a system of mutant strain monitoring, genomic surveillance should be continued in order to monitor the trend regarding replacement of the BA.1 lineage with the BA.2 lineage. For severe cases, clusters, or other applicable cases, confirmation via PCR testing for mutant strains and a whole-genome analysis is required.
It is necessary to verify the step-by-step review of quarantine measures, while taking into account the status of the current epidemic situation overseas and in Japan. In particular, attention should be paid to the recent epidemic status in the East Asian region. For individuals who are found to be positive by an entrance test, a whole-genome analysis should continue to be performed, to monitor the strains that are spreading overseas.
In situations and places where infection is widespread, it is necessary to strengthen and thoroughly implement infection control measures, based on the characteristics of the Omicron variant.
The current number of new infections continues to be higher than the peak last summer. In addition, as Golden Week approaches, it will be the season when there are more opportunities for leisure activities such as travel, events, shopping, and going out. Previously, increased contact with people who are not usually met, such as at annual events, has triggered the spread of infection. Therefore, it is necessary for citizens and businesses to cooperate to maintain the decreasing trend in the number of infections, call for thorough basic measures against infection and daily health management, to prevent a resurgence in new cases of infection.
It is important for people to receive a third vaccination as soon as possible, regardless of type, once such vaccination becomes available. People with the novel coronavirus disease may experience severe conditions even if they are young, and may also suffer from prolonged symptoms. Accordingly, it is necessary to promote vaccinations not only in the elderly, who have a risk of aggravation of symptoms, but also in younger persons, in order to protect their health.
Basic preventative measures are still effective against infection with the Omicron variant. Therefore, administrative officers, business operators, and citizens should continue to ensure the proper wearing of nonwoven masks, hand washing, ventilation, etc. The risk of infection becomes highest when the three Cs (crowded places, closed spaces, and close contact) overlap. However, even a single C should be avoided as much as possible, because the Omicron variant is highly transmissible.
Crowded or poorly ventilated places with a large number of people and loud voices, where the risk of infection is high, should be avoided. Activities with other persons should be carried out in a small group of people who usually meet each other. In principle, eating and drinking together should be done in a small group without speaking to the extent possible, and masks should be worn at all times except while eating and drinking.
In order to protect the lives of both ourselves and our families, and at the same time, to prevent the spread of infection with the Omicron variant, it is necessary to refrain from going out if you feel a little unwell, such as a mild fever or fatigue, and to consult with a physician and undergo tests according to local government policy. In particular, caution should be exercised when meeting persons who are at a high risk of severe illness, such as the elderly.
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. Although limited data suggest that the incidence of pneumonia is higher than that of seasonal influenza, this needs to be investigated through various analyses. People aged 80 years and older account for a larger proportion of deaths in this wave of the spread of the infection than during last summer. Many of these people had resided at medical or elderly facilities before they were found to be infected. It has been reported that not a few persons have died from causes other than the novel coronavirus infection itself. In particular, some have refused highly invasive treatments, while others did not meet the definition of severe disease, due to a worsening of an underlying disease, or for other reasons. Attention should also be given to a possible increase in the number of infected individuals requiring hospitalization, as test-positive persons with an underlying disease may experience disease exacerbation due to infection, and elderly infected patients may develop other symptoms, such as heart failure and aspiration pneumonia, even in the absence of COVID-19 pneumonia.
Viral shedding in individuals infected with the Omicron variant decreases over time. In patients with symptoms, it has been shown that the possibility of viral shedding is low at 10 days after the date of onset. In patients with no symptoms, it has been shown that viral shedding does not occur 8 days after the date of diagnosis.
For infection with the Omicron variant, the preventive effect of a first vaccination against disease onset is 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 Omicron variant infection, as well as how these vaccine effects are attenuated after a third vaccination. Overseas, a fourth vaccination has been started in some countries. It is necessary to collect information on efficacy and safety, and to examine the need for a fourth vaccination in Japan, and the eligible persons, starting time, etc.
Infection by the BA.2 lineage is spreading overseas. In Japan, both the BA.1 lineage and the BA.1.1 lineage of the Omicron variant initially entered from overseas, after which the BA.1.1 lineage became the majority strain, and is still dominant. However, the BA.2 lineage has begun to be detected at quarantine stations and other domestic facilities, and replacement with the BA.2 lineage is progressing. Therefore, this may affect the pace of the increase (decrease) in the number of cases of infection. Analyses of the effective reproduction number, risk of domestic secondary infection, and other indices have shown that the infectivity of the BA.2 lineage is higher than that of the BA.1 lineage. The generation time in the BA.2 lineage was 15% shorter than that in the BA.1 lineage, indicating that the effective reproduction number was 26% higher. In comparing the severity of the BA.1 lineage and BA.2 lineage, some animal studies suggest that the BA.2 lineage may be more pathogenic, but it has also been reported that there is no difference in the actual risk of hospitalization or aggravation. In addition, a report from the UK indicates that there is no difference in the preventive effect of vaccination, between these two lineages. In the UK, a small number of cases of reinfection with the BA.2 lineage after infection with the BA.1 lineage have been reported, and the affected patients were reported to have mainly been unvaccinated.
The XE lineage of the Omicron variant is a recombinant of the BA.1 and BA.2 lineages of the Omicron variant. More than 1,500 cases have been confirmed since the first case in the UK in January. The WHO report indicated that the rate of increase in community-acquired infections was approximately 10% higher than that of the BA.2 lineage. One case of the XE lineage was identified from a sample collected on March 26 during quarantine. The National Institute of Infectious Diseases suggests that although there are no reports indicating large differences in infectivity or severity, information on the overseas infection status and findings regarding the characteristics of the virus should be collected and analyzed, as before, and genomic surveillance should be continued for purposes of monitoring.
Figures (Number of new infections reported etc.) (PDF)
80th meeting of the COVID-19 advisory boardof Ministry of Health, Labour and Welfare (April 13, 2022). Material 1
Effective reproduction number: On a national basis, the most recent number is greater than 1 (1.03, as of March 27), while the figure stands at 1.02 in both the Tokyo metropolitan and Kansai areas.
* The value for new cases of infection is the number of persons per 100,000 among the total number for the latest week, based on reporting dates.
The number of new cases of infection is approximately 283 (approximately 351 in Sapporo City), with a ratio to that for the previous week of more than 1 (1.13). The infected individuals are mainly in their 20s or younger. Numbers in all age groups are increasing; however, those in their 40s or younger have increased particularly markedly. The use rate of beds is slightly more than 10%.
In Ibaraki, the number of new cases of infection is approximately 299, with a ratio to that for the previous week of less than 1 (0.98). The infected individuals are mainly in their 20s or younger. The use rate of beds is approximately 20%. In Gunma, the number of new cases of infection is approximately 187, with a ratio to that for the previous week of less than 1 (0.91). In Tochigi, the number of new cases of infection is approximately 233, with a ratio to that for the previous week of more than 1 (1.02). The use rate of beds is slightly more than 20% in Tochigi and approximately 30% in Gunma.
In Tokyo, the number of new cases of infection is approximately 378, with a ratio to that for the previous week of more than 1 (1.01). The infected individuals are mainly in their 30s or younger. Numbers in all age groups are increasing; however, those under the age of 10, and those in their 20s and 30s have increased particularly markedly. The use rate of beds and the use rate of beds for severe cases are both slightly more than 20%. In Kanagawa, the number of new cases of infection is approximately 295, with a ratio to that for the previous week of more than 1 (1.02). In Saitama and Chiba, the numbers of new cases of infection are approximately 329 and 292, respectively, with a ratio to the previous week of less than 1 (0.98 and 0.97). The use rate of beds is slightly more than 30% in Saitama, slightly more than 20% in Chiba, and slightly less than 30% in Kanagawa.
In Aichi, the number of new cases of infection is approximately 244, with a ratio to that for the previous week of more than 1 (1.05). The infected individuals are mainly in their 20s or younger. Numbers in all age groups are increasing; however, those under the age of 10, and those in their 20s and 30s have increased particularly markedly. The use rate of beds is slightly more than 20%. In Gifu and Mie, the numbers of new cases of infection are approximately 215 and 241, respectively, with a ratio to that for the previous week of more than 1 (1.14 and 1.10, respectively). In Shizuoka, the number of new cases of infection is approximately 181, with a ratio to that for the previous week of less than 1 (0.93). The use rate of beds is slightly less than 30% in Gifu, slightly more than 10% in Shizuoka, and slightly more than 20% in Mie.
In Osaka, the number of new cases of infection increased to approximately 315, with a ratio to that for the previous week of 1.12. The infected individuals are mainly in their 30s or younger. Numbers in all age groups are increasing; however, those in their 40s or younger have increased particularly markedly. The use rate of beds is slightly more than 20%, while the use rate of beds for severe cases is roughly 20%. In Hyogo, Nara, and Wakayama, the numbers of new cases of infection are approximately 241, 226, and 217, respectively, with a ratio to that for the previous week of more than 1 (1.05, 1.26, and 1.31, respectively). In Shiga and Kyoto, the numbers of new cases of infection are approximately 200 and 248, respectively, with a ratio to that for the previous week of less than 1 (0.88 and 0.99, respectively). The use rates of beds are slightly more than 20% in Shiga, Kyoto, Hyogo, and Nara, and slightly more than 30% in Wakayama. The use rate of beds for severe cases is approximately 20% in Nara.
In Fukuoka, the number of new cases of infection is approximately 337, with a ratio to that for the previous week of more than 1 (1.11). The infected individuals are mainly in their 20s or younger. Numbers in all age groups are increasing; however, those in their 10s to 40s have increased particularly markedly. The use rate of beds is slightly more than 20%. In Saga, Nagasaki, Kumamoto, Oita, and Miyazaki, the numbers of new cases of infection are 356, 200, 257, 273, and 352, respectively, with a ratio to that for the previous week of more than 1 (1.18, 1.33, 1.21, 1.13, and 1.36, respectively). In Kagoshima, the number of new cases of infection is approximately 289, with a ratio to that for the previous week of less than 1 (0.97). The use rates of beds are slightly more than 20% in Saga and Oita, slightly less than 20% in Nagasaki, slightly less than 30% in Kumamoto, approximately 20% in Miyazaki, and slightly more than 30% in Kagoshima.
The number of new cases of infection is the highest nationwide, at approximately 603, with a ratio to that for the previous week of more than 1 (1.22). The infected individuals are mainly in their 30s or younger. Numbers in all age groups are increasing; however, those in their 10s or younger, and those in their 30s and 40s have increased particularly markedly. The use rate of beds is slightly more than 40%.
In Aomori, Iwate, Akita, Fukushima, Niigata, Yamanashi, Nagano, Okayama, Hiroshima, Kagawa, and Ehime, the numbers of new cases of infection are approximately 278, 198, 227, 225, 240, 200, 233, 222, 272, 228, and 160, respectively. The use rates of beds are slightly more than 20% in Aomori, Akita, Nagano, Okayama, and Ehime, approximately 30% in Iwate and Yamanashi, slightly more than 30% in Fukushima, slightly less than 20% in Niigata, slightly less than 30% in Hiroshima, and approximately 20% in Kagawa. The use rate of beds for severe cases is approximately 20% in Ehime.
Regarding the number of new cases of infection nationwide, the moving average for the latest week has been increasing for more than two weeks. Looking at the data by region, although there are regions that are showing a continuous increase, some regions have leveled off. Furthermore, since the end of last year, while some regions have now decreased to levels below the peak of the spread of the infection, in other regions, the numbers have started to rise without a substantial decrease from the peak, and there are differences in changes in the infection status. Particularly in Iwate, Akita, Fukushima, Niigata, Nagano, Ehime, Oita, Miyazaki, and Kagoshima, the moving average for the latest week has exceeded the peak in the spread of the infection from the end of last year, and the ratio to that for the previous week was 1.5 in Iwate. Accordingly, attention should be paid to the spread of infection, by region. In Okinawa, which currently has the highest level of infection in Japan, the number of infections has been increasing since the end of March.
The number of newly infected persons by age group has shown a decreasing trend in people in their 10s or younger, while numbers in those in their 50s and older are increasing. However, the number of new cases of infection has increased in all age groups, not only in metropolitan areas such as Tokyo, Aichi, and Osaka, but also in Hokkaido, Niigata, and Okinawa. In particular, the number of infections has increased remarkably in the elderly in Okinawa, and the infection status in the elderly should also be carefully monitored in other regions.
While the proportion of restaurants as the place of infection is on a decreasing trend among people in their 20s, the rate of infections in workplaces is approximately 6%, showing an upward trend (roughly 3% for all ages).
As for the current infection status, while the pace of the spread of infection is relatively slow despite high infection levels in metropolitan areas, the infection has spread rapidly in some local cities, and attention should be paid to future trends in such areas.
The infection situation is affected by changes in factors such as the following, which increase or suppress infection. However, an increase in contact opportunities and the replacement by the BA.2 lineage are thought to have a strong influence on the current increase in the number of infected people.
The nighttime population is showing an increasing trend, especially in local cities. In particular, an increasing trend is being observed in most of the regions where the moving average for the latest week has exceeded the peak in the spread of the infection from the end of last year. Therefore, the effects of this trend on the future infection status should be monitored carefully. In addition, urban areas had been showing a continuous increasing trend, but turned to a decreasing trend in the latest week.
The replacement by the BA.2 lineage has progressed, which may be a factor in the increase in the number of newly infected individuals. In Europe, replacement by the BA.2 lineage is progressing, and the numbers of severe cases and deaths are increasing with the spread of the infection in some countries (such as the UK). Accordingly, caution is required.
The main purpose of the third vaccination is prevention of onset and aggravation. While the third vaccination is proceeding in elderly people, the vaccination rate is still low in young people. However, it is expected that vaccination will proceed by becoming the targets for vaccination. It should be noted that the protective effect against the Omicron variant is lower than that against the Delta variant, and the duration is short. The infection prevention effect of the third vaccination is expected to diminish over time. In addition, the retention of immunity due to previous infections may affect trends in occurrence, by region.
As the temperature will rise day by day, it will become easier to ventilate, due to climate conditions. It is thought that a reduction of the amount of time spent indoors has a certain effect on suppressing infection; however, it should be noted that the infection spread during this period last year.
