When will the "7th wave" of the new coronavirus end?
The number of infected people is at a record high in various places, but the pace of increase is slowing.
There is also a view that the peak is approaching.
I asked an expert for his opinion.
The latest infection status
The number of infected people nationwide reached a record high of more than 249,000 on August 3.
The weekly average is over 210,000 people per day as of the 4th.
The pace of increase compared to the previous week was
▽
2.13 times on July 14th,
1.72 times on July 21st, and
1.67 times on July 28th
.
Until now, it has decreased to 1.11 times.
The peak of the “seventh wave” is being discussed at the expert meetings
At a press conference held after the meeting on July 27, Takaji Wakita, chairman of the Ministry of Health, Labor and Welfare's expert panel, said, "There are various views about when the peak will be. There is also a view that it will continue, and there is also a prediction that the peak is approaching."
Has the effective reproduction number of infection fallen below "1"?
Professor Hiroshi Nishiura of Kyoto University says that he believes that the BA.5 strain of the Omicron strain, which is estimated to account for most of the infected people, has probably reached its peak.
Professor Nishiura used the data up to July 30th to submit an analysis of the infection status of "BA.5" in Tokyo to the expert meeting on August 3rd.
As a result of analyzing how the pace of the spread of infection changes as the number of people who become immune to the virus increases in addition to those who have been vaccinated and become immune, one person spreads the infection to how many people. The effective reproduction number, which indicates whether or not, began to decline toward the end of July, and is believed to have fallen below "1" on July 30.
This means that the number of infected people will be less than 1, and it is predicted that the number of infected people will decrease in the future.
Professor Nishiura said, "The epidemic of the 'BA.5' lineage is thought to have peaked for a while. However, as we approach the Obon Festival, when people move more due to travel, etc., a temporary increase is possible. As the number of infected people is increasing, I think that medical care will continue to be tight and the situation will continue to be difficult."
AI prediction peaks on “August 6th”
Professor Akimasa Hirata of Nagoya Institute of Technology is using AI (artificial intelligence) to simulate future changes in infection status based on data such as changes in the number of infected people, the effects of vaccines, and the flow of people.
AI predicted that the number of infected people in Tokyo would average about 39,000 per day on August 6, and that it would start to decline after that.
In addition to immunity by vaccination, it is thought that a certain number of people will decrease by acquiring immunity by infection.
However, the calculation result shows that the number of infected people per day will continue to be around 26,000 even at the end of August. Even if the peak is over, don't worry and take infection control measures."
Need to assess the impact of BA.2.75
In addition, it has been reported in India and other countries, and there is concern that one of the Omicron strains, BA.2.75, has the property of “immune escape” that evades the immunity obtained by vaccines and infections. It has been pointed out that it is necessary to assess whether it will have an impact.
"BA.2.75" has also been detected in Japan, and Dr. Wakita, chairman of the expert meeting, said at the expert meeting on August 3, So, there was an argument that the rate of decline of the 7th wave could be very slow."
According to Professor Nishiura's group, analysis based on Indian data from May to July suggests that the effective reproduction number of "BA.2.75" is 1.14 times that of "BA.5."
Professor Nishiura said that the easiness of spread compared to previous viruses was ``only minor'', and while expressing the view that ``BA.2.75'' is unlikely to spread rapidly, he said, ``BA. 2.75” is relatively easier to spread, so it is expected that it will be replaced over time.When considering what the infection situation will be in the future, it is important to investigate the speed of replacement.” pointed out.
Expert “On the verge of surviving the 7th wave”
Professor Kazuhiro Tateda of Toho University, who is a member of the government's subcommittee on countermeasures against the new coronavirus, said in an interview with NHK on August 5, "The situation is still severe, but the speed of There are areas where the spread of infection is approaching its peak, such as the Greater Tokyo Area, etc. It will be necessary to monitor trends for a week or two to see whether the peak will continue and decline, or whether the situation will remain high. I think that it is gradually becoming clear that we can overcome this without imposing strong restrictions on behavior.We are at the brink of whether we can really survive.
On the other hand, he also points out, ``In metropolitan areas, tests cannot keep up, and there is a possibility that the apparent number of infected people will not increase, causing a ``ceiling effect'' that may look like a peak, so we must be careful.''
He continued, "We are currently on summer vacation and will be approaching Obon. We have seen an increase in the number of infected people when there are more opportunities for contact between people and increased risk. Once again, each of us is a basic infection. It's important to take action with a firm awareness of the countermeasures once again.In order to prevent people who are unwell from forcing themselves to travel, I would like people with signs of infection to refrain from traveling this time." said.