84th meeting of the COVID-19 advisory boardof Ministry of Health, Labour and Welfare (May 19, 2022). Material 1

Evaluation of the latest infection status, etc.

Infection status

• Nationwide, the number of new cases of infection (by date of report) is about 203 per 100,000 in the last week, showing a ratio to the previous week of 1.07, but recently the moving average for last week is on a decreasing trend, lower than the level before Golden Week, which had been on a decreasing trend. Since Golden Week also affects the values, it is necessary to pay close attention to future movements.
• The number of new cases of infection by age group slightly increased or increased in all age groups, with a marked increase particularly among those in their 20s (2nd week in May vs. 1st week in May).
• With the number of new cases of infection starting to increase nationwide, the number of patients being treated also tends to increase. On the other hand, the number of severe cases continues to decrease, and the number of deaths has leveled off.

  Effective reproduction number: On a national basis, the most recent number is below 1, at 0.97 (as of May 1). The figure stands at 0.94 in the Tokyo metropolitan area and 0.97 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.

1. Hokkaido

   The number of new cases of infection is approximately 346 (approximately 402 in Sapporo City), with a ratio to the previous week of more than 1 (1.07). The individuals are mainly in their 20s or younger. Numbers in all age groups are increasing; particularly, those in their 20s have increased markedly. The use rate of beds is approximately 20%.

2. North Kanto

   In Ibaraki, the number of new cases of infection is approximately 134, with a ratio of this week to last week of more than 1 (1.08). The individuals are mainly in their 20s or younger. In particular, the increase among those in their 20s is marked. The use rate of beds is approximately 10%. In Tochigi and Gunma, the numbers of new cases of infection are approximately 135 and 128, respectively, with a ratio of this week to last week of less than 1 (0.89 and 0.92). The use rates of beds are slightly more than 10% in Tochigi and approximately 20% in Gunma.

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

   The number of new cases of infection in Tokyo is approximately 184, with a ratio of this week to last week of 1.0. The individuals are mainly in their 20s or younger. Numbers in all age groups are slightly increasing or increasing; particularly, those in their 20s have increased markedly. The use rate of beds and the use rate of beds for severe cases are both slightly more than 10%. In Chiba, the number of new cases of infection is approximately 112, with a ratio of this week to last week of 1.0. In Kanagawa, the number of new cases of infection is approximately 144, with a ratio of this week to last week of more than 1 (1.08). In Saitama, the number of new cases of infection is approximately 136, with a ratio of this week to last week of less than 1 (0.97). The use rates of beds are about 20% in Saitama, about 10% in Chiba and slightly less than 20% in Kanagawa.

4. Chukyo/Tokai

   In Aichi, the number of new cases of infection is approximately 206, with a ratio of this week to last week of more than 1 (1.13). The individuals are mainly in their 20s or younger. Numbers in all age groups are increasing; particularly, those in their 10s and 20s have increased markedly. The use rate of beds is approximately 20%. In Gifu, Shizuoka and Mie, the ratios of this week to last week are more than 1 (1.09, 1.32, and 1.08, respectively), with the number of new cases of infection at approximately 200, 190, and 161. The use rates of beds are about 30% in Gifu, slightly more than 10% in Shizuoka, and slightly less than 20% in Mie.

5. Kansai area

   In Osaka, the number of new cases of infection is approximately 236, with a ratio of this week to last week of more than 1 (1.06). The individuals are mainly in their 20s or younger. Numbers in all age groups are increasing; particularly, those in their 20s or younger have increased markedly. The use rate of beds is approximately 20%. In Shiga, Kyoto, Hyogo, Nara, and Wakayama, the numbers of new cases of infection are 181, 233, 194, 159, and 188, respectively, with a ratio of this week to last week of more than 1 (1.19, 1.13, 1.13, 1.22, and 1.06). The use rates of beds are slightly more than 10% in Shiga, Kyoto, and Nara, about 20% in Hyogo, and slightly less the 30% in Wakayama.

6. Kyushu

   In Fukuoka, the number of new cases of infection is approximately 269, with a ratio of this week to last week of more than 1 (1.01). The individuals are mainly in their 20s or younger. Numbers in all age groups are slightly increasing or increasing; particularly, those in their 20s have increased markedly. The use rate of beds is approximately 20%. In Kumamoto and Miyazaki, the numbers of new cases of infection are approximately 238 and 325, respectively, with a ratio of this week to last week of more than 1 (1.11 and 1.13). In Saga, Nagasaki, Oita, and Kagoshima, the numbers of new cases of infection are approximately 230, 215, 226, and 288, respectively, with a ratio of this week to last week of less than 1 (0.80, 0.94, 0.99, and 0.97). The use rates of beds are slightly more than 20% in Saga, Nagasaki, Kumamoto, and Miyazaki, approximately 20% in Oita, and slightly more than 30% in Kagoshima.

