The number of people infected with the new coronavirus per day exceeded 10,000 in Tokyo for the first time in about four months, and exceeded 90,000 nationwide.
It is thought that one of the Omicron strains, "BA.5", is greatly involved in the current re-expansion of infection.
What is the peak of infection?
What about vaccines?
How severe is it?
I have summarized the latest views.
"7th wave" "BA.5" becomes mainstream
Infection with the new coronavirus, which has been on a downward trend since February, has been spreading again since the end of last month.
On the 11th of this month, Chairman Omi of the government subcommittee said, "There is no doubt that a new wave of infection has arrived," and expressed the recognition that it has entered the "7th wave."
Experts say that the background of the re-expansion, which can be said to be the "7th wave", is that
the effects of immunity obtained by vaccination and infection so far are weakening over time,
and that contact between people ▼ Among the Omicron strains, "
BA.5
", which is said to have stronger infectivity, may be becoming the mainstream.
What is "BA.5" in the first place?
What is the infectivity?
"BA.5" is a type of Omicron strain, which was confirmed in South Africa in February and then spread mainly in Europe and the United States after May.
Currently, most of the new coronaviruses detected in the world are Omicron strains, but according to WHO = World Health Organization, "BA.5" will be in the week until June 25, an increase of 15 points from the previous week. It accounts for 52%.
In the United States, the week leading up to July 9 accounts for 65% of the total.
WHO Secretary-General Tedros said at a press conference on Wednesday that "a new wave is emerging and it is once again shown that the new Corona is not nearing its end."
According to a statement released by the British health authorities on the 24th of last month, "BA.5" is expected to spread 35.1% faster than "BA.2".
It is beginning to spread in Japan, and according to the material presented by Professor Hiroshi Nishiura of Kyoto University at the expert meeting of the Ministry of Health, Labor and Welfare on the 13th of this month as a result of analysis based on the data in Tokyo, "BA.5" is It is estimated that it is spreading 27% faster than the mainstream "BA.2".
According to a report at the monitoring meeting in Tokyo, 33.4% of the cases were suspected of having "BA.5" in the week leading up to June 27, and the replacement is progressing.
In addition, according to the analysis of the National Institute of Infectious Diseases, the proportion of "BA.5" is estimated to be almost 100% nationwide in the first week of August.
What is the peak of infection?
Predicted by AI
Professor Akimasa Hirata of Nagoya Institute of Technology shows the results of prediction of the number of infected people and deaths in the future analyzed using AI = artificial intelligence.
According to this, assuming that the infectivity of "BA.5" is 1.3 times higher than before, we analyzed it based on data such as changes in the number of infected people in the past, the effects of vaccines, and the flow of people. The number of infected people peaked on the 25th of this month, resulting in about 18,000 people a day.
In Tokyo, the number of elderly people aged 65 and over who die is estimated to be about 20 per day in August, but the fourth inoculation, mainly for those aged 65 and over, is going well. If we proceed, it is said that the calculation result will be reduced to about 10 people in late September.
Atsuro Hamada, a specially appointed professor at Tokyo Medical University who is familiar with infectious diseases, said, "Given that many people have been vaccinated for the third time and it is not cold, the Omicron strain will be released at the beginning of this year. It is possible that the number of infected people will not increase as much as when the epidemic began, but measures should be prepared in anticipation of an increase beyond what was previously experienced. The third vaccination has not yet been received. People want to get it early, and it is most important for elderly people to get a fourth vaccination. "
In addition, "When the number of infected people is particularly increasing, it is important to take preventive measures for each person to some extent, and if there are symptoms that suggest infection, we should test early or consult a medical institution. In many areas, the sickbed is not yet tight, but I would like the government agencies to prepare in advance and consider a fourth vaccination for medical staff and staff of nursing homes. " I complained.
What about vaccines?
Regarding the vaccine, the British health authorities analyzed the data of people infected during the month or so until the end of May in a report issued on the 24th of last month, and found that people infected with "BA.5" It is reported that the effect of the vaccine was not significantly different from the effect on people infected with "BA.2".