The use rate of beds has been decreasing continuously with the nationwide decrease in new cases of infection, although there are some differences in the situation between regions. However, the use rate of beds has recently increased in some regions, due to an increasing trend in the number of new cases of infection (e.g., Hiroshima, Kagoshima, and Okinawa). In addition, the number of patients in home care or arranging accommodations for care is increasing in multiple regions, including Tokyo and Okinawa.
Regarding cases of difficult emergency transportation, the numbers of both suspected non-COVID-19 cases and suspected COVID-19 cases are decreasing, and have dropped below the peak levels of last summer. However, the number of infections has turned to an increase, in some regions.
It is necessary to consider effective and appropriate surveillance, in order to properly grasp trends regarding occurrences. As a system of mutant strain monitoring, genomic surveillance should be continued in order to monitor the trend regarding replacement of the BA.1 lineage with the BA.2 lineage. For severe cases, clusters, or other applicable cases, confirmation via PCR testing for mutant strains and a whole-genome analysis is required.
Local governments need to further improve the testing system in preparation for re-expansion of infection by the Omicron variant.
Based on the local infection status, it is necessary to continue to work to secure the required number of beds and medical staff, and to establish home-visit medical care and online medical care systems. It is still necessary to secure a system for prompt administration of oral therapeutic drugs and neutralizing antibody drugs, for patients with a risk of developing severe disease, such as elderly patients and patients with underlying diseases. It is also necessary to establish a system that allows treatment of the underlying disease to continue even if the patient has a novel coronavirus infection.
Prompt medical care support systems must be strengthened and thoroughly implemented at facilities for the elderly. When establishing a medical care support system, it is important for medical and nursing care departments to cooperate, and proceed in consultation with local concerned parties.
Based on administrative notices such as to prioritize health observation and improve efficiency in processing notices of the occurrence of patients, a system for outsourcing or centralization at the main office shall be secured, in order to efficiently carry out public health center operations and maintain the public health center functions required in the region. In addition, in the identification and home quarantine of close contacts, it is necessary in principle to take appropriate measures against infections according to the local infection status, and taking into account the characteristics of Omicron variant and the status of the spread of infection, it is necessary to focus on the cases of infection at facilities such as medical institutions and elderly facilities. At the same time, it is important to establish an environment where people can take a break from work or school if they feel even a little unwell.
In rural areas, the number of infected people is increasing. The above-mentioned systems need to be established in all regions.
The rate of receiving a third vaccination has exceeded 80% for the elderly aged 65 years and older, and 40% overall. However, in order to minimize the number of severe and fatal cases, especially in the elderly, and to reduce patients with symptoms to the lowest possible level, it is necessary to steadily implement a third vaccination in the elderly and subjects under the age of 65, and to vaccinate as many desiring recipients as possible. From March 25, individuals from 12 to 17 years old were also subject to a third vaccination, which is being carried out as a special temporary vaccination.
It is important for local governments to promote the provision of information on vaccination. Along with vaccination of unvaccinated individuals, a third vaccination six months or more after the initial vaccination will restore vaccine effectiveness against the Omicron variant, as well. Accordingly, a third vaccination must also be steadily implemented. Vaccinated individuals have also been reported to have a lower risk of prolonged symptoms.
Vaccination of children from 5 to 11 years old is being implemented as a special temporary vaccination, and it is necessary to promote vaccination, considering that the obligation to make efforts does not apply to these children. In anticipation of preventing infections in children, it is also important for parents and the adults around them to be vaccinated.
It is necessary to verify the step-by-step review of quarantine measures, while taking into account the status of the current epidemic situation overseas and in Japan. In particular, attention should be paid to the recent epidemic status in the East Asian region. For individuals who are found to be positive by an entrance test, a whole-genome analysis should continue to be performed, to monitor the strains that are spreading overseas.
In situations and places where infection is widespread, it is necessary to strengthen and thoroughly implement infection control measures, based on the characteristics of the Omicron variant.
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. Although limited data suggest that the incidence of pneumonia is higher than that of seasonal influenza, this needs to be investigated through various analyses. People aged 80 years and older account for a larger proportion of deaths in this wave of the spread of the infection than during last summer. Many of these people had resided at medical or elderly facilities before they were found to be infected. It has been reported that not a few persons have died from causes other than the novel coronavirus infection itself. In particular, some have refused highly invasive treatments, while others did not meet the definition of severe disease, due to a worsening of an underlying disease, or for other reasons. Attention should also be given to a possible increase in the number of infected individuals requiring hospitalization, as test-positive persons with an underlying disease may experience disease exacerbation due to infection, and elderly infected patients may develop other symptoms, such as heart failure and aspiration pneumonia, even in the absence of COVID-19 pneumonia.
Viral shedding in individuals infected with the Omicron variant decreases over time. In patients with symptoms, it has been shown that the possibility of viral shedding is low at 10 days after the date of onset. In patients with no symptoms, it has been shown that viral shedding does not occur 8 days after the date of diagnosis.
For infection with the Omicron variant, the preventive effect of a first vaccination against disease onset is 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 Omicron variant infection, as well as how these vaccine effects are attenuated after a third vaccination. Overseas, a fourth vaccination has been started in some countries. It is necessary to collect information on efficacy and safety, and to examine the need for a fourth vaccination in Japan, and the eligible persons, starting time, etc.
In some areas overseas, the number of cases of infection with the BA.2 lineage is increasing. In Japan, both the BA.1 lineage and the BA.1.1 lineage of the Omicron variant initially entered from overseas, after which the BA.1.1 lineage became the majority strain, and is still dominant. However, the BA.2 lineage has begun to be detected at quarantine stations and other domestic facilities, and replacement with the BA.2 lineage is progressing. Therefore, this may affect the pace of the increase (decrease) in the number of cases of infection. Analyses of the effective reproduction number, risk of domestic secondary infection, and other indices have shown that the infectivity of the BA.2 lineage is higher than that of the BA.1 lineage. The generation time in the BA.2 lineage was 15% shorter than that in the BA.1 lineage, indicating that the effective reproduction number was 26% higher. In comparing the severity of the BA.1 lineage and BA.2 lineage, some animal studies suggest that the BA.2 lineage may be more pathogenic, but it has also been reported that there is no difference in the actual risk of hospitalization or aggravation. In addition, a report from the UK indicates that there is no difference in the preventive effect of vaccination, between these two lineages. In the UK, a small number of cases of reinfection with the BA.2 lineage after infection with the BA.1 lineage have been reported, and the affected patients were reported to have mainly been unvaccinated.
The XE lineage of the Omicron variant is a recombinant of the BA.1 and BA.2 lineages of the Omicron variant. The report of the WHO published at the end of March indicated that more than 600 cases have been confirmed since the first case in the UK in January. In the same report, the WHO indicated that the rate of increase in community-acquired infections was approximately 10% higher than that of the BA.2 lineage. One case of the XE lineage was identified from a sample collected on March 26 during quarantine. The National Institute of Infectious Diseases suggests that although there are no reports indicating large differences in infectivity or severity, information on the overseas infection status and findings regarding the characteristics of the virus should be collected and analyzed, as before, and genomic surveillance should be continued for purposes of monitoring.
Figures (Number of new infections reported etc.) (PDF)
79th meeting of the COVID-19 advisory boardof Ministry of Health, Labour and Welfare (April 6, 2022). Material 1
Effective reproduction number: On a national basis, the most recent number is below 1 at 0.97 (as of March 20). The figure stands at 0.97 in the Tokyo metropolitan area and 0.93 in the Kansai area.
* The value for new cases of infection is the number of persons per 100,000 among the total number for the latest week, based on reporting dates.
The number of new cases of infection was approximately 251 (approximately 312 in Sapporo City), with a ratio to the previous week increasing to 1.17. They are mainly in their 20s, and the number of those in their teens and 20s tended to increase. The use rate of beds is slightly more than 10%.
In Ibaraki, the number of new cases of infection increased to approximately 304, with a ratio to the previous week of 1.13. They are mainly in their 20s or younger, with those in their teens and younger particularly increasing markedly. The use rate of beds is approximately 20%. In Tochigi and Gunma, the number of new cases of infection was approximately 228 and 206, respectively, with a ratio of this week to last week of more than 1 (1.07 and 1.02). The use rate of beds is approximately 20% in Tochigi and slightly more than 30% in Gunma.
In Tokyo, the number of new cases of infection is approximately 373, with a ratio to the previous week of more than 1 (1.04). They are mainly in their 20s or younger, with the number of those in their 20s particularly increasing. The use rate of beds and the use rate of beds for severe cases are both slightly more than 20%. In Saitama, Chiba, and Kanagawa, the number of new cases of infection is approximately 336, 300, and 290, respectively, and the ratio to the previous week increased to 1.03, 1.13, and 1.05. The use rate of beds is slightly less than 40% in Saitama, slightly more than 20% in Chiba, and slightly more than 30% in Kanagawa.
In Aichi, the number of new cases of infection is approximately 232, with a ratio to the previous week of less than 1 (0.97). They are mainly in their 20s or younger, with the number of those in their 20s particularly increasing. The use rate of beds is slightly more than 20%. In Gifu, Shizuoka and Mie, the ratio of this week to last week was more than 1 (1.11, 1.15, and 1.24, respectively), with the number of new cases of infection at approximately 188, 193 and 218. The use rate of beds is slightly more than 20% in Gifu and Mie, and approximately 20% in Shizuoka.
In Osaka, the number of new cases of infection is approximately 282, with a ratio to that for the previous week of less than 1 (0.97). They are mainly in their 20s or younger, with the number of those in their 20s particularly increasing. The use rate of beds is slightly less than 30%, while the use rate of beds for severe cases is approximately 20%. In Shiga, Hyogo, and Nara, the ratio of this week to last week was less than 1 (0.82, 0.95 and 0.95, respectively), with the number of new cases of infection at approximately 228, 229 and 179. In Kyoto and Wakayama, the number of new cases of infection was 249 and 166, respectively, with a ratio of this week to last week of more than 1 (1.16 and 1.33). The use rate of beds is slightly less than 40% in Shiga, slightly more than 20% in Kyoto, Hyogo and Nara, and approximately 30% in Wakayama. The use rate of beds for severe cases is approximately 20% in Nara.
In Fukuoka, the number of new cases of infection is approximately 302, with a ratio to the previous week of more than 1 (1.13). They are mainly people in their 20s. The use rate of beds is slightly more than 20%. In Saga, Nagasaki, Kumamoto, Oita, Miyazaki, and Kagoshima, the number of new cases of infection is about 302, 151, 212, 241, 258, and 299, respectively, with the ratio to the previous week increasing to 1.28, 1.22, 1.32, 1.39, 1.68, and 1.29. The use rate of beds is slightly more than 20% in Saga and Kumamoto, slightly more than 10% in Nagasaki, slightly less than 30% in Oita, approximately 20% in Miyazaki, and slightly less than 30% in Kagoshima.
The number of new cases of infection is the highest nationwide at approximately 496, with a ratio to the previous week increasing to 1.26. The infected individuals are mainly in their 20s or younger. All age groups are increasing, but particularly those in their 20s or younger increased markedly. The use rate of beds is approximately 30%.
In Aomori, Akita, Fukushima, Ishikawa, Yamanashi, Kagawa, and Ehime, the number of new cases of infection is approximately 252, 197, 187, 169, 204, 231, and 137, respectively. The use rate of beds is approximately 30% in Aomori, slightly more than 20% in Akita and Ehime, slightly more than 30% in Fukushima, slightly more than 10% in Ishikawa, slightly less than 40% in Yamanashi, and slightly less than 30% in Kagawa. The use rate of beds for severe cases is slightly more than 30% in Ehime.
In the number of new cases of infection nationwide, the ratio to the previous week and the moving average for the latest week have been increasing for over a week. Looking at data by region, while there are regions that show continuous increase, some regions have leveled off, so attention should be paid to future trends. Since the end of last year, while some regions have decreased to levels below the peak of the spread of infection, in some regions, it has started to rise without sufficiently decreasing from the peak, and there are differences in the changes of infection status. In particular, in prefectures such as Akita, Niigata and Kagoshima, the moving average for the latest week has already exceeded the peak of the spread of infection since the end of last year, so the spread of infection in rural areas should be watched carefully.
The number of new cases of infection by age group changed to increase in all age groups, with particularly marked increases in those in their teens and 20s. It should be noted that this tendency is strong in areas with continuous increase such as Kagoshima and Okinawa, and that the number of elderly people is also increasing.
The proportion of newly infected patients in their 20s shows an increasing trend. The proportion of restaurants as the place of infection has increased to about 7% among people in their 20s (about 2% for all ages). In the elderly, infections at nursing care facilities and medical facilities are continuing to occur.
The spread of infection thus far has tended to be prevalent in young people and then spread to the elderly. Currently, the third vaccination for the elderly is in progress, but it is necessary to pay attention to the future epidemic situation.
The infection situation is affected by changes in factors such as the following that increase and suppress infection, but the increase in contact opportunities and the replacement by the BA.2 lineage are thought to have a strong influence on the current increase in the number of infected people.
The nighttime population shows a continuous increasing trend, especially in urban areas. In some regions, the nighttime population increased to near its peak at the end of last year, and has tended to decrease in the last week. On the other hand, there are few areas where the nighttime population is continuously decreasing, and it is the time when cherry blossom viewing and welcome parties are held. In particular, the increase in the nighttime population can be a factor in increasing the number of newly infected people. It is important to note that children begin a new school year, and may have more opportunities for contact at school.
The replacement by the BA.2 lineage has progressed, which may be a factor in increasing the number of newly infected individuals. In Europe, the replacement by the BA.2 lineage is progressing, and not only infected people but also severe cases and deaths are increasing in some countries (such as UK), so caution is required.
The main purpose of the third vaccination is prevention of onset and aggravation. While the third vaccination is proceeding in elderly people, the vaccination rate is still low in young people. However, it is expected that vaccination will proceed by becoming the targets for vaccination. It should be noted that the protective effect against the Omicron variant is lower than that against the Delta variant, and the duration is short. The infection prevention effect of the third vaccination is expected to diminish over time. In addition, the retention of immunity due to previous infections may affect the trends of occurrence in the region.
