76th meeting of the COVID-19 advisory boardof Ministry of Health, Labour and Welfare (March 15, 2022). Material 1

Evaluation of the latest infection status, etc.

Infection status

• The number of new cases of infection nationwide (by date of report) continued to decrease, to approximately 296 per 100,000 in the last week, with a ratio to that for the previous week of 0.87. The number of new cases of infection by age group continued to decrease in all age groups.
• Among the 18 prefectures under priority preventative measures, 14 of them continued to show a decrease in the number of new cases of infection, with a ratio to that for the previous week of less than 1. On the other hand, among the 13 prefectures where application of priority measures was lifted by the deadline of the 6th of this month, Fukushima, Niigata, Nagano, Hiroshima, and Miyazaki have a ratio to that for the previous week of more than 1.
• Along with the decrease in the number of new cases of infection nationwide, the numbers of patients receiving treatment, severe patients, and deaths continued to decrease.

  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.

Local trends

* 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.

< Areas under priority measures >

1. Hokkaido

   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%.

2. Tohoku

   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%.

3. North Kanto

   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.

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

   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.

5. Hokuriku

   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%.

6. Chukyo/Tokai

   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.

7. Kansai area

   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.

8. Shikoku

   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%.

9. Kyushu

   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%.

< Excepting Areas under prioirty measures >

1. Okinawa

   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%.

2. Areas other than the above

   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.

Future outlook and measures to be taken

• On a national basis, the number of new cases of infection has been gradually decreasing, with both a ratio to that for the previous week and an effective reproduction number of less than 1. Among newly infected individuals, the proportion of those in their teens or younger continues to increase, and remains at a high level. In the elderly, infections at nursing care facilities and medical facilities are continuing to occur.
• A continuous decrease in the number of cases of infection is being seen in many areas that were previously at a high infection level. However, in areas that were previously at a relatively low infection level, the number has stopped decreasing or even begun to increase, showing a weak tendency toward a decrease. The change in infection status differs between areas. Among infected individuals, the proportion of the elderly has increased in only a few areas, while that of those under the age of 10 has increased in areas where the number has stopped decreasing or increased. In some areas, an increasing tendency is being observed in various age groups.
• The nighttime population has increased in many areas where the application of priority measures was lifted, as well as areas that are currently under priority measures. Attention should be paid to the future trend in the number of cases of infection.
• The current status is different from the last summer’s status, where a constant decrease was seen after the infection spread. As the number of new cases of infection is now decreasing at a slow pace, it is expected that the number will continue to remain at a high level, for at least a while. Attention should be paid to the possibility that the number will increase again due to the emergence of the BA.2 lineage, as well as the impact on infection status due to spring breaks or the start of the new school/business year, when opportunities to meet people who rarely see each other will increase.
• Regarding the number of test-positive persons, it has been pointed out that delayed reporting may cause discrepancies between the published data and the actual status. It is therefore important to continuously monitor other indices when assessing the status of the epidemic.
• The pace of the decrease in the number of inpatients is slow, even in areas that are showing a continuous decrease in the number of new cases of infection. In many areas where the number of new cases of infection has stopped decreasing or increased, the number of inpatients has remained at the same level, or been decreasing slowly. The strain on systems for services such as medical care for patients with mild/moderate symptoms, and in some areas, the high use rate of beds due to elderly patients with severe symptoms may continue for some time.
• People aged 80 years and older account for a large proportion of deaths in this wave of the spread of the infection. Many of these persons had resided at medical or elderly facilities before they were found to be infected. It has been reported that not a few of these elderly people have died from causes other than COVID-19 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.

Findings on the characteristics of the Omicron variant

1. [Infectivity/transmissibility]

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

2. [Place/route of infection]

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

3. [Severity]

   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.

4. [Duration of viral shedding]

   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.

5. [Vaccine effect]

   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.

6. [BA.2 lineage]

   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.

Efforts based on the spread of infection with the Omicron variant

1. [Surveillance, etc.]

   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.

2. [Measures taken by local governments]

   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.

3. [Reinforcement of information provision to unvaccinated individuals and those receiving booster vaccinations]

   • 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.

4. [Quarantine measures]

   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.

Strengthening and thorough implementation of infection prevention measures based on the characteristics of the Omicron variant

1. 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.

• In many areas, the numbers of persons who are positive for the COVID-19 and in close contact with infected individuals are increasing at schools, kindergartens, nursery schools, etc. In addition to thorough measures to prevent infections in children, it is necessary to thoroughly implement infection control measures, including the active promotion of vaccination of teachers, childcare workers, etc. It is important to establish an environment where children and workers can take a leave of absence, in the case of any poor health conditions. It is also necessary to consider securing educational opportunities through multiple measures, including staggered attendance and online lessons, and maintaining social functions. At the same time, infection control measures must be thoroughly implemented at home. During spring breaks, thorough infection control measures are also required during tutoring/coaching at schools.
• It is important to take thorough measures at nursing care facilities, in order to control infections in the elderly. Therefore, promotion of booster vaccinations for residents and staff, as well as aggressive testing of staff is required. For infection control and medical care at facilities, prompt external support is important.
• At workplaces, it is necessary to utilize business continuity plans, and to reduce staff attendance at workplaces and opportunities for contact by adopting telework, promoting the taking of time off, and through other measures, so that social functions can be maintained. Thorough health management, the establishment of an environment where people can take a leave of absence, and the active promotion of occupational booster vaccinations for workers are also needed.

It is essential to widely share the current infection status with citizens and business operators, and cooperate toward preventing the spread of infection.

• 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. Furthermore, it is important to receive a booster vaccination with the expectation of not only preventing aggravation/onset of the disease in individuals, but also of preventing infection in the surrounding people.
• When going out, it is necessary to avoid situations/places with a high risk of infection such as crowds, and large gatherings either with or without shouting/loud speaking in poorly ventilated spaces. 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 carried out in a small group, without speaking to the extent possible, in principle, and the wearing of masks should be ensured 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 government policy.
• From the end of the current fiscal year to the beginning of the next fiscal year, there will be more opportunities for many people to gather, such as graduation ceremonies, spring breaks, three-day holidays, and cherry blossom viewing. Since the spread of the infection has been triggered by such opportunities in the past, infection control measures must be thoroughly implemented to prevent a future rebound. In addition, attention should also be paid to the fact that movement of people and training will become more frequent at the beginning of the fiscal year, as people will be newly joining companies and entering schools.

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