On the other hand, the FDA = Food and Drug Administration in the United States announced on the 30th of last month that booster vaccines to be given after this fall will be "BA.4" and "BA.5" in addition to the components of the vaccine currently in use. It announced that it recommended to pharmaceutical companies that it should develop a product with a booster protein added.
However, the current vaccine is said to be the basis for preventing the disease from becoming severe when infected with the new corona, and it does not require changes to the current vaccination.
Professor Hamada of Tokyo Medical University said, "Even in Japan, the spread of infection after autumn may be more serious than it is now. Discussions on the concept of inoculation after autumn and securing vaccines at the national level Should be advanced. "
The immunity gained from vaccination and infection ...
In addition, the immunity gained by vaccination and infection has weakened over time, which is believed to have contributed to the spread of the infection.
According to the estimation data presented by Professor Nishiura of Kyoto University at the expert meeting of the Ministry of Health, Labor and Welfare on July 13, the percentage of people who are immune to "BA.4" and "BA.5" of the Omicron strain will be. It means that it is falling even in the age of.
As of the 13th, the percentage of people with immunity was 31.2% in their 20s, 30.2% in their 30s, 29% in their 40s, 29.7% in their 50s, 26.4% in their 60s, 26% in their 70s and above, etc. It has become.
Is it easy to get serious?
WHO stated in its weekly report on July 6 that "there is no evidence that the severity has changed compared to'BA.2'" as to whether it is more likely to become severe if infected.
However, as the number of infected people has increased in multiple countries, the number of people who have been hospitalized or treated in the intensive care unit, and the number of people who have died, are increasing rapidly.
The ECDC = European Centers for Disease Control and Prevention also said, "There is no evidence that the severity is increasing," and pointed out that as the number of infected people increases, the number of hospitalizations and deaths may increase. I am.
According to a paper published on the Internet by a group of Professor Yoshi Sato of the University of Tokyo before being peer-reviewed, a virus produced by reproducing the characteristics of "BA.5" was infected with a hamster. It means that I lost about 10% of my weight.
"BA.2" did not lose weight, while "BA.5" showed more inflammation such as lungs, which may be more pathogenic than the conventional Omicron strain. It is said that.
In fact, due to the effects of the vaccines I have received so far, the symptoms of infection with "BA.5" are not yet clear.
Professor Hamada of Tokyo Medical University said, "At the moment, it is thought that'BA.5'will not cause so much severity, but it is not clear yet. In France, Italy, Germany, etc.," It has been replaced by "BA.5", and the number of infected people has increased considerably in the past one or two weeks. How the number of infected people will change and how much the number of severely ill people will increase in these countries is It is considered to be very important in predicting the situation in Japan in the future. "
The characteristic of escaping immunity
"BA.5" is a protrusion on the surface of the virus, and mutations called "L452R" and "F486V" have occurred in the "spiked protein" that serves as a foothold when infecting cells.
It is believed that these mutations have led to the property of "BA.5" to escape immunity.
According to WHO, there is an experimental result that the effect of the neutralizing antibody that suppresses the action of the virus of "BA.5" is less than one-seventh of that of "BA.1" that initially spread.
In addition, according to a paper published in the scientific journal "Nature" on the 5th of this month by a group of Columbia University in the United States, "BA.4" was found in an experiment using blood of a person who had been vaccinated with the new Corona mRNA vaccine three times. And "BA.5" means that the effect of the neutralizing antibody was less than one-fourth that of "BA.2".
Even more worrisome mutant viruses
Kobe City announced yesterday that a type of Omicron strain "BA.2.75" was detected for the first time in Japan other than quarantine.
It is a mutant virus first reported from India in June, and has also been found in the United Kingdom, Germany, and the United States.
Like "BA.5", it has the property of escaping immunity, and in India, it increases faster than "BA.5".
Professor Hamada said, "WHO is also paying close attention to the fact that it is easier to escape immunity than the mainstream" BA.2 "so far, and it is more likely that people with immunity will be infected. I don't think you need to worry about it in Japan yet, but at the administrative level, I think it's better to monitor the characteristics of this new virus fairly closely. "