7. Okinawa

   The number of new cases of infection is the highest nationwide, at approximately 1014, with a ratio of this week to last week of more than 1 (1.13). The infected individuals are mainly in their 30s or younger. Numbers in all age groups are increasing; particularly, those in their 30s or younger have increased markedly. The use rate of beds is slightly more than 50%. The use rate of beds for severe cases is slightly more than 20%.

8. Areas other than the above

   In Iwate, Akita, Fukushima, Ishikawa, Nagano, Okayama, Hiroshima, Yamaguchi, Kagawa, and Kochi, the numbers of new cases of infection are approximately 151, 140, 182, 300, 146, 252, 301, 164, 252, and 267, respectively. The use rates of beds are slightly more than 20% in Iwate, Akita, Ishikawa, Nagano, Okayama, Yamaguchi, Kagawa, and Kochi, slightly more than 30% in Fukushima, and about 30% in Hiroshima.

Future outlook and measures to be taken

• Infection status

  • Regarding the number of new cases of infections, the moving average for last week has been on a decreasing trend in the past few days, except in some areas. However, it is still difficult to accurately evaluate the infection status due to the influence of Golden Week on the figures. By region, the moving average for last week is lower than the peak of last summer in the Tokyo metropolitan area. In contrast, the moving average for last week is higher than the peak from the end of last year in Okinawa and Miyazaki. In particular, the number of new cases of infection in Okinawa is the highest nationwide, and the highest ever, with the increasing trend still continuing. In other regions as well, it will be necessary to continue to pay attention to changes in the number of infected people.

  • The number of new cases of infection by age group slightly increased or increased in all age groups, particularly among those in their 20s nationwide, and there were also marked increases in many areas. In Okinawa, the number of new cases of infection continues to increase in all age groups. Particularly, the number of young people in their 30s or younger is markedly increasing, and the number of elderly people in their 60s or older is also greatly increasing. The infection status in the elderly must be carefully monitored in other regions.

  • The proportion of new cases of infection at schools has increased after the end of Golden Week. In addition, due to the emphasis on epidemiological surveys, a trend of increased infections in eating and drinking places is not always clear, but caution is required because the number of infected people in the younger generation is increasing.

  • As for the future infection situation, it may be affected by factors that increase infections, such as active movements of people during Golden Week and the ongoing substantial replacement by the BA.2 lineage, as well as factors that suppress infection, such as a third vaccination, etc. In addition, since the number of infected people in the younger generation continues to increase, continuous attention to future trends is necessary.

• Factors that increase and suppress infection

  1. The infection status is affected by the following factors, which increase or suppress infection. However, it will be necessary to continue to pay close attention to the infection status, for some time in the future.

  1. [Contact patterns]

     While there are areas where the nighttime population started to increase after Golden Week, mainly in metropolitan areas, there are also areas where the number increased sharply beyond the peak at the end of last year during Golden Week, but started to decrease afterward, and there are regional differences. In addition, it is necessary to pay attention to the influence on the future infection status due to active movement of people and an increase in opportunities for contact during Golden Week.

  2. [Epidemic strain]

     The replacement by the BA.2 lineage has generally progressed and compared to the time when the BA.1 lineage was dominant, it may be a factor in the increase in the number of newly infected individuals and the slowdown in the decrease.

  3. [Vaccinations, etc.]

     The main purpose of a 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. However, it should be noted that as a certain period elapses after the third vaccination, the preventive effect against infection is expected to diminish from those who received vaccination earlier. In addition, the retention of immunity due to previous infections may affect trends in occurrence, by region.

  4. [Climate factors]

     As the temperature will rise day by day, it will become easier to ventilate, due to climate conditions. However, elevated temperatures and rainfall may increase indoor activities.

• Medical care provision system

  • In Okinawa, the number of inpatients and the use rate of beds continue to increase, and the use rate of beds for severe cases remains at the 20% level. In other regions, the use rate of beds and the numbers of home care recipients and medical treatment adjustments have increased, with the exception of some areas.

  • As for cases of difficult emergency transportation, the national total is lower than the peak in the summer of last year, but there is a tendency for it to stop declining. The number is increasing in some regions regardless of the increase or decrease in the number of infected people, showing regional differences.

• Efforts based on the spread of infection with the Omicron variant

  1. [Surveillance, etc.]

     It is necessary to consider effective and appropriate surveillance, in order to properly grasp trends regarding occurrences. In addition, it is necessary to continue monitoring the trends of variants through genomic surveillance. For severe cases, clusters, and other applicable cases, confirmation via PCR testing for mutant strains and a whole-genome analysis is required.