As the temperature rises toward spring, it will become easier to ventilate the climate conditions. It is thought that reduction of the amount of time spent indoors has a certain effect on suppressing infection, but it should be noted that infection spread during this period last year.
With the decrease in the number of newly infected people nationwide, despite regional differences the bed usage rate has continued to decline, although it has begun to increase in some regions. In addition, the numbers of home care recipients and medical treatment adjustments are also increasing in some regions.
In cases of difficult emergency transportation, although the decreasing trend has further continued in both suspected non-COVID-19 cases and suspected COVID-19 cases, they are still at the same high level as last summer's peak. Attention should be given to the balance between medical care for novel coronavirus infections and regular medical care, especially in emergency medical care.
It is necessary to consider effective and appropriate surveillance, in order to properly grasp trends regarding occurrences. As a system of mutant strain monitoring, genomic surveillance should be continued in order to monitor the trend regarding replacement of the BA.1 lineage with the BA.2 lineage. For severe cases, clusters, or other applicable cases, confirmation via PCR testing for mutant strains and a whole-genome analysis is required.
Local governments need to further improve the testing system in preparation for re-expansion of infection by the Omicron variant.
Based on the local infection status, it is necessary to continue to work to secure the required number of beds and medical staff, and to establish home-visit medical care and online medical care systems. It is still necessary to secure a system for prompt administration of oral therapeutic drugs and neutralizing antibody drugs, for patients with a risk of developing severe disease, such as elderly patients and patients with underlying diseases. It is also necessary to establish a system that allows treatment of the underlying disease to continue even if the patient has a novel coronavirus infection.
Prompt medical care support systems must be strengthened and thoroughly implemented at facilities for the elderly. When establishing a medical care support system, it is important for medical and nursing care departments to cooperate, and proceed in consultation with local concerned parties.
Based on administrative notices such as to prioritize health observation and improve efficiency in processing notices of the occurrence of patients, a system for outsourcing or centralization at the main office shall be secured, in order to efficiently carry out public health center operations and maintain the public health center functions required in the region. In addition, in the identification and home quarantine of close contacts, it is necessary in principle to take appropriate measures against infections according to the local infection status, and taking into account the characteristics of Omicron variant and the status of the spread of infection, it is necessary to focus on the cases of infection at facilities such as medical institutions and elderly facilities. At the same time, it is important to establish an environment where people can take a break from work or school if they feel even a little unwell.
In rural areas, the number of infected people is increasing. A system like that described above needs to be established in all regions.
The rate of receiving a third vaccination has exceeded 80% for the elderly aged 65 years and older, and 40% overall. However, in order to minimize the number of severe and fatal cases, especially in the elderly, while at the same time expecting decreasing trends in infection status, it is necessary to steadily implement the third vaccination to the elderly and subjects under the age of 65, and to vaccinate as many of those who desire it as possible. From March 25, individuals 12 to 17 years old were also subject to the third vaccination, which is carried out as a special temporary vaccination.
It is important for local governments to promote the provision of information on vaccination. Along with vaccination of unvaccinated individuals, a third vaccination six months or more after the initial vaccination will restore vaccine effectiveness against the Omicron variant as well, and therefore a third vaccination must also be steadily implemented. Vaccinated individuals have also been reported to have a lower risk of novel coronavirus infection sequelae.
Vaccination of children from 5 to 11 years old is being implemented as a special temporary vaccination, and it is necessary to promote vaccination taking into account that the obligation to make efforts does not apply to these children. In anticipation of preventing infections in children, it is also important for parents and the adults around them to be vaccinated.
It is necessary to verify the step-by-step review of quarantine measures, while taking into account the status of the current epidemic situation overseas and in Japan. In particular, attention should be paid to the recent epidemic status in the East Asian region. For individuals who are found to be positive by an entrance test, a whole-genome analysis should continue to be performed, to monitor the strains that are spreading overseas.
In situations and places where infection is widespread, it is necessary to strengthen and thoroughly implement infection control measures based on the characteristics of Omicron variant.
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 may present 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. Although the limited data suggest that the incidence of pneumonia is higher than that of seasonal influenza, it needs to be investigated by various analyses. People aged 80 years and older account for a larger proportion of deaths in this wave of the spread of the infection than during last summer. Many of these people had resided at medical or elderly facilities before they were found to be infected. It has been reported that not a few have died from causes other than novel coronavirus infection itself: some refused highly invasive treatments, while others did not meet the definition of severe disease, due to the worsening of an underlying disease, or other reasons. Attention should also be given to a possible increase in the number of infected individuals requiring hospitalization, as test-positive persons with an underlying disease may experience disease exacerbation due to infection, or elderly infected patients may develop other symptoms, such as heart failure and aspiration pneumonia, even in the absence of COVID-19 pneumonia.
Viral shedding in individuals infected with the Omicron variant decreases over time. In patients with symptoms, it has been shown that the possibility of viral shedding is low 10 days after the date of onset. In patients with no symptoms, it has been shown that viral shedding does not occur 8 days after the date of diagnosis.
For infection with the Omicron variant, the preventive effect of a first vaccination against disease onset is 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 Omicron variant infection, as well as how these vaccine effects are attenuated after a third vaccination. Overseas, a fourth vaccination has been started in some countries. It is necessary to collect information on efficacy and safety, and to examine the need for a fourth vaccination in Japan, and the eligible persons, starting time, etc.
In some areas overseas, the number of cases of infection with the BA.2 lineage is increasing. In Japan, both the BA.1 lineage and the BA.1.1 lineage of the Omicron variant initially entered from overseas, after which the BA.1.1 lineage became the majority strain, and is still dominant. However, the BA.2 lineage has begun to be detected at quarantine stations and other domestic facilities, and replacement with the BA.2 lineage is progressing. Therefore, this may affect the pace of the increase (decrease) in the number of cases of infection. Analyses of the effective reproduction number, risk of domestic secondary infection, and other indices have shown that the infectivity of the BA.2 lineage is higher than that of the BA.1 lineage. The generation time in the BA.2 lineage was 15% shorter than that in the BA.1 lineage, indicating that the effective reproduction number was 26% higher. In comparing the severity of the BA.1 lineage and BA.2 lineage, some animal studies suggest that the BA.2 lineage may be more pathogenic, but it has also been reported that there is no difference in the actual risk of hospitalization or aggravation. In addition, a report from the UK indicates that there is no difference in the preventive effect of vaccination, between these two lineages. In the UK, a small number of cases of reinfection with the BA.2 lineage after infection with the BA.1 lineage have been reported, and they are reported to be mainly unvaccinated.
Figures (Number of new infections reported etc.) (PDF)
78th meeting of the COVID-19 advisory boardof Ministry of Health, Labour and Welfare (March 30, 2022). Material 1
Effective reproduction number: On a national basis, the most recent number is below 1 at 0.95 (as of March 13). The figure stands at 0.95 in the Tokyo metropolitan area and 0.90 in the Kansai area.
* The value for new cases of infection is the number of persons per 100,000 among the total number for the latest week, based on reporting dates.
The number of new cases of infection increased to approximately 214 (approximately 285 in Sapporo City), with a ratio to the previous week of 1.07.
They are mainly people in their 20s. The use rate of beds is slightly more than 10%.
In Ibaraki, the number of new cases of infection is approximately 269, with a ratio to the previous week of less than 1 (0.80). The individuals are mainly in their 20s or younger. The use rate of beds is slightly less than 30%. In Tochigi and Gunma, the number of new cases of infection increased to approximately 213 and 201, respectively, with a ratio to the previous week of 1.25 and 1.04. The use rate of beds is slightly more than 20% in Tochigi and slightly less than 40% in Gunma.
In Tokyo, the number of new cases of infection increased to approximately 358, with a ratio to the previous week of 1.05. The individuals are mainly in their 20s or younger. The use rate of beds and the use rate of beds for severe cases are both slightly more than 20%. In Saitama, the number of new cases of infection increased to approximately 325, with a ratio to the previous week of 1.01. In Chiba and Kanagawa, the number of new cases of infection increased to approximately 265 and 277, respectively, with a ratio to the previous week of less than 1 (0.95 and 0.86). The use rate of beds is about 40% in Saitama, about 30% in Chiba and slightly more than 40% in Kanagawa. The use rate of beds for severe patients is approximately 20% in Kanagawa.
In Aichi, the number of new cases of infection increased to approximately 239, with a ratio to the previous week of 1.15. The individuals are mainly in their 20s or younger. The use rate of beds is approximately 30%. In Gifu and Mie, the number of new cases of infection increased to approximately 169 and 175, respectively, with a ratio to the previous week of 1.29 and 1.20. In Shizuoka, the number of new cases of infection was approximately 169, with a ratio to the previous week of less than 1 (0.93). The use rate of beds is slightly more than 20% in Gifu and Mie, and slightly less than 20% in Shizuoka.
In Osaka, the number of new cases of infection increased to approximately 291, with a ratio to the previous week of 1.08. The individuals are mainly in their 20s or younger. The use rate of beds is slightly more than 30%, while the use rate of beds for severe patients is slightly less than 30%. In Shiga, Hyogo, and Wakayama, the number of new cases of infection increased to approximately 277, 240, and 125, respectively, with a ratio to the previous week of 1.03, 1.03 and 1.14. In Kyoto and Nara, the number of new cases of infection was approximately 215 and 189, respectively, with a ratio to the previous week of less than 1 (0.99 and 0.79). The use rate of beds is slightly less than 40% in Shiga, approximately 30% in Kyoto and Hyogo, slightly more than 30% in Nara, and approximately 20% in Wakayama. The use rate of beds for severe cases is slightly more than 30% in Nara.
In Fukuoka, the number of new cases of infection increased to approximately 268, with a ratio to the previous week of 1.08. They are mainly people in their 20s. The use rate of beds is slightly less than 30%. In Saga, Nagasaki, Kumamoto, Oita, Miyazaki, and Kagoshima, the number of new cases of infection increased to about 235, 123, 161, 173, 154, and 232, respectively, with a ratio to the previous week of 1.34, 1.16, 1.02, 1.39, 1.18, and 1.71. The use rate of beds is approximately 20% in Saga, slightly more than 10% in Nagasaki, slightly more than 20% in Kumamoto and Oita, approximately 10% in Miyazaki, and slightly more than 30% in Kagoshima.
The number of new cases of infection increased to the highest nationwide (approximately 394), with a ratio to the previous week of 1.35. The newly infected individuals are mainly in their 20s or younger, and attention should be paid to an increasing trend among those in their 20s. The use rate of beds is slightly more than 20%.
In Aomori, Akita, Yamanashi, and Kagawa, the number of new cases of infection was 284, 185, 187, and 233, respectively, with a ratio to the previous week of 1.05, 1.40, 1.25, and 1.0. In Ishikawa, the number of new cases of infection was approximately 140, with a ratio to the previous week of 0.76. The use rate of beds is approximately 30% in Aomori, slightly less than 30% in Akita, slightly more than 10% in Ishikawa, slightly less than 50% in Yamanashi, and slightly more than 30% in Kagawa.
On a national basis, the number of new cases of infection has been gradually decreasing for over a month, with both the ratio to the previous week and effective reproduction number at less than 1, but the weekly moving average of the last few days has been increasing. Attention should be paid to the effect of the consecutive holidays last week on the figures, and it is necessary to continue to monitor the infection situation to see if this increasing trend will lead to a rebound.
The proportion of newly infected patients in their 20s shows an increasing trend. The proportion of restaurants as the place of infection is increasing among people in their 20s. In the elderly, infections at nursing care facilities and medical facilities are continuing to occur. In Kagoshima and Okinawa, where an increasing trend is now seen, the increase among people in their 20s is particularly remarkable.
In Tokyo, the number of newly infected people in their 20s has shifted from decreasing to bottoming out. The number of consultations on pyrexia, etc. and the number of applications of the Tokyo rules for emergency medical care have leveled off, while the number of people tested has been on a decreasing trend, but the positive rate of tests has been on an increasing trend. Attention should be paid as there may be signs of rebound.
The following changes in factors that increase and suppress infection are thought to affect the future infection status.
The nighttime population has been increasing nationwide since the priority measures were lifted, and in some areas it has shown a rapid increase or a continuous increase in the past week. It will soon be time for cherry blossom viewing, thank-you parties, welcome and farewell parties, and in particular, the increase in the nighttime population can be a factor in increasing the number of newly infected people. On the other hand, there are also regions where the nighttime population is decreasing. Attention about children is required because, although contact at school will decrease during spring break, contact opportunities will increase in other places.
The progress of replacement by the BA.2 lineage may be a factor in increasing the number of newly infected individuals. In Europe, the replacement by the BA.2 lineage is progressing, and not only infected people but also severe cases and deaths are increasing in some countries (such as UK), so caution is required.
The main purpose of the third vaccination is prevention of onset and aggravation. While the third vaccination is proceeding in elderly people, the vaccination rate is still low in young people. However, it is expected that vaccination will proceed by becoming the targets for vaccination. It should be noted that the protective effect against the Omicron variant is lower than that against the Delta variant, and the duration is short. The infection prevention effect of the third vaccination is expected to diminish over time. In addition, the retention of immunity due to previous infections may affect the trends of occurrence in the region.
As the temperature rises toward spring, it will become easier to ventilate the climate conditions. It is thought that reduction of the amount of time spent indoors has a certain effect on suppressing infection, but it should be noted that infection spread during this period last year.
With the decrease in the number of newly infected people to date nationwide, the use rate of beds and the number of patients treated at home have continued to decrease, although there are regional differences. However, there are areas where the number of patients recovering at accommodations has stopped decreasing or has leveled off.
In cases of difficult emergency transportation, although the decreasing trend continues in both suspected non-COVID-19 cases and suspected COVID-19 cases, they are still at the same high level as last summer's peak. Attention should be given to the balance between medical care for novel coronavirus infections and regular medical care, especially in emergency medical care.
It is necessary to consider effective and appropriate surveillance, in order to properly grasp trends regarding occurrences. As a system of mutant strain monitoring, genomic surveillance should be continued in order to monitor the trend regarding replacement of the BA.1 lineage with the BA.2 lineage. For severe cases, clusters, or other applicable cases, confirmation via PCR testing for mutant strains and a whole-genome analysis is required.
