73th meeting of the COVID-19 advisory boardof Ministry of Health, Labour and Welfare (February 24, 2022). Material 1

Evaluation of the latest infection status, etc.

Infection status

• The number of new cases of infection nationwide (by date of report) decreased to about 426 per 100,000 in the last week, with the ratio of this week to last week at 0.93, but the rate of decrease has slowed down. The number of new cases of infection tended to decrease in almost all age groups, but remained at the same level in patients aged less than 10 years and those in their 80s and older.
• Among the 31 prefectures that are currently under priority preventative measures, 27 of them continued to show a downward trend in the number of new cases of infection, with a ratio of this week to last week of less than 1. However, it should be noted that in some areas, the number of patients in their 80s and older continues to increase.
• Among 5 prefectures in which the application of priority measures was lifted, Yamagata and Okinawa have a ratio of this week to last week of more than 1.
• Although the number of patients receiving treatment is decreasing along with the decrease in the number of new infections nationwide, the number of severe cases remains high and the number of deaths continues to increase.

  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.

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 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%.

2. Tohoku

   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%.

3. North Kanto

   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.

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

   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.

5. Chubu/Hokuriku

   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.

6. Chukyo/Tokai

   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.

7. Kansai area

   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.

8. Chugoku/Shikoku

   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.

9. Kyushu

   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.

10. Okinawa

    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%.

< Areas other that the above >

1. 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.

Future outlook and measures to be taken

• The number of newly infected people nationwide has continued to decrease, with the effective reproduction number and the ratio of this week to last week at 1 or less. Infections continue to occur at places such as homes, schools, nursery schools, workplaces, hospitals, and nursing care facilities. In particular, there is an increase in clusters in nursing care facilities, especially in urban areas. Although there is a decreasing trend in many regions, including areas under priority measures, the rate of decrease has slowed down, with some areas leveling off or increasing. In particular, among the 5 prefectures in which the application of priority measures was lifted, Yamagata and Okinawa again have a ratio of this week to last week that exceeded 1, and there is concern that the number of new cases of infection will increase again, including other prefectures.
• In the current situation, unlike the spread of infection last summer, which showed a continuous decreasing trend with the acceleration of vaccination, the decrease in the number of patients with new infection is slow, and it could turn to an increasing trend nationwide again. The nighttime population is increasing mainly in urban areas under priority measures, but also in areas where priority measures have been lifted. Particularly in Okinawa, the nighttime population has been increasing rapidly before the lifting of the priority measures. It is necessary to pay attention to the possibility that the number will increase again with replacement by the BA.2 lineage in the future, although there are no signs of this yet. The number of people infected with the Delta variant, which has almost been replaced by the Omicron variant and is more likely to become severe, is decreasing, but it is still detected.
• It has been pointed out that the published data on the number of positive tests may deviate from the actual situation due to delays in reporting, and it is necessary to pay close attention to other indicators.. For example, in the monitoring items in Tokyo, the number of consultations such as on fever, the number of people tested, and the number of positive tests are continuously decreasing. The number of applications of the "Tokyo Rule" for emergency medical care has been level or shown some signs of decrease, but the number of inpatients and severe cases has been leveling off from a slight increase. It is important to continuously monitor these indicators when determining the epidemic status. In the positive rate of tests, there is a marked delay in reporting the number of tests, which is the denominator, and this should just be used as a reference.
• Even if the number of infected people nationwide continues to decline, for the time being, there is a possibility that the medical care provision system for mild and moderate cases will be strained in many areas, and the use of beds for severe cases will continue to increase due to the increase in the number of elderly people with severe illness. It was suggested that the death toll from the spread of infection this time may be centered on the elderly. It has been pointed out that some of them die without meeting the definition of severe illness due to the effects of not desiring highly invasive treatment or the worsening of an underlying disease. 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 require hospitalization due to disease exacerbation by the infection, or elderly infected patients developing pneumonia, including aspiration pneumonia, even in cases where they do not have COVID-19 pneumonia.
• In cases of difficult emergency transportation, non-COVID-19 suspected cases are increasing, which puts a heavy burden on conventional medical care, especially emergency medical care.

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 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.).

3. [Severity]

   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.

4. [Duration of viral shedding]

   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.

5. [Vaccine effect]

   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.

6. [BA.2 lineage]

   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.

Efforts based on the spread of infection due to the Omicron variant

1. [Surveillance in areas where infection is rapidly spreading]

   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.

2. [Measures taken by local governments]

   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.

3. [Reinforcement of information provision to persons who are unvaccinated or who have booster vaccination]

   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.

4. [Quarantine measures]

   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.

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. Local governments need to actively promote vaccination for teachers, childcare workers, and the other staff at such facilities. 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 also be thoroughly implemented at home.
• It is important to take thorough measures at nursing care facilities in order to control infection in the elderly. Therefore, promotion of booster vaccinations for residents and staff, as well as aggressive testing for staff is required. For infection control and medical care at facilities, external support is important.
• At workplaces, it is necessary to promptly review business continuity plans, and to reduce staff attendance at workplaces and opportunities for contact by utilizing telework, promoting the taking of time off, and through other measures, so that social functions can be maintained. Thorough health management and 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 due to 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 a physician and undergo tests according to government policy.
• Towards the end of the fiscal year, events such as graduation ceremonies and spring break will be held where many people will gather. Since the spread of infection has been triggered by such opportunities in the past, infection control measures must be thoroughly implemented.

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