  2. [Efforts by local governments]
     • Local governments also need to inspect the medical care/testing system and the public health center system in order to strengthen the response based on the characteristics of 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 deaths that occurred at home after January of this year, approximately 80% of the patients have been aged 70 years and older, which is similar to the trend of all deaths during the same period, suggesting that many patients die from factors other than the novel coronavirus. The vaccination rate in these fatal cases was confirmed to be a certain number of those who had completed the second vaccination, due to the progress of vaccination in Japan. Local governments are trying to speed up efforts to make contact with infected persons who are at a high risk of becoming severely ill, and it is important to continue to make efforts to provide the necessary medical care to home care recipients.
  3. [Reinforcement of information provision to unvaccinated individuals and those receiving a third vaccination, etc.]
     • As of May 18, the rate of third vaccinations was about 89% for the elderly aged 65 years and older, and about 57% overall. Vaccination of elderly persons is expected to reduce the risk of severe illness and death. In order to minimize the number of severe and fatal cases, and to reduce the number of patients with symptoms to the lowest possible level, it is necessary to steadily implement a third vaccination in subjects, and to vaccinate as many desiring recipients as possible. As for a fourth vaccination, it is necessary to provide appropriate guidance on vaccination based on the fact that it will be implemented from the end of May as a special temporary vaccination for persons aged 60 years or older, persons with underlying diseases at high risk of severe symptoms, and other persons deemed by doctors to be at a high risk of severe symptoms, in order to prevent such symptoms.
     • 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. Therefore, 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.
  4. [Quarantine measures]

     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.

• 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 the Omicron variant.

  • In schools, kindergartens, nursery schools, etc., it is necessary to make efforts to continue educational activities as much as possible, after reconfirming and thoroughly implementing infection control measures, including active promotion of vaccinations for teachers and nursery teachers, as well as thorough implementation of infection control measures for children, while sharing situations where the risk of infection in children and students increases with staff, children, parents, 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, thorough infection control measures are also required at home.
  • It is necessary to take thorough measures at nursing care facilities, in order to control infections in the elderly. Therefore, promotion of a third vaccination for residents and staff, as well as aggressive testing of staff is required. In addition, it is important to secure external support systems for infection control and medical care at facilities, and to promptly intervene when infection is confirmed at facilities.
  • 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 third 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 the infection.

  1. Although it is difficult to make an accurate assessment of the current infection status due to the influence of Golden Week, it is still higher nationwide than the peak last summer. For this reason, it is necessary for citizens and businesses to cooperate to maintain the decreasing trend in the number of infections, and to call for thorough basic measures against infection and daily health management, in order to prevent a resurgence in the number of new cases of infection.

  2. [Vaccination]

     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.

  3. [Thorough infection control]

     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.

     On the other hand, it is not always necessary to wear a mask as before if it is possible to secure sufficient distance from surrounding people outdoors, or even when it is not possible to get sufficient distance from the surrounding people outdoors if there is little (or almost no) conversation. However, it is still necessary to wear them outdoors in a crowd. After clarifying that not all preschoolers are required to wear masks, and that they shall not be forced to wear them, the information should be disseminated widely and thoroughly.

  4. [When going out]

     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.

  5. [Health management]

     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.

<< Reference: 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 adhering to mucosa, aerosol inhalation, contact infection, etc.).

3. [Severity]

   It has been suggested that infection with the Omicron variant presents a lower risk of hospitalization or aggravation than the Delta variant. However, analyses to date show that the fatality due to infection with the Omicron variant is higher than that due to seasonal influenza. 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.

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 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.

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 a third vaccination restores the infection-preventing effect, onset-preventing effect, and hospitalization-preventing effect against infection by the Omicron variant, as well as information regarding how these vaccine effects are attenuated after a third vaccination.

6. [BA.2 lineage]

   Overseas, the number of infected patients has increased, while replacement with the BA.2 lineage is progressing. However, the number is currently decreasing worldwide. In Japan, the influx of the Omicron variant from overseas initially comprised both BA.1 and BA.1.1; however, BA.1.1 has since become dominant. Currently, it has been largely replaced by the BA.2 lineage. 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.

7. [XE, BA.4, BA.5, and BA.2.12.1 lineages]

   The XE lineage of the Omicron variant is a recombinant of the BA.1 and BA.2 lineages of the Omicron variant. Two cases of the XE lineage were identified in quarantine. The WHO report indicated that the rate of increase in community-acquired infections was approximately 10% higher than that of the BA.2 lineage. In addition, one case of the BA.4 lineage and two cases of the BA.5 lineage were confirmed in quarantine. In some countries and regions, the detection rates of the BA.4, BA.5, and BA.2.12 1 lineages have increased, and the BA.2 lineage has been replaced by these variants, suggesting its superiority in terms of an increase in the number of infected patients. The National Institute of Infectious Diseases has suggested 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)