Based on the infection status in each area, local governments must continue to work on securing the required number of beds and healthcare professionals, securing the functions of public health centers, which are indispensable for local communities, along with support for strengthening the healthcare center system, and establishing home-visit and online medical care systems for home care recipients. It is still necessary to secure a system for prompt administration of oral therapeutic drugs and neutralizing antibody drugs, for patients with a risk of developing severe disease, such as elderly patients and patients with underlying diseases. It is also necessary to establish a system that allows treatment of the underlying disease to continue even if the patient has a novel coronavirus infection.
Implementation of efficient public health center operations are required, based on the administrative notice, such as prioritization of health observation and streamlining the handling of patient outbreak notifications.
In addition, in the identification and home quarantine on close contacts, it is necessary in principle to take appropriate measures against infections according to the local infection status, and taking into account the characteristics of Omicron variant (such as the short incubation period and interval of onset) and the status of the spread of infection, it is necessary to focus on the cases of infection at facilities such as medical institutions and elderly facilities where people at particularly high risk of severe disease are admitted. At the same time, it is important to establish an environment where people can take a break from work or school if they feel even a little unwell.
The rate of receiving a third vaccination has exceeded 80% for the elderly aged 65 years and older, and 40% overall. However, in order to minimize the number of severe and fatal cases, especially in the elderly, while at the same time expecting decreasing trends in infection status, it is necessary to steadily implement the third vaccination to the elderly and subjects under the age of 65, and to inoculate as many of those who desire it as possible. From March 25, individuals 12 to 17 years old were also subject to the third vaccination, which is carried out as a special temporary vaccination.
It is important for local governments to promote the provision of information on vaccination. Along with vaccination of unvaccinated individuals, a third vaccination six months or more after the initial vaccination will restore vaccine effectiveness against the Omicron variant as well, and therefore a third vaccination must also be steadily implemented. Vaccinated individuals have also been reported to have a lower risk of novel coronavirus infection sequelae.
Vaccination of children from 5 to 11 years old is being implemented as a special temporary vaccination, and it is necessary to promote vaccination taking into account that the obligation to make efforts does not apply to these children. In anticipation of preventing infections in children, it is also important for parents and the adults around them to be vaccinated.
Together with measures such as shortening the waiting period for immigrants from March, it is necessary to continue to verify the step-by-step review of border quarantine measures, while taking into account the status of mutant strains overseas and in Japan. In particular, attention should be paid to the recent epidemic status in the East Asian region. For individuals who are found to be positive by an entrance test, a whole-genome analysis should continue to be performed, to monitor the strains that are spreading overseas.
In situations and places where infection is widespread, it is necessary to strengthen and thoroughly implement infection control measures based on the characteristics of Omicron variant.
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 may present 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. Although the limited data suggest that the incidence of pneumonia is higher than that of seasonal influenza, it needs to be investigated by various analyses. People aged 80 years and older account for a larger proportion of deaths in this wave of the spread of the infection than during last summer. Many of these people had resided at medical or elderly facilities before they were found to be infected. It has been reported that not a few have died from causes other than novel coronavirus infection itself: some refused highly invasive treatments, while others did not meet the definition of severe disease, due to the worsening of an underlying disease, or other reasons. Attention should also be given to a possible increase in the number of infected individuals requiring hospitalization, as test-positive persons with an underlying disease may experience disease exacerbation due to infection, or elderly infected patients may develop other symptoms, such as heart failure and aspiration pneumonia, even in the absence of COVID-19 pneumonia.
Viral shedding in individuals infected with the Omicron variant decreases over time. In patients with symptoms, it has been shown that the possibility of viral shedding is low 10 days after the date of onset. In patients with no symptoms, it has been shown that viral shedding does not occur 8 days after the date of diagnosis.
For infection with the Omicron variant, the preventive effect of a first vaccination against disease onset is 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 Omicron variant infection, as well as how these vaccine effects are attenuated after a third vaccination. Overseas, a fourth vaccination has been started in some countries. It is necessary to collect information on efficacy and safety, and to examine the need for a fourth vaccination in Japan, and the eligible persons, starting time, etc.
In some areas overseas, the number of cases of infection with the BA.2 lineage is increasing. In Japan, both the BA.1 lineage and the BA.1.1 lineage of the Omicron variant initially entered from overseas, after which the BA.1.1 lineage became the majority strain, and is still dominant. However, the BA.2 lineage has begun to be detected at quarantine stations and other domestic facilities, and replacement with the BA.2 lineage is progressing. Therefore, this may affect the pace of the increase (decrease) in the number of cases of infection. Analyses of the effective reproduction number, risk of domestic secondary infection, and other indices have shown that the infectivity of the BA.2 lineage is higher than that of the BA.1 lineage. The generation time in the BA.2 lineage was 15% shorter than that in the BA.1 lineage, indicating that the effective reproduction number was 26% higher. In comparing the severity of the BA.1 lineage and BA.2 lineage, some animal studies suggest that the BA.2 lineage may be more pathogenic, but it has also been reported that there is no difference in the actual risk of hospitalization or aggravation. In addition, a report from the UK indicates that there is no difference in the preventive effect of vaccination, between these two lineages. In the UK, a small number of cases of reinfection with the BA.2 lineage after infection with the BA.1 lineage have been reported, and they are reported to be mainly unvaccinated.
Figures (Number of new infections reported etc.) (PDF)
77th meeting of the COVID-19 advisory boardof Ministry of Health, Labour and Welfare (March 23, 2022). Material 1
Effective reproduction number: On a national basis, the most recent number is below 1 at 0.96 (as of March 7). The figure stands at 0.97 in the Tokyo metropolitan area and 0.92 in the Kansai area.
* The value for new cases of infection is the number of persons per 100,000 among the total number for the latest week, based on reporting dates.
The number of new cases of infection is approximately 200 (approximately 266 in Sapporo City), with a ratio to that for the previous week of less than 1 (0.95). They are mainly people in their 20s. The use rate of beds is approximately 20%.
In Ibaraki, the number of new cases of infection is approximately 338, with a ratio to that for the previous week of less than 1 (0.98). The infected individuals are mainly in their 20s or younger. The use rate of beds is approximately 30%. In Tochigi and Gunma, the number of new cases of infection was approximately 170 and 193, respectively, with a ratio of this week to last week of less than 1 (0.90 and 0.88). The use rate of beds is slightly more than 20% in Tochigi and approximately 40% in Gunma.
In Tokyo, the number of new cases of infection is the highest in Japan (approximately 341); however, its ratio to that for the previous week is less than 1 (0.81). The infected individuals are mainly in their 20s or younger. The use rate of beds is slightly more than 30%, and the use rate of beds for severe cases is about 30%. In Saitama, Chiba, and Kanagawa, the number of new cases of infection is approximately 322, 280, and 322, respectively, with a ratio to that for the previous week of less than 1 (0.91, 0.81, and 0.76, respectively). The use rate of beds is approximately 40% in Saitama, slightly more than 30% in Chiba and slightly more than 40% in Kanagawa. The use rate of beds for severe cases is slightly more than 20% in Kanagawa.
In Aichi, the number of new cases of infection is approximately 207, with a ratio to that for the previous week of less than 1 (0.72). The infected individuals are mainly in their 20s or younger. The use rate of beds is approximately 40%. In Gifu, Shizuoka and Mie, the ratio of this week to last week was less than 1 (0.73, 0.81, and 0.76, respectively), with the number of new cases of infection at approximately 131, 181 and 146. The use rate of beds is slightly more than 30% in Gifu, slightly more than 20% in Shizuoka, and slightly less than 30% in Mie.
In Osaka, the number of new cases of infection is approximately 269, with a ratio to that for the previous week of less than 1 (0.66). The infected individuals are mainly in their 20s or younger. The use rate of beds is approximately 50%, and the use rate of beds for severe cases is approximately 40%. In Shiga, Kyoto, Hyogo, Nara, and Wakayama, the number of new cases of infection was 270, 217, 233, 239, and 109, respectively, with a ratio of this week to last week of less than 1 (0.75, 0.73, 0.71, 0.64, and 0.75). The use rate of beds is approximately 50% in Shiga, slightly more than 40% in Kyoto, approximately 40% in Hyogo, slightly more than 40% in Nara, and slightly more than 20% in Wakayama. The use rate of beds for severe cases is slightly more than 30% in Nara.
In Fukuoka, the number of new cases of infection is approximately 249, with a ratio of this week to last week of less than 1 (0.77). They are mainly people in their 20s. The use rate of beds is slightly more than 30%. In Saga, Nagasaki, Kumamoto, Oita, Miyazaki, and Kagoshima, the number of new cases of infection is about 175, 106, 158, 125, 130, and 136, respectively, with a ratio to that for the previous week of less than 1 (0.67, 0.67, 0.63, 0.77, 0.88, and 0.91). The use rate of beds is slightly more than 20% in Saga, approximately 20% in Nagasaki, approximately 30% in Kumamoto, slightly more than 20% in Oita, slightly less than 20% in Miyazaki, and slightly less than 40% in Kagoshima.
The number of new cases of infection was approximately 291, with a ratio of this week to last week of 1.0. The newly infected individuals are mainly in their 20s or younger, and attention should be paid to an increasing trend among those in their 20s. The use rate of beds is slightly more than 20%.
Among 18 prefectures in which the application of priority areas has been lifted, besides the above-mentioned 15 prefectures, Aomori, Ishikawa, and Kagawa had a ratio of this week to last week lower than 1 at 0.96, 0.79, and 0.78, respectively, with the number of new cases being approximately 271, 184, and 232. The use rate of beds is slightly less than 30% in Aomori and Ishikawa, and slightly more than 30% in Kagawa.
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, aerosol inhalation, contact infection, etc.).
It has been suggested that infection with the Omicron variant may present 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. Limited data also indicate that the incidence of pneumonia in infection with the Omicron variant is higher than that in seasonal influenza. Further investigations, using various analyses are needed.
Viral shedding in individuals infected with the Omicron variant decreases over time. In patients with symptoms, it has been shown that the possibility of viral shedding is low 10 days after the date of onset. In patients with no symptoms, it has been shown that viral shedding does not occur 8 days after the date of diagnosis.
For infection with the Omicron variant, the preventive effect of a first vaccination against disease onset is 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 booster vaccination restores the infection-preventing effect, onset-preventing effect, and hospitalization-preventing effect against Omicron variant infection, as well as how these vaccine effects are attenuated after booster vaccination. Overseas, a fourth vaccination has been started in some countries. It is necessary to collect information on efficacy and safety, and to examine the need for a fourth vaccination in Japan, and the eligible persons, starting time, etc.
In some areas overseas, the number of cases of infection with the BA.2 lineage is increasing. In Japan, both the BA.1 lineage and the BA.1.1 lineage of the Omicron variant initially entered from overseas, after which the BA.1.1 lineage became the majority strain, and is still dominant. However, the BA.2 lineage has begun to be detected at quarantine stations and other domestic facilities, and replacement with the BA.2 lineage is progressing. Therefore, this may affect the pace of the increase (decrease) in the number of cases of infection. Analyses of the effective reproduction number, risk of domestic secondary infection, and other indices have shown that the infectivity of the BA.2 lineage is higher than that of the BA.1 lineage. The generation time in the BA.2 lineage was 15% shorter than that in the BA.1 lineage, indicating that the effective reproduction number was 26% higher. In comparing the severity of the BA.1 lineage and BA.2 lineage, some animal studies suggest that the BA.2 lineage may be more pathogenic, but it has also been reported that there is no difference in the actual risk of hospitalization or aggravation. In addition, a report from the UK indicates that there is no difference in the preventive effect of vaccination, between these two lineages. In the UK, a small number of cases of reinfection with the BA.2 lineage after infection with the BA.1 lineage have been reported, but the specific details of these cases are still unknown.
It is necessary to consider effective and appropriate surveillance, in order to properly grasp trends regarding occurrences. As a system of mutant strain monitoring, genomic surveillance should be continued in order to monitor the trend regarding replacement of the BA.1 lineage with the BA.2 lineage. For severe cases, clusters, or other applicable cases, confirmation via PCR testing for mutant strains and a whole-genome analysis is required.
Based on the infection status in each area, local governments must continue to work on securing the required number of beds and healthcare professionals, securing the functions of public health centers, which are indispensable for local communities, along with support for strengthening the healthcare center system, and establishing home-visit and online medical care systems for home care recipients. It is still necessary to secure a system for prompt administration of oral therapeutic drugs and neutralizing antibody drugs, for patients with a risk of developing severe disease, such as elderly patients and patients with underlying diseases. It is also necessary to establish a system that allows COVID-19 patients with an underlying disease to continue treatment for the underlying disease.
Implementation of efficient public health center operations are required, based on the administrative notice, such as prioritization of health observation and streamlining the handling of patient outbreak notifications.
In addition, in the identification and home quarantine on close contacts, it is necessary in principle to take appropriate measures against infections according to the local infection status, and taking into account the characteristics of Omicron variant (such as the short incubation period and interval of onset) and the status of the spread of infection, it is necessary to focus on the cases of infection at facilities such as medical institutions and elderly facilities where people at particularly high risk of severe disease are admitted. At the same time, it is important to establish an environment where people can take a break from work or school if they feel even a little unwell.
The rate of receiving a third vaccination has exceeded approximately 76% for the elderly aged 65 years and older, and roughly 35% overall. However, in order to minimize the number of severe and fatal cases, especially in the elderly, while at the same time ensuring that the other infection indices take a downward turn, it is necessary to proceed promptly with vaccinations for the elderly, and to provide booster vaccinations ahead of the original schedule for eligible persons under the age of 65, as much as possible.
It is important for local governments to promote the provision of information on vaccination. Along with vaccination of unvaccinated individuals, booster vaccination six months or more after the initial vaccination will restore vaccine effectiveness against the Omicron variant as well, and therefore booster vaccination must also be steadily implemented. Vaccinated individuals have also been reported to have a lower risk of corona sequelae.
