ASOURCE Navi

The number of new infections with the new coronavirus infection has increased again, and it is said that it has entered the 7th wave. Possible reasons for this include a decrease in the preventive effect against infection due to the passage of time after vaccination, relaxation of restrictions on movement, and insufficient indoor ventilation due to the use of air conditioners. is also a major factor. We have summarized the infectivity of BA.5, symptoms, vaccine effects, etc.

The number of people infected with the new coronavirus has continued to increase nationwide in July, more than doubling from the previous week. Under these circumstances, the highly contagious Omicron strain BA.5 is spreading nationwide. BA.5 is a type of Omicron strain that was discovered in South Africa in February 2022, spread mainly in Europe from May, and accounts for about 50% of all new coronaviruses detected worldwide since June. . In Japan, BA.2, which was the mainstream in April, has been replaced by BA.5, and according to an analysis by the National Institute of Infectious Diseases, it is expected to reach almost 100% nationwide in early August.

A UK Health Security Agency report estimates that BA.5 spreads 35.1% faster than BA.2. BA.5 has mutations ``L452R'' and ``F486V'' in the spike protein on the surface of the virus, and is characterized by avoiding immunity caused by vaccination and past infections. For this reason, even if you are vaccinated, it is thought that you will be more susceptible to infection than the Omicron strain so far. It has been confirmed that the antibody concentration produced by vaccination drops to about a quarter of the peak after six months or more. The third inoculation is progressing, but it is thought that the acquired immunity will weaken over time. According to a trial calculation made by Professor Hiroshi Nishiura of Kyoto University, as of July 13, the percentage of people with immunity to Omicron strain BA.4 and BA.5 was 31.2% for those in their 20s, 30.2% for those in their 30s, and 40. 29% in their 50s, 29.7% in their 50s, 26.4% in their 60s, and 26% in their 70s and over.

Regarding the degree of severity of BA.5, according to the WHO report, there is no evidence that it is more likely to become severe than Omicron strain BA.1, which was the first outbreak. BA.2 is considered to have the same rate of aggravation as BA.1, so BA.5 is considered to have the same aggravation rate as BA.2.

In the 6th wave, many patients complained of sore throats, but the symptoms of patients who visited in July tended to be a high fever of 38 ° C or higher and complaints of malaise. will be In addition, about half of travelers from overseas who have BA.5 are asymptomatic. The number of infected people in the 50s and younger age group has increased significantly, and the number of severe cases and the number of deaths have remained at low levels.

The number of BA.5 infections is rapidly increasing around the world, but Portugal is attracting attention as a country where BA.5 was quickly brought under control. In May of this year, the replacement with BA.5 progressed, and the number of infected people increased to a record high in late May, but the number of severe cases and the number of hospitalized people were the lowest ever, and it is said that it started to decrease in a short period of time after that. increase. The proportion of elderly people in Portugal is as high as in Japan, and the vaccination situation is said to be similar to that in Japan.

The government has announced that it will expand the target of the fourth vaccination of the new corona vaccine, which is currently provided to people aged 60 and over and people aged 18 and over with underlying diseases, to medical workers and workers in facilities for the elderly. Did. Regarding the effect of the 4th vaccine, according to an Israeli research report, during the Omicron strain epidemic, the Pfizer vaccine 4-dose group (January 3-February 18, 2022) for people aged 60 and over received 3 doses Thirty days after inoculation, the efficacy was 45% for infection prevention, 55% for onset prevention, 68% for hospitalization prevention, 62% for severity prevention, and 74% for death prevention. is shown.

Regarding the current medical care system, although the hospital bed occupancy rate is generally low nationwide, it is on the rise in some areas, including large cities, due to the increase in the number of new infections. The government's new corona subcommittee has shown the idea of dividing measures into five levels with a greater emphasis on "degree of medical emergency", but as of July 14, many prefectures are at level. It is judged as 2 (strengthened vigilance). In the future, the rapid spread of infection will have a considerable impact on the medical delivery system, and experts will need to flexibly utilize hospital beds, including temporary medical facilities, according to the severity and age of patients. And so on.