In addition, vaccination of children aged 5 to 11 has begun. Although it is being carried out as a special temporary vaccination, it is necessary to proceed with vaccination taking into account that the obligation to make efforts does not apply to these children. In anticipation of preventing infections in children, it is also important for parents and the adults around them to be vaccinated.
Together with measures such as shortening the waiting period for immigrants from March, it is necessary to continue to verify the step-by-step review of border quarantine measures, while taking into account the status of mutant strains overseas and in Japan. In particular, attention should be paid to the recent epidemic status in the East Asian region. For individuals who are found to be positive by an entrance test, a whole-genome analysis should continue to be performed, to monitor the strains that are spreading overseas.
In situations and places where infection is widespread, it is necessary to strengthen and thoroughly implement infection control measures based on the characteristics of Omicron variant.
Figures (Number of new infections reported etc.) (PDF)
76th meeting of the COVID-19 advisory boardof Ministry of Health, Labour and Welfare (March 15, 2022). Material 1
Effective reproduction number: On a national basis, the most recent number is below 1 (0.97; as of February 27). The figure stands at 0.97 in the Tokyo metropolitan area and 0.94 in the Kansai area.
* The value for new cases of infection is the number of persons per 100,000 among the total number for the latest week, based on reporting dates.
The number of new cases of infection is approximately 214 (approximately 268 in Sapporo City), with a ratio to that for the previous week of less than 1 (0.90). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 30%.
In Aomori, the number of new cases of infection is approximately 279, with a ratio to that for the previous week of more than 1 (1.08). The infected individuals are mainly in their 30s or younger, among whom the number of those under the age of 10 is particularly high. The use rate of beds is slightly more than 40%.
In Gunma, the number of new cases of infection is approximately 215, with a ratio to that for the previous week of less than 1 (0.98). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 40%. In Tochigi, the number of new cases of infection is approximately 189, with a ratio to that for the previous week of less than 1 (0.91). In Ibaraki, the number of new cases of infection is approximately 350, with a ratio to that for the previous week of more than 1 (1.03). The use rate of beds is slightly more than 30% in Ibaraki, and slightly less than 30% in Tochigi.
In Tokyo, the number of new cases of infection is the highest in Japan (approximately 430); however, its ratio to that for the previous week is less than 1 (0.83). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 40%, while the use rate of beds for severe patients is slightly less than 40%. In Saitama, Chiba, and Kanagawa, the number of new cases of infection is approximately 357, 349, and 402, respectively, with a ratio to that for the previous week of less than 1 (0.87, 0.91, and 0.86, respectively). The use rate of beds is slightly more than 40% in Saitama, and slightly more than 50% in Chiba and Kanagawa. The use rate of beds for severe patients is approximately 20% in Saitama, slightly more than 10% in Chiba, and slightly less than 30% in Kanagawa.
In Ishikawa, the number of new cases of infection is approximately 231, with a ratio to that for the previous week of less than 1 (0.89). The infected individuals are mainly in their 20s or younger. The number of those under the age of 10 remains at a high level. The use rate of beds is slightly more than 20%.
In Aichi, the number of new cases of infection is approximately 299, with a ratio to that for the previous week of less than 1 (0.79). The infected individuals are mainly in their 20s or younger. The use rate of beds is slightly more than 50%, while the use rate of beds for severe patients is slightly less than 20%. In Gifu and Shizuoka, the number of new cases of infection is approximately 188 and 226, respectively, with a ratio to that for the previous week of less than 1 (0.93 and 0.94, respectively). The use rate of beds is slightly less than 40% in Gifu and approximately 30% in Shizuoka.
In Osaka, the number of new cases of infection is approximately 417, with a ratio to that for the previous week of less than 1 (0.78). The infected individuals are mainly in their 30s or younger. The use rate of beds is approximately 60%, while the use rate of beds for severe patients is approximately 50%. In Kyoto and Hyogo, the number of new cases of infection is approximately 298 and 343, respectively, with a ratio to that for the previous week of less than 1 (0.83 and 0.84, respectively). The use rate of beds is slightly more than 40% in Kyoto and approximately 50% in Hyogo. The use rate of beds for severe patients is slightly more than 20% in Kyoto.
In Kagawa, the number of new cases of infection increased to approximately 301, with a ratio to that for the previous week of 1.08. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 40%, while the use rate of beds for severe patients is slightly more than 20%.
In Kumamoto, the number of new cases of infection is approximately 262, with a ratio to that for the previous week of more than 1 (1.10). The infected individuals are mainly in their 20s or younger. The use rate of beds is slightly more than 30%.
The number of new cases of infection decreased to approximately 308, with a ratio to that for the previous week of 0.81. The newly infected individuals are mainly in their 20s or younger. The number of those in their teens increased. The use rate of beds is approximately 30%, while the use rate of beds for severe patients is slightly more than 20%.
In Yamagata, Fukushima, Niigata, Fukui, Yamanashi, Nagano, Hiroshima, Yamaguchi, Ehime, and Miyazaki, the number of new cases of infection is approximately 156, 158, 129, 359, 190, 125, 172, 156, 147, and 146, respectively. All of these prefectures show an increase, with a ratio to that for the previous week of more than 1. In Iwate, Miyagi, Akita, Toyama, Mie, Shiga, Nara, Wakayama, Tottori, Shimane, Okayama, Tokushima, Kochi, Fukuoka, Saga, Nagasaki, Oita, and Kagoshima, the number of new cases of infection is approximately 142, 185, 143, 256, 196, 356, 384, 146, 101, 103, 182, 187, 192, 331, 264, 165, 168, and 153, respectively. All of these prefectures have a ratio to that for the previous week of less than 1. The use rate of beds is slightly more than 30% in Iwate, Akita, Yamaguchi, and Miyazaki, slightly more than 20% in Miyagi, Niigata, Toyama, Nagano, Mie, Wakayama, and Tokushima, slightly less than 40% in Yamagata and Yamanashi, approximately 30% in Fukushima, Shimane, Okayama, Hiroshima, Ehime, Kochi, and Oita, slightly less than 30% in Fukui and Saga, approximately 60% in Shiga and Nara, slightly more than 40% in Fukuoka and Kagoshima, and approximately 20% in Nagasaki. The use rate of beds for severe patients is slightly less than 60% in Nara and approximately 20% in Ehime.
* The use rate of beds and the use rate of beds for severe patients are shown on the website of the Cabinet Secretariat.
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, aerosol inhalation, contact infection, etc.).
It has been suggested that infection with the Omicron variant may present 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. Limited data also indicate that the incidence of pneumonia in infection with the Omicron variant is higher than that in seasonal influenza. Further investigations, using various analyses are needed.
Viral shedding in individuals infected with the Omicron variant decreases over time. In patients with symptoms, it has been shown that the possibility of viral shedding is low 10 days after the date of onset. In patients with no symptoms, it has been shown that viral shedding does not occur 8 days after the date of diagnosis.
For infection with the Omicron variant, the preventive effect of a first vaccination against disease onset is 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 booster vaccination restores the infection-preventing effect, onset-preventing effect, and hospitalization-preventing effect against Omicron variant infection, as well as how these vaccine effects are attenuated after booster vaccination.
In some areas overseas, the number of cases of infection with the BA.2 lineage is increasing. In Japan, both the BA.1 lineage and the BA.1.1 lineage of the Omicron variant initially entered from overseas, after which the BA.1.1 lineage became the majority strain, and is still dominant. However, the BA.2 lineage has begun to be detected at quarantine stations and other domestic facilities, and replacement with the BA.2 lineage is progressing. This may affect the pace of the increase (decrease) in the number of cases of infection. Analyses of the effective reproduction number, risk of domestic secondary infection, and other indices have shown that the infectivity of the BA.2 lineage is higher than that of the BA.1 lineage. The generation time in the BA.2 lineage was 15% shorter than that in the BA.1 lineage, indicating that the effective reproduction number was 26% higher. In comparing the severity of the BA.1 lineage and BA.2 lineage, some animal studies suggest that the BA.2 lineage may be more pathogenic, but it has also been reported that there is no difference in the actual risk of hospitalization or aggravation. In addition, a report from the UK indicates that there is no difference in the preventive effect of vaccination, between these two lineages. In the UK, a small number of cases of reinfection with the BA.2 lineage after infection with the BA.1 lineage have been reported, but the specific details of these cases are still unknown.
occurrences. As a system of mutant strain monitoring, genomic surveillance should be continued in order to monitor the trend regarding replacement of the BA.1 lineage with the BA.2 lineage. For severe cases, clusters, or other applicable cases, confirmation via PCR testing for mutant strains and a whole-genome analysis is required.
Based on the infection status in each area, local governments must continue to work on securing the required number of beds and healthcare professionals, securing the functions of public health centers, which are indispensable for local communities, along with support for strengthening the healthcare center system, and establishing home-visit and online medical care systems for home care recipients. It is still necessary to secure a system for prompt administration of oral therapeutic drugs and neutralizing antibody drugs, for patients with a risk of developing severe disease, such as elderly patients and patients with underlying diseases.
In cases of difficult emergency transportation, both suspected non-COVID-19 cases and suspected COVID-19 cases remain at high levels. Attention should be given to the balance between medical care for COVID-19 and regular medical care, especially for emergency medical care. It is necessary to secure prompt access to consultations and condition monitoring for those at a higher risk of developing severe disease. It is also necessary to establish a system that allows COVID-19 patients with an underlying disease to continue treatment for the underlying disease.
Implementation of efficient public health center operations are required, based on the administrative notice, such as prioritization of health observation and streamlining the handling of patient outbreak notifications. In addition, the optimization of measures based on the characteristics of the epidemic strain needs to be examined. In particular, strategies for the identification of persons who have had close contact with infected individuals and their standby (targets, etc.) should be reviewed, as public health centers currently need more time to identify such persons, due to the high-level epidemic of infection with the Omicron variant. Regardless of survey results or the identification of persons who have had close contact with infected individuals, it is important to thoroughly implement infection prevention measures throughout society, and to establish an environment where people can take leaves from school or the workplace, in the case of poor health conditions.
The rate of receiving a third vaccination has exceeded approximately 70% for the elderly aged 65 years and older, and roughly 30% overall. However, in order to minimize the number of severe and fatal cases, especially in the elderly, while at the same time ensuring that the other infection indices take a downward turn, it is necessary to proceed promptly with vaccinations for the elderly, and to provide booster vaccinations ahead of the original schedule for eligible persons under the age of 65, as much as possible.
It is important for local governments to promote the provision of information on vaccination. Along with vaccination of unvaccinated individuals, booster vaccination six months or more after the initial vaccination will restore vaccine effectiveness against the Omicron variant as well, and therefore booster vaccination must also be steadily implemented. Vaccinated individuals have also been reported to have a lower risk of corona sequelae.
In addition, vaccination of children aged 5 to 11 has begun. Although it is being carried out as a special temporary vaccination, it is necessary to proceed with vaccination taking into account that the obligation to make efforts does not apply to these children. In anticipation of preventing infections in children, it is also important for parents and the adults around them to be vaccinated.
Together with measures such as shortening the waiting period for immigrants from March, it is necessary to continue to verify the step-by-step review of border quarantine measures, while taking into account the status of mutant strains overseas and in Japan. In particular, attention should be paid to the recent epidemic status in the East Asian region. For individuals who are found to be positive by an entrance test, a whole-genome analysis should continue to be performed, to monitor the strains that are spreading overseas.
In situations and places where infection is widespread, it is necessary to strengthen and thoroughly implement infection control measures based on the characteristics of Omicron variant.
Figures (Number of new infections reported etc.) (PDF)
75th meeting of the COVID-19 advisory boardof Ministry of Health, Labour and Welfare (March 9, 2022). Material 1
Effective reproduction number: On a national basis, the most recent number is below 1 (0.95 as of February 20), while the figure stands at 0.95 in the Tokyo metropolitan area and 0.93 in the Kansai area.
* The value for new cases of infection is the number of persons per 100,000 among the total number for the latest week, based on reporting dates.
The number of new cases of infection was approximately 234 (about 317 in Sapporo City), with a ratio of this week to last week of less than 1 (0.82). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 40%.
In Aomori, the number of new cases of infection increased to approximately 256, with a ratio of this week to last week of 1.09. They are mainly in their 30s or younger, with the number of those under 10 particularly increasing. The use rate of beds is slightly less than 50%.
In Gunma, the number of new cases of infection is approximately 217, with a ratio of this week to last week of less than 1 (0.96). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 50%, while the use rate of beds for severe cases is slightly more than 20%. In Tochigi, the number of new cases of infection was approximately 201, with a ratio of this week to last week of less than 1 (0.81). In Ibaraki, the ratio of this week to last week increased to 1.13, with approximately 340 new cases of infection. The use rate of beds is slightly less than 40% in Ibaraki and slightly more than 30% in Tochigi.
In Tokyo, the number of new cases of infection is approximately 497, with a ratio of this week to last week of less than 1 (0.88). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 50%, while the use rate of beds for severe patients is approximately 40%. In Saitama, Chiba, and Kanagawa, the number of new cases of infection was approximately 386, 376 and 452, respectively, with a ratio of this week to last week of less than 1 (0.90, 0.94 and 0.97). The use rate of beds is slightly more than 50% in Saitama, approximately 60% in Chiba and slightly more than 60% in Kanagawa. The use rate of beds for severe cases is slightly less than 20% in Saitama, slightly more than 10% in Chiba and slightly more than 30% in Kanagawa.
In Ishikawa, the number of new cases of infection is approximately 245, with a ratio of this week to last week of less than 1 (0.91). The infected individuals are mainly in their 30s or younger. In particular, it increased in teenagers, and the number of people under the age of 10 remained at a high level. The use rate of beds is slightly more than 30%.
In Aichi, the ratio of this week to last week was less than 1 (0.88), with the number of new cases of infection at approximately 373. The infected individuals are mainly in their 30s or younger. The use rate of beds is approximately 60%, while the use rate of beds for severe cases is slightly more than 20%. In Gifu and Shizuoka, the ratio of this week to last week was less than 1 (0.82 and 0.90, respectively), and number of new cases of infection was approximately 200 and 239. The use rate of beds is slightly more than 40% in Gifu and Shizuoka.
In Osaka, the number of new cases of infection was the highest in Japan (approximately 507), but with a ratio of this week to last week of less than 1 (0.79). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 70%, while the use rate of beds for severe cases is slightly more than 50%. In Kyoto and Hyogo, the number of new cases of infection was 353 and 399, respectively, with a ratio of this week to last week of less than 1 (0.83 and 0.90). The use rate of beds is slightly more than 60% in Kyoto and approximately 60% in Hyogo. The use rate of beds for severe cases is slightly more than 30% in Kyoto and slightly more than 20% in Hyogo.
In Kagawa, the number of new cases of infection was approximately 281, with a ratio of this week to last week of less than 1 (0.99). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 30%, while the use rate of beds for severe cases is approximately 20%.
In Kumamoto, the number of new cases of infection increased to approximately 252, with a ratio of this week to last week of 1.11. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 40%.
The number of new cases of infection has increased continuously to approximately 365, with a ratio of this week to last week of 1.13. The newly infected individuals are mainly in their 30s or younger, with the number of those in their 50s and younger increasing. The use rate of beds is slightly more than 40%, while the use rate of beds for severe cases is slightly more than 30%.
In Miyagi, Akita, Yamagata, Fukushima, Fukui, Shimane, Yamaguchi, Ehime, Kochi, and Saga, the number of new cases of infection is approximately 193, 152, 130, 134, 350, 105, 153, 144, 193, and 293, respectively. All of these prefectures show an increase, with a ratio of this week to last week of more than 1. In Miyazaki the ratio of this week to last week was 1.0, about 140. In Iwate, Niigata, Toyama, Yamanashi, Nagano, Mie, Shiga, Nara, Wakayama, Tottori, Okayama, Hiroshima, Tokushima, Fukuoka, Nagasaki, Oita, and Kagoshima, the number of new cases of infection is approximately 149, 109, 304, 182, 118, 213, 386, 462, 174, 122, 202, 160, 236, 356, 175, 194, and 172, respectively. All of these prefectures had a ratio of this week to last week of less than 1. The use rate of beds is approximately 40% in Iwate and Miyazaki, slightly more than 30% in Miyagi, Yamagata, Fukushima, Nagano, Mie, Wakayama, Shimane, Tokushima, Ehime, Saga, and Oita, slightly less than 40% in Akita, Hiroshima, and Kochi, slightly more than 20% in Niigata, Fukui, Tottori, and Nagasaki, slightly less than 30% in Toyama, slightly more than 40% in Yamanashi, Okayama, Yamaguchi, and Kagoshima, slightly more than 70% in Shiga, approximately 60% in Nara, and slightly more than 50% in Fukuoka. The use rate of beds for severe cases is about 20% in Miyagi, Tokushima, and Ehime, slightly less than 70% in Nara, and slightly less than 30% in Kochi.
* The bed use rate and bed use rate for severe cases are shown on the website of the Cabinet Secretariat.
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 occur through the same opportunities as before (spending time indoors with insufficient ventilation, eating and drinking, etc.), and infection is considered to occur via the same routes as before (droplets, aerosol inhalation, contact infection, etc.).
It has been suggested that infection with the Omicron variant may present a relatively lower risk of hospitalization and aggravation than does the Delta variant. However, the number of cases of hospitalization due to the Omicron variant infection has already increased. The case fatality rate of infection with the Omicron variant analyzed at this time is considered to be higher than that of seasonal influenza. Although the limited data suggest that the incidence of pneumonia is higher than that of seasonal influenza, it needs to be investigated by various analyses.
Viral shedding in individuals infected with the Omicron variant decreases over time, regardless of their vaccination status. It has been shown that viral shedding is less likely in symptomatic individuals after 10 days from the date of onset, and less likely in asymptomatic individuals after 8 days from the date of diagnosis.
For infection with the Omicron variant, the preventive effect of a first vaccination against disease onset is markedly reduced, but its preventive effect on hospitalization is maintained to a certain extent. It has also been reported from overseas that booster vaccination restores the infection-preventing effect, onset-preventing effect, and hospitalization-preventing effect against Omicron variant infection, and the attenuation of vaccine effect after booster vaccination. In Japan, there is a preliminary report of a case-control study on the efficacy of SARS-CoV-2 vaccines against the Omicron variant by two and three inoculations, and findings on the vaccine effectiveness against the Omicron variant have been increasing.
In some areas overseas, the number of cases of infection with the BA.2 lineage is increasing. In Japan, the Omicron variant initially had an influx of BA.1 and BA.1.1 from overseas, but after that, BA.1.1 became the majority and is still the mainstream, but the BA.2 lineage has also been detected in quarantine and in Japan, and it is estimated that the replacement with the BA.2 lineage will progress in the future. In this case, the rate of increase (decrease) of the number of cases of infection may be affected. Analyses of the effective reproduction number, risk of secondary infection, and other indices have shown that the infectivity of the BA.2 lineage is higher than that of the BA.1 lineage. The generation time in the BA.2 lineage was 15% shorter than that in the BA.1 lineage, indicating that the effective reproduction number was 26% higher. In comparing the severity of the BA.1 lineage and BA.2 lineage, some animal studies suggest that the BA.2 lineage may be more pathogenic, but it has also been reported that there is no difference in the actual risk of hospitalization or aggravation. A report from the UK also shows that there is no difference in the preventive effect of the vaccine. The risk of reinfection with the BA.2 lineage virus after infection with the BA.1 lineage virus is still unknown.
Effective and appropriate surveillance must be considered in order to understand the trends of occurrence. Regarding the monitoring system for mutant strains, it is necessary to continue monitoring trends by genome surveillance in regions where a strain has been replaced with the Omicron variant. For severe cases, clusters, or other applicable cases, confirmation by PCR test for mutant strains and whole-genome analysis is required.
Based on the infection status of the region and forecasts of the numbers of infected cases and severe cases, local governments must work flexibly to secure the required number of beds and healthcare professionals, secure the functions of public health centers, which are indispensable for local communities, along with support for strengthening the healthcare center system, and establish home-visit and online medical care systems for home care recipients. At that time, it is necessary to secure a system for prompt administration of oral therapeutic drugs and neutralizing antibody drugs, for patients at risk of developing severe disease, such as elderly patients and patients with underlying diseases.
Since patients with acute diseases other than COVID-19 who require emergency transportation often appear during this period, attention should be given to the balance between medical care for COVID-19 and regular medical care. If the infection spreads rapidly, it will be necessary to secure prompt access to consultation and condition monitoring for those at a higher risk of developing severe disease. In addition, a system must be established that allows COVID-19 patients with an underlying disease to continue treatment for the underlying disease.
Implementation of efficient public health center operations are required, based on the administrative notice, such as prioritization of health observation and streamlining the handling of patient outbreak notifications. In addition, the optimization of measures based on the characteristics of the epidemic strain needs to be examined. In particular, regarding the identification and waiting of close contacts, considering that the infection level is high and it takes time to identify close contacts at public health centers due to the epidemic of Omicron variant, it is necessary to consider strategies such as the target.
Regarding the rate of third vaccination, it exceeded about 60% for the elderly aged 65 and older, and about 25% overall. However, in order to minimize the number of severe and fatal cases, especially in the elderly, and at the same time to ensure that the current infection situation is on a downward trend, in addition to proceeding quickly with inoculation of the elderly, booster vaccination should be advanced to subjects under the age of 65 as much as possible.
It is important for local governments to promote the provision of information on vaccination. Along with vaccination of unvaccinated individuals, booster vaccination six months or more after the initial vaccination will restore vaccine effectiveness against the Omicron variant as well, and therefore booster vaccination must also be steadily implemented. Vaccinated individuals have also been reported to have a lower risk of corona sequelae.
In addition, vaccination of children aged 5 to 11 has begun. Although it is being carried out as a special temporary vaccination, it is necessary to proceed with vaccination taking into account that the obligation to make efforts does not apply to these children. In anticipation of preventing infections in children, it is also important for parents and adults around them to be vaccinated.
Together with implementing measures such as easing the waiting period for immigrants from March, it is necessary to continue to verify the step-by-step review of quarantine measures, taking into account the status of mutant strains such as the Omicron variant overseas and in Japan. For individuals found to be positive by an entrance test, a whole-genome analysis should continue to be performed, to monitor the strains that are spreading overseas.
In situations and places where infection is widespread, it is necessary to strengthen and thoroughly implement infection control measures based on the characteristics of Omicron variant.
Figures (Number of new infections reported etc.) (PDF)
74th meeting of the COVID-19 advisory boardof Ministry of Health, Labour and Welfare (March 2, 2022). Material 1
Effective reproduction number: On a national basis, the most recent number is below 1 (0.97 as of February 13), while the figure stands at 0.96 in the Tokyo metropolitan area and the Kansai area.
* The value for new cases of infection is the number of persons per 100,000 among the total number for the latest week, based on reporting dates.
The number of new cases of infection was approximately 286 (about 391 in Sapporo City), with a ratio of this week to last week of less than 1 (0.82). The infected individuals are mainly in their 30s or younger. The use rate of beds is approximately 40%.
In Aomori, the number of new cases of infection is approximately 234, with a ratio of this week to last week of less than 1 (0.94). They are mainly in their 30s or younger, with the number of those under 10 particularly increasing. The use rate of beds is approximately 50%. In Fukushima, the number of new cases of infection was approximately 113 with a ratio of this week to last week of less than 1 (0.92). The use rate of beds is slightly less than 50%.
In Gunma, the number of new cases of infection is approximately 227, with a ratio of this week to last week of less than 1 (0.88). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 50%, while the use rate of beds for severe cases is slightly more than 20%. In Ibaraki and Tochigi, the number of new cases of infection was approximately 301 and 248, respectively, with a ratio of this week to last week of less than 1 (0.93 and 0.88). The use rate of beds is slightly more than 40% in Ibaraki and slightly less than 40% in Tochigi. The use rate of beds for severe cases is approximately 20% in Ibaraki and Tochigi.
In Tokyo, the number of new cases of infection is approximately 564, with a ratio of this week to last week of less than 1 (0.81). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 50%, while the use rate of beds for severe cases is slightly more than 40%. In Saitama, Chiba, and Kanagawa, the number of new cases of infection was approximately 428, 399 and 467, respectively, with a ratio of this week to last week of less than 1 (0.84, 0.81 and 0.84). The use rate of beds is slightly more than 50% in Saitama, slightly more than 60% in Chiba and approximately 70% in Kanagawa. The use rate of beds for severe cases is approximately 20% in Saitama and Chiba and slightly less than 40% in Kanagawa.
In Ishikawa, the number of new cases of infection has increased continuously to approximately 268, with a ratio of this week to last week of 1.09. They are mainly in their 30s or younger, with the number of those under 10 particularly increasing. The use rate of beds is slightly more than 30%. In Niigata and Nagano, the number of new cases of infection was approximately 133 and 119, respectively, with a ratio of this week to last week of less than 1 (0.88 and 0.77). The use rate of beds is slightly more than 20% in Niigata and slightly more than 30% in Nagano.
In Aichi, the ratio of this week to last week was less than 1 (0.84), with the number of new cases of infection at approximately 424. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 60%, while the use rate of beds for severe cases is approximately 30%. In Gifu, Shizuoka and Mie, the ratio of this week to last week was less than 1 (0.79, 0.95, and 0.87, respectively), with the number of new cases of infection at approximately 243, 266 and 229. The use rate of beds is slightly more than 40% in Gifu, slightly less than 50% in Shizuoka, and slightly more than 40% in Mie.
In Osaka, the number of new cases of infection was the highest in Japan (approximately 638), but with a ratio of this week to last week of less than 1 (0.76). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 80%, while the use rate of beds for severe cases is slightly more than 50%. In Kyoto, Hyogo, and Wakayama, the number of new cases of infection was 426, 445, and 217, respectively, with a ratio of this week to last week of less than 1 (0.79, 0.79, and 0.78). The use rate of beds is slightly more than 70% in Kyoto, slightly less than 70% in Hyogo, and approximately 50% in Wakayama. The use rate of beds for severe cases is slightly more than 50% in Kyoto, and slightly more than 20% in Hyogo and Wakayama.
In Hiroshima, the number of new cases of infection is approximately 173, with a ratio of this week to last week of less than 1 (0.91). They are mainly in their 30s or younger, with the number of those under 10 remaining particularly high. The use rate of beds is slightly more than 40%. The use rate of beds for severe cases is slightly more than 20%. In Okayama, Kagawa, and Kochi, the number of new cases of infection has also decreased to approximately 217, 283, and 178, respectively, with a ratio of this week to last week of less than 1 (0.86, 0.94. and 0.89). The use rate of beds is slightly more than 40% in Okayama, slightly less than 40% in Kagawa, and approximately 40% in Kochi. The use rate of beds for severe cases is slightly less than 30% in Kochi.
In Fukuoka, the number of new cases of infection is approximately 406, with a ratio of this week to last week of less than 1 (0.85). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 60%. In Saga, Nagasaki, Kumamoto, Miyazaki, and Kagoshima, the number of new cases of infection is 289, 189, 227, 140, and 193, respectively, with a ratio of this week to last week of less than 1 (0.88, 0.98, 0.87, 0.97, and 0.93). The use rate of beds is approximately 30% in Saga, slightly less than 30% in Nagasaki, approximately 50% in Kumamoto, slightly more than 30% in Miyazaki, and approximately 40% in Kagoshima.
The number of new cases of infection increased to approximately 324, with a ratio of this week to last week of 1.12. The newly infected individuals are mainly in their 30s or younger, with the number of those in their teens and younger particularly increasing. The use rate of beds is approximately 50%, and the use rate of beds for severe cases is approximately 40%.
In Iwate, Akita, Toyama, Fukui, Tottori, Shimane, Tokushima, Ehime, and Oita, the number of new cases of infection is approximately 189, 150, 307, 284, 186, 92, 279, 125, and 199 , respectively. All of these prefectures show an increase, with a ratio of this week to last week of more than 1. In Miyagi, Yamagata, Yamanashi, Shiga, Nara, and Yamaguchi, the number of new cases of infection is 191, 122, 195, 451, 485, and 135, respectively, with a ratio of this week to last week of less than 1 (0.86, 0.91, 0.76, 0.95, 0.83, and 0.95). The use rate of beds is slightly less than 40% in Iwate and Akita, slightly more than 40% in Miyagi, slightly more than 30% in Toyama, Ehime and Oita, approximately 30% in Yamagata, slightly more than 20% in Fukui, Tottori and Shimane, slightly more than 50% in Yamanashi, slightly more than 70% in Shiga, slightly more than 60% in Nara, and approximately 40% in Yamaguchi and Tokushima. The use rate of beds for severe cases is approximately 70% in Nara.
* The bed use rate and bed use rate for severe cases are shown on the website of the Cabinet Secretariat.
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 occur through the same opportunities as before (spending time indoors with insufficient ventilation, eating and drinking, etc.), and infection is considered to occur via the same routes as before (droplets, aerosol inhalation, contact infection, etc.).
It has been suggested that infection with the Omicron variant may present a relatively lower risk of hospitalization and aggravation than does the Delta variant. However, the number of cases of hospitalization due to the Omicron variant infection has already increased. The case fatality rate of infection with the Omicron variant analyzed at this time is considered to be higher than that of seasonal influenza. Although the limited data suggest that the incidence of pneumonia is higher than that of seasonal influenza, it needs to be investigated by various analyses.
Viral shedding in individuals infected with the Omicron variant decreases over time, regardless of their vaccination status. It has been shown that viral shedding is less likely in symptomatic individuals after 10 days from the date of onset, and less likely in asymptomatic individuals after 8 days from the date of diagnosis.
For infection with the Omicron variant, the preventive effect of a first vaccination against disease onset is markedly reduced, but its preventive effect on hospitalization is maintained to a certain extent. It has also been reported from overseas that booster vaccination restores the infection-preventing effect, onset-preventing effect, and hospitalization-preventing effect against Omicron variant infection, and the attenuation of vaccine effect after booster vaccination. In Japan, there is a preliminary report of a case-control study on the efficacy of SARS-CoV-2 vaccines against the Omicron variant by two and three inoculations, and findings on the vaccine effectiveness against the Omicron variant have been increasing.
In some areas overseas, the number of cases of infection with the BA.2 lineage is increasing. Currently, the mainstream of the Omicron variant in Japan is the BA.1 lineage, but the BA.2 lineage has also been detected in quarantine and in Japan, and its proportion may increase. In this case, the rate of increase (decrease) of the number of cases of infection may be affected. Analyses of the effective reproduction number, risk of secondary infection, and other indices have shown that the infectivity of the BA.2 lineage is higher than that of the BA.1 lineage. The generation time in the BA.2 lineage was 15% shorter than that in the BA.1 lineage, indicating that the effective reproduction number was 26% higher. In comparing the severity of the BA.1 lineage and BA.2 lineage, some animal studies suggest that the BA.2 lineage may be more pathogenic, but it has also been reported that there is no difference in the actual risk of hospitalization or aggravation. A report from the UK also shows that there is no difference in the preventive effect of the vaccine. The risk of reinfection with the BA.2 lineage virus after infection with the BA.1 lineage virus is still unknown.
Effective and appropriate surveillance must be considered in order to understand the trends of occurrence. Regarding the monitoring system for mutant strains, it is necessary to continue monitoring trends by genome surveillance in regions where a strain has been replaced with the Omicron variant. For severe cases, clusters, or other applicable cases, confirmation by PCR test for mutant strains and whole-genome analysis is required.
Based on the infection status of the region and forecasts of the numbers of infected cases and severe cases, local governments must work flexibly to secure the required number of beds and healthcare professionals, secure the functions of public health centers, which are indispensable for local communities, along with support for strengthening the healthcare center system, and establish home-visit and online medical care systems for home care recipients. At that time, it is necessary to secure a system for prompt administration of oral therapeutic drugs and neutralizing antibody drugs, for patients at risk of developing severe disease, such as elderly patients and patients with underlying diseases.Since patients with acute diseases other than COVID-19 who require emergency transportation often appear during this period, attention should be given to the balance between medical care for COVID-19 and regular medical care. If the infection spreads rapidly, it will be necessary to secure prompt access to consultation and condition monitoring for those at a higher risk of developing severe disease. In addition, a system must be established that allows COVID-19 patients with an underlying disease to continue treatment for the underlying disease.
Implementation of efficient public health center operations are required, based on the recently issued administrative notice, such as prioritization of health observation and streamlining the handling of patient outbreak notifications. In addition, the optimization of measures based on the characteristics of the epidemic strain needs to be examined. In particular, regarding the identification and waiting of close contacts, considering that infection with the Omicron variant has a short generation time and incubation period, the effect of preventing the spread of infection is limited in situations where the infection level is high and it takes time to identify close contacts at the public health center, so it is necessary to consider strategies such as target people.
The rate of a third vaccination in the elderly aged 65 years and older has reached about 50%. However, in order to minimize the number of severe and fatal cases, especially in the elderly, and at the same time to ensure that the current infection situation is on a downward trend, in addition to further accelerating inoculation of the elderly, booster vaccination should be advanced to subjects under the age of 65 as much as possible.
It is important for local governments to promote the provision of information on vaccination. Along with vaccination of unvaccinated individuals, booster vaccination six months or more after the initial vaccination will restore vaccine effectiveness against the Omicron variant as well, and therefore booster vaccination must also be steadily implemented. Vaccination has also been reported to be effective against corona sequelae.
Vaccination of children from 5 to 11 years old is also necessary as a special temporary vaccination, and it is necessary to proceed with vaccination in the future taking into account that the obligation to make efforts does not apply to these children. In anticipation of preventing infections in children, it is also important for parents and adults around them to be vaccinated.
Together with implementing measures such as easing the waiting period for immigrants from March, it is necessary to continue to verify the step-by-step review of quarantine measures, taking into account the status of mutant strains such as the Omicron variant overseas and in Japan. For individuals found to be positive by an entrance test, a whole-genome analysis should continue to be performed, to monitor the strains that are spreading overseas.
In situations and places where infection is widespread, it is necessary to strengthen and thoroughly implement infection control measures based on the characteristics of Omicron variant.
Figures (Number of new infections reported etc.) (PDF)
73th meeting of the COVID-19 advisory boardof Ministry of Health, Labour and Welfare (February 24, 2022). Material 1
Effective reproduction number: On a national basis, the most recent number is below 1 (0.96 as of February 6), while the figure stands at 0.96 in the Tokyo metropolitan area and 0.95 in the Kansai area.
* The value for new cases of infection is the number of persons per 100,000 among the total number for the latest week, based on reporting dates.
The number of new cases of infection was approximately 340 (about 483 in Sapporo City), with a ratio of this week to last week of less than 1 (0.84). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 40%.
In Aomori, the number of new cases of infection increased to approximately 248, with a ratio of this week to last week of 1.14. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 50%. In Fukushima, the number of new cases of infection was approximately 118, with a ratio of this week to last week of less than 1 (0.81). The use rate of beds is approximately 50%.
In Gunma, the number of new cases of infection is approximately 253, with a ratio of this week to last week of less than 1 (0.94). The infected individuals are mainly in their 30s or younger. The use rate of beds is approximately 60%, while the use rate of beds for severe cases is slightly more than 30%. In Tochigi, the number of new cases of infection was approximately 270, with a ratio of this week to last week of less than 1 (0.95). In Ibaraki, the ratio of this week to last week increased to 1.02, with approximately 326 new cases of infection. The use rate of beds is slightly more than 40% in Ibaraki and approximately 40% in Tochigi. The use rate of beds for severe cases is approximately 20% in Ibaraki and Tochigi.
In Tokyo, the number of new cases of infection is approximately 678, with a ratio of this week to last week of less than 1 (0.90). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 60%, while the use rate of beds for severe cases is slightly less than 50%. In Saitama, Chiba, and Kanagawa, the number of new cases of infection was approximately 491, 476 and 542, respectively, with a ratio of this week to last week of less than 1 (0.99, 0.91 and 0.95). The use rate of beds is slightly more than 60% in Saitama, slightly less than 70% in Chiba and approximately 70% in Kanagawa. The use rate of beds for severe cases is slightly more than 20% in Saitama and Chiba and slightly more than 30% in Kanagawa.
In Ishikawa, the number of new cases of infection increased to approximately 250, with a ratio of this week to last week of 1.06. The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 40%. In Niigata and Nagano, the number of new cases of infection was approximately 149 and 147, respectively, with a ratio of this week t last week of less than 1 (0.97 and 0.85). The use rate of beds is slightly more than 20% in Niigata and approximately 40% in Nagano.
In Aichi, the ratio of this week to last week was less than 1 (0.92), with the number of new cases of infection at approximately 500. The infected individuals are mainly in their 30s or younger. The use rate of beds is about 70%, and the use rate of beds for severe cases is about 30%. In Gifu, Shizuoka and Mie, the ratio of this week to last week was less than 1 (0.91, 0.99 and 0.96, respectively), with the number of new cases of infection at approximately 293, 281 and 256. The use rate of beds is slightly less than 60% in Gifu and Shizuoka, and slightly more than 50% in Mie.
In Osaka, the number of new cases of infection was the highest in Japan (approximately 830), but with a ratio of this week to last week of less than 1 (0.91). The infected individuals are mainly in their 30s or younger. The use rate of beds is approximately 80%, while the use rate of beds for severe cases is slightly more than 50%. In Kyoto, Hyogo, and Wakayama, the number of new cases of infection was 530, 554, and 277, respectively, with a ratio of this week to last week of less than 1 (0.92, 0.91, and 0.83). The use rate of beds is slightly more than 70% in Kyoto and Hyogo, and slightly more than 50% in Wakayama. The use rate of beds for severe cases is slightly less than 50% in Kyoto, approximately 30% in Hyogo, and slightly more than 40% in Wakayama.
In Hiroshima, the number of new cases of infection is approximately 185, with a ratio of this week to last week of less than 1 (0.84). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 50%, while the use rate of beds for severe cases is slightly more than 20%. In Okayama and Kochi, the number of new cases of infection has also decreased to approximately 240 and 197, respectively, with a ratio of this week to last week of less than 1 (0.81 and 0.78). In Kagawa, the ratio of this week to last week increased to 1.25, with approximately 305 new cases of infection. The use rate of beds is slightly more than 50% in Okayama, slightly less than 50% in Kagawa, and slightly more than 40% in Kochi. The use rate of beds for severe cases is slightly more than 40% in Kochi.
In Fukuoka, the number of new cases of infection is approximately461, with a ratio of this week to last week of less than 1 (0.84). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 80%. In Saga, Nagasaki, Kumamoto, Miyazaki, and Kagoshima, the number of new cases of infection is 316, 185, 255, 145, and 205, respectively, with a ratio of this week to last week of less than 1 (0.86, 0.81, 0.83, 0.95, and 0.89). The use rate of beds is slightly more than 40% in Saga, approximately 30% in Nagasaki, slightly more than 50% in Kumamoto, slightly more than 30% in Miyazaki, and slightly less than 60% in Kagoshima. The use rate of beds for severe cases is slightly more than 20% in Kumamoto.
The number of new cases of infection increased to approximately 293, with a ratio of this week to last week of 1.11. The newly infected individuals are mainly in their 30s or younger, with the number of those in their teens particularly increasing. The use rate of beds and the use rate of beds for severe cases are both slightly more than 40%.
In Iwate, Miyagi, Akita, Yamagata, Toyama, Fukui, Yamanashi, Shiga, Nara, Tottori, Tokushima, and Ehime, the number of new cases of infection is approximately 147, 224, 148, 135, 296, 262, 246, 485, 576, 179, 253, and 117, respectively. All of these prefectures show an increase, with a ratio of this week to last week of more than 1. In Shimane, Yamaguchi, and Oita, the number of new cases of infection is 78, 142, and 188, respectively, with a ratio of this week to last week of less than 1 (0.96, 0.98, and 0.81, respectively). The use rate of beds is slightly more than 40% in Iwate, Yamagata, and Yamaguchi, slightly less than 50% in Miyagi, slightly more than 30% in Akita, Toyama, Tokushima, and Ehime, slightly more than 20% in Fukui, Tottori, and Shimane, slightly more than 50% in Yamanashi, approximately 70% in Shiga and Nara, and slightly less than 40% in Oita. The use rate of beds for severe cases is slightly more than 70% in Nara.
* The bed use rate and bed use rate for severe cases are shown on the website of the Cabinet Secretariat.
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 occur through the same opportunities as before (spending time indoors with insufficient ventilation, eating and drinking, etc.), and infection is considered to occur via the same routes as before (droplets, aerosol inhalation, contact infection, etc.).
It has been suggested that infection with the Omicron variant may present a relatively lower risk of hospitalization and aggravation than does the Delta variant. However, the number of cases of hospitalization due to the Omicron variant infection has already increased.
Viral shedding in individuals infected with the Omicron variant decreases over time, regardless of their vaccination status. It has been shown that viral shedding is less likely in symptomatic individuals after 10 days from the date of onset, and less likely in asymptomatic individuals after 8 days from the date of diagnosis.
For infection with the Omicron variant, the preventive effect of a first vaccination against disease onset is markedly reduced, but its preventive effect on hospitalization is maintained to a certain extent. It has also been reported from overseas that in addition to improving the preventive effects against disease onset and hospitalization for infection with the Omicron variant, a booster shot also improves recovery of the protective effect against infection. In Japan, there is a preliminary report of a case-control study on the efficacy of SARS-CoV-2 vaccines against the Omicron variant by two and three inoculations, and findings on the vaccine effectiveness against the Omicron variant have been increasing.
In some areas overseas, the number of cases of infection with the BA.2 lineage is increasing. Currently, the mainstream of the Omicron variant in Japan is the BA.1 lineage, but the BA.2 lineage has also been detected in quarantine and in Japan, and its proportion may increase. In this case, the rate of increase (decrease) of the number of cases of infection may be affected. Analyses of the effective reproduction number, risk of domestic secondary infection, and other indices have shown that the infectivity of the BA.2 lineage is higher than that of the BA.1 lineage. In comparing the severity of the BA.1 lineage and BA.2 lineage, some animal studies suggest that the BA.2 lineage may be more pathogenic, but it has also been reported that there is no difference in the actual risk of hospitalization or aggravation. A report from the UK also shows that there is no difference in the preventive effect of the vaccine.
Effective and appropriate surveillance must be considered in order to understand the trends of occurrence. Regarding the monitoring system for mutant strains, it is necessary to continue monitoring trends by genome surveillance in regions where a strain has been replaced with the Omicron variant. For severe cases, clusters, or other applicable cases, confirmation by PCR test for mutant strains and whole-genome analysis is required.
Based on the infection status of the region and forecasts of the numbers of infected cases and severe cases, local governments must work flexibly to secure the required number of beds and healthcare professionals, secure the functions of public health centers, which are indispensable for local communities, along with support for strengthening the healthcare center system, and establish home-visit and online medical care systems for home care recipients. At that time, it is necessary to secure a system for prompt administration of oral therapeutic drugs and neutralizing antibody drugs, for patients at risk of developing severe disease, such as elderly patients and patients with underlying diseases.
Since patients with acute diseases other than COVID-19 who require emergency transportation often appear during the winter, attention should be given to the balance between medical care for COVID-19 and regular medical care. If the infection spreads rapidly, it will be necessary to secure prompt access to consultation and condition monitoring for those at a higher risk of developing severe disease. In addition, a system must be established that allows COVID-19 patients with an underlying disease to continue treatment for the underlying disease.
Implementation of efficient public health center operations are required, based on the recently issued administrative notice, such as prioritization of health observation and streamlining the handling of patient outbreak notifications. In addition, the optimization of measures based on the characteristics of the epidemic strain needs to be examined.
Booster vaccinations must be further accelerated in order to ensure that the current infection situation is on a downward trend, and to minimize severe cases and deaths, especially in the elderly. The efficacy of vaccination against infection by the Omicron variant has also been confirmed. Vaccination has also been reported to be effective against corona sequelae. It is important for local governments to promote the provision of information on vaccination. Along with vaccination of unvaccinated individuals, booster vaccination six months or more after the initial vaccination will restore vaccine effectiveness, and therefore booster vaccination must also be steadily implemented. The number of infected individuals among the elderly may continue to increase in the future. Therefore, it is necessary to further accelerate vaccinations for the elderly and other eligible persons, and also to successively provide vaccination services ahead of the original schedule for the general public as well, as much as possible. Vaccination of children from 5 to 11 years old is necessary as a special temporary vaccination, and it is necessary to proceed with vaccination in the future taking into account that the obligation to make efforts does not apply to these children. In anticipation of preventing infections in children, it is also important for parents and adults around them to be vaccinated.
It is necessary to verify the epidemic situation of mutant strains such as the Omicron variant in Japan and overseas. For individuals found to be positive by an entrance test, a whole-genome analysis should continue to be performed, to monitor the strains that are spreading overseas.
In situations and places where infection is widespread, it is necessary to strengthen and thoroughly implement infection control measures based on the characteristics of Omicron variant.
Figures (Number of new infections reported etc.) (PDF)
72th meeting of the COVID-19 advisory boardof Ministry of Health, Labour and Welfare (February 16, 2022). Material 1
Effective reproduction number: On a national basis, the most recent number is below 1 (0.98; as of January 31), while the figure stands at 0.99 in the Tokyo metropolitan area and 0.97 in the Kansai area.
* The value for new cases of infection is the number of persons per 100,000 among the total number for the latest week, based on reporting dates.
The number of new cases of infection was approximately 419 (about 559 in Sapporo City), with a ratio that for to the previous week of less than 1 (0.91). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 30%.
In Aomori, the number of new cases of infection is approximately 213, with a ratio to that for the previous week of less than 1 (0.97). The infected individuals are mainly in their 20s or younger. The use rate of beds is approximately 50%. In Yamagata and Fukushima, the number of new cases of infection has also decreased to approximately 123 and 152, respectively, with a ratio to that for the previous week of less than 1 (0.72 and 0.78). The use rate of beds is slightly more than 40% in Yamagata and about 50% in Fukushima.
In Gunma, the number of new cases of infection is approximately 272, with a ratio to that for the previous week of less than 1 (0.78). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 60%, while the use rate of beds for severe cases is slightly more than 20%. In Ibaraki and Tochigi, the number of new cases of infection was approximately 332 and 273, respectively, with a ratio to that for the previous week of less than 1 (0.96 and 0.91). The use rate of beds is slightly less than 40% in Ibaraki and slightly more than 40% in Tochigi.
In Tokyo, the number of new cases of infection is approximately 758, with a ratio to that for the previous week of less than 1 (0.82). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly less than 60%, while the use rate of beds for severe cases is slightly more than 40%. In Saitama, Chiba, and Kanagawa, the number of new cases of infection was approximately 481, 526 and 574, respectively, with a ratio to that for the previous week of less than 1 (0.87, 0.98 and 0.94). The use rate of beds is slightly less than 60% in Saitama, slightly less than 70% in Chiba, and slightly more than 70% in Kanagawa. The use rate of beds for severe cases is slightly more than 20% in Saitama, approximately 20% in Chiba and slightly more than 40% in Kanagawa.
In Ishikawa, the number of new cases of infection is approximately 246, with a ratio to that for the previous week of less than 1 (0.83). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 60%, while the use rate of beds for severe cases is slightly more than 20%. In Niigata and Nagano, the number of new cases of infection was approximately 153 and 176, respectively, with a ratio to that for the previous week of less than 1 (0.98 and 0.91). The use rate of beds is slightly more than 20% in Niigata and slightly more than 40% in Nagano.
In Aichi, the number of new cases of infection has increased continuously to approximately 540, with a ratio to that for the previous week of 1.03. The infected individuals are mainly in their 30s or younger. The use rate of beds is approximately 70%, while the use rate of beds for severe cases is slightly more than 20%. In Gifu, the number of new cases of infection has increased continuously to approximately 318, with a ratio to that for the previous week of 1.05. In Shizuoka and Mie, the number of new cases of infection was approximately 290 and 266, respectively, with a ratio to that for the previous week of less than 1 (0.90 and 0.91). The use rate of beds is slightly less than 60% in Gifu, slightly more than 50% in Mie, and slightly more than 40% in Shizuoka.
In Osaka the number of new cases of infection was the highest in Japan (approximately 943), but with a ratio to that for the previous week of less than 1 (0.94). The infected individuals are mainly in their 30s or younger. The use rate of beds exceeded 100%, while the use rate of beds for severe cases is slightly more than 50%. In Kyoto, Hyogo, and Wakayama,, the number of new cases of infection is 592, 628, and 343, respectively, with a ratio to that for the previous week of less than 1 (0.86, 0.88, and 0.89). The use rate of beds is approximately 70% in Kyoto, slightly more than 70% in Hyogo, and slightly less than 70% in Wakayama. The use rate of beds for severe cases is slightly more than 60% in Kyoto, slightly more than 30% in Hyogo, and slightly less than 20% in Wakayama.
In Hiroshima, the number of new cases of infection is approximately 222, with a ratio to that for the previous week of less than 1 (0.83). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 50%, while the use rate of beds for severe patients is approximately 30%. In Okayama, Yamaguchi, and Kagawa, the number of new cases of infection has also decreased to approximately 306, 143, and 242, respectively, with a ratio to that for the previous week of less than 1 (0.78, 0.89, and 0.98). In Shimane and Kochi, the number of new cases of infection was approximately 86 and 256, respectively, with a ratio to that for the previous week increasing to 1.12 and 1.14. The use rate of beds is slightly less than 30% in Shimane, slightly more than 50% in Okayama, slightly less than 40% in Yamaguchi, and slightly less than 50% in Kagawa and Kochi. The use rate of beds for severe cases is slightly more than 20% in Okayama and slightly more than 40% in Kochi.
In Fukuoka, the number of new cases of infection is approximately563, with a ratio to that for the previous week of less than 1 (0.88). The infected individuals are mainly in their 30s or younger. The use rate of beds is slightly more than 80%. In Saga, Nagasaki, Kumamoto, Oita, Miyazaki, and Kagoshima, the number of new cases of infection is 374, 223, 310, 234, 163, and 241, respectively, with a ratio to that for the previous week of less than 1 (0.86, 0.81, 0.90, 0.87, 0.77, and 0.92). The use rate of beds is slightly more than 40% in Saga, Nagasaki and Oita, slightly more than 60% in Kumamoto, approximately 40% in Miyazaki, and slightly more than 50% in Kagoshima. The use rate of beds for severe cases is approximately 20% in Kumamoto.
The number of new cases of infection is approximately 268, and the ratio to that for the previous week remains less than 1 (0.91). In the Yaeyama and Miyako districts, the increase is continuing. The newly infected individuals are mainly in their 30s or younger. The use rate of beds is about 50%, and the use rate of beds for severe cases is about 50%.
In Iwate, Miyagi, Toyama, Fukui, Nara, and Tokushima, the number of new cases of infection is approximately 95, 211, 247, 207, 577, and 178, respectively. All of these prefectures show an increase, with a ratio to that for the previous week of more than 1. In Akita, Yamanashi, Shiga, Tottori, and Ehime, the number of new cases of infection is 131, 231, 426, 93, and 112, respectively, with a ratio to that for the previous week of less than 1 (0.99, 0.98, 0.86, 0.76, and 0.84). The use rate of beds is slightly more than 40% in Iwate and Miyagi, slightly more than 30% in Akita and Tokushima, slightly less than 70% in Yamanashi, approximately 30% in Toyama, slightly more than 20% in Fukui and Tottori, slightly more than 70% in Shiga and Nara, and slightly less than 40% in Ehime. The use rate of beds for severe cases is slightly more than 60% in Nara, and approximately 20% in Ehime.
* The bed use rate and bed use rate for severe cases are shown on the website of the Cabinet Secretariat.
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 occur through the same opportunities as before (spending time indoors with insufficient ventilation, eating and drinking, etc.), and infection is considered to occur via the same routes as before (droplets, aerosol inhalation, contact infection, etc.).
It has been suggested that infection with the Omicron variant may present a relatively lower risk of hospitalization and aggravation than does the Delta variant. However, the number of cases of hospitalization due to the Omicron variant infection has already increased.
Viral shedding in individuals infected with the Omicron variant decreases over time, regardless of vaccination status. In patients with symptoms, it has been shown that the possibility of viral shedding after Day 10 (when the date of onset is regarded as Day 0) is as low as in the case of infection with the conventional strain. In patients with no symptoms, it has been shown that the possibility of viral shedding is low 8 days after the date of diagnosis.
For infection with the Omicron variant, the preventive effect of a first vaccination against disease onset is markedly reduced, but its preventive effect on hospitalization is maintained at a certain level. It has also been reported from overseas that a booster shot improves the preventive effects against disease onset and hospitalization for infection with the Omicron variant. There was also a preliminary report of a case-control study on the efficacy of COVID-19 vaccines against the Omicron variant in Japan.
In some areas overseas, the number of cases of infection with the BA.2 lineage is increasing. Currently, the mainstream of the Omicron variant in Japan is the BA.1 lineage, but the BA.2 lineage has also been detected in quarantine and in Japan. Monitoring must be continued through a certain number of genome analyses. Analyses of the effective reproduction number, risk of domestic secondary infection, and other indices have shown that the infectivity of the BA.2 lineage is higher than that of the BA.1 lineage. According to a report from Denmark, there is no difference in the risk of hospitalization between the BA.1 lineage and the BA.2 lineage, in terms of severity. In addition, a report from the UK says that there is no difference in the preventive effect of vaccination between these lineages.
Effective and appropriate surveillance must be considered in order to understand the trends of occurrence. Regarding the monitoring system for mutant strains, it is necessary to continue monitoring trends by genome surveillance in regions where a strain has been replaced with the Omicron variant. For severe cases, clusters, or other applicable cases, confirmation by PCR test for mutant strains and whole-genome analysis is required.
While the infection is spreading nationwide, it is necessary to maintain a surveillance system according to the local infection status, including the situation regarding replacement with the Omicron variant. For severe patients, clusters, or other applicable cases, a genome analysis should also be performed to identify variants such as the Delta variant.
Based on the infection status of the region and forecasts of the numbers of infected cases and severe cases, local governments must work flexibly to secure the required number of beds and healthcare professionals, secure the functions of public health centers, which are indispensable for local communities, along with support for strengthening the healthcare center system, and establish home-visit and online medical care systems for home care recipients. At that time, it is necessary to secure a system for prompt administration of oral therapeutic drugs and neutralizing antibody drugs, for patients at risk of developing severe disease, such as elderly patients and patients with underlying diseases.
Since patients with acute diseases other than COVID-19 who require emergency transportation often appear during the winter, attention should be given to the balance between medical care for COVID-19 and regular medical care. If the infection spreads rapidly, it will be necessary to secure prompt access to consultation and condition monitoring for those at a higher risk of developing severe disease. In addition, a system must be established that allows COVID-19 patients with an underlying disease to continue treatment for the underlying disease.
Implementation of efficient public health center operations are required, based on the recently issued administrative notice, such as prioritization of health observation and streamlining the handling of patient outbreak notifications. In addition, the optimization of measures based on the characteristics of the epidemic strain needs to be examined.
Local governments are required to promote the provision of information on vaccination. Booster vaccinations, which have already been started, must also be implemented steadily, along with vaccinations for unvaccinated persons. The number of infected individuals among the elderly may continue to increase in the future. Therefore, it is necessary to further accelerate vaccinations for the elderly and other eligible persons, and also to successively provide vaccination services ahead of the original schedule for the general public as well, as much as possible. Vaccination of children from 5 to 11 years old is necessary as a special temporary vaccination, and it is necessary to proceed with vaccination in the future taking into account that the obligation to make efforts does not apply to these children.
It is necessary to verify the epidemic situation of mutant strains such as Omicron variant in Japan and overseas. For individuals found to be positive by an entrance test, a whole-genome analysis should continue to be performed, to monitor the strains that are spreading overseas.
In situations and places where infection is widespread, it is necessary to strengthen and thoroughly implement infection control measures based on the characteristics of Omicron variant.
Figures (Number of new infections reported etc.) (PDF)