Omicron strain, a mutant virus of the new coronavirus that is said to be more infectious than the Delta strain.
While hard border measures are being taken, community-acquired infections have been confirmed one after another in Japan, and there are concerns about further spread of the infection.
Will Omicron strains lead to the so-called "sixth wave" of fashion?
What should we do to curb the "sixth wave" during the New Year holidays, when the infection is most likely to spread?
Prediction of the number of AI infected people The peak is ...
As the infection of Omicron strains spreads all over the world, what will happen to the infection of the new coronavirus when Omicron strains enter the country?
Professor Akimasa Hirata of Nagoya Institute of Technology makes predictions using AI = artificial intelligence.
The Omicron strain was first announced by South African authorities on November 25, 2021.
There are many things I don't understand yet.
Professor Hirata reports on how the number of people infected with the new coronavirus in Tokyo changes depending on the time when the community-acquired infection of the Omicron strain begins, data on the flow of people to AI, changes in past infections with the new coronavirus, and so far overseas. Data on the infectivity of the Omicron strain and the effect on the effect of the vaccine were input and analyzed.
Assuming that the community-acquired infection of Omicron strains began in Tokyo on December 25, the number of new infections per day in Tokyo was calculated to peak at about 3,300 in mid-February. ..
Even assuming that community-acquired infections began on January 1, 2022, the number reached 3,000 in mid-February.
If it could be delayed until January 16, 2022, the daily number of infected people in Tokyo would be up to 2200 in early March.
Professor Hirata
"I think that the fact that the onset of community-acquired infections was suppressed until at least the latter half of December is the result of border measures. If community-acquired infections started in early December, the year-end party season and the spread of infection overlap. I think the number of infected people has increased considerably. "
The AI forecast includes all new coronas such as Delta strains as well as Omicron strains.
However, the result was that when the spread of the Omicron strain began, it would have a great impact on the subsequent infection status.
Is it the "6th wave" as it is?
"In my experience ..."
In Tokyo, an infected person who seems to be a community-acquired Omicron strain was confirmed on December 24th.
Will it become a trendy wave, the "sixth wave", if nothing is done?
Professor Hirata
"If AI goes according to expectations, it may be a big wave in our experience so far. However, the prediction will change depending on our future actions, so we need to take proper infection control measures. I think this number can be reduced by about 20%. I think it is important to act with moderation. "
"When you start expanding, the speed is fast."
Apart from AI predictions, ongoing virus research around the world is gradually revealing the nature of the Omicron strain.
Experts are concerned about the infectivity of Omicron strains and their impact on vaccine efficacy.
Takaji Wakita, chairman of the Ministry of Health, Labor and Welfare's expert meeting, gave his views on the Omicron strain at a press conference after the meeting held on December 22, 2021.
Chair Wakita
"It is time to assume that the spread of infection by Omicron will occur in Japan. There have been various discussions among experts, but when the Omicron strain begins to spread, the speed is fast. However, it is known from the overseas epidemic situation. If it expands at the same speed in Japan, the medical care provision system will be rapidly tightened, so it is necessary to prepare for it. "
Chair Wakita
"While the Omicron strain is highly infectious, it is becoming clear that the number of mildly ill and asymptomatic people increases when infected. Secure accommodation facilities and observe the health of people who receive medical treatment at home or institution. it will be necessary to have a system in place. in addition, it is important that as a response to that vaccine efficacy is lowered to proceed with the ahead of schedule of the additional vaccination. "
epidemic by Omicron Corporation" sixth wave "is Regarding the possibility of this happening ...
Chair Wakita
"It was hard to think that the immunity effect of delta strains would be maintained by vaccination, etc., and that it would lead to a major epidemic soon, but the effect of vaccines would decrease in omicron strains. The situation in other countries can lead to very rapid infections. Today's human-to-human contact opportunities have risen to the same level as last year's most frequent times. It seems that the epidemic is in a situation where it can start at any time. "
Omicron strain What is the speed of infection?
What is the infection speed of the Omicron strain, which many experts point out?
Looking at the example of England ...
The Omicron strain was first identified in the United Kingdom on 27 November.
About a month later, on December 24, the number of people confirmed to be infected with the Omicron strain in Japan was more than 23,700 a day, and the cumulative total was about 114,000 (December). Data as of 24th).
On December 23, 2021, Shigeru Omi, chairman of the Coronavirus Omicron Infectious Disease Control Subcommittee, announced the "doubling time" of Omicron strains (the period required for the cumulative number of infected people to double) in the United Kingdom and South Africa. An analysis of endemic areas pointed out that there were "reports that it was extremely short, 2 to 3 days."
According to the materials presented by a group of Professor Hiroshi Nishiura of Kyoto University and Professor Kimito Ito of Hokkaido University at an expert meeting of the Ministry of Health, Labor and Welfare on December 22, 2021, "effective reproduction" of Omicron strain calculated from Danish data. The number (a number that indicates how many people one person spreads to) was 3.19 times that of the Delta strain.
Is the vaccine effect decreasing?
Another concern is that the vaccine may be less effective against the Omicron strain.
Professor Nishiura explains how many people in Japan currently have sufficient immunity to the Omicron strain, based on overseas research investigating the effects of Pfizer's vaccine on the Omicron strain and domestic vaccination data. I estimated if it was there.
As a result, at the time 2021 December 22,
the people there is a level of immune 14.8% that can prevent the onset ▽
people that there is a level that it is possible to prevent the ▽ severe immune 38.7%
it is possible to avoid the ▽ death It means that 37.5% of people have a level of immunity.
The vaccination rate in Japan is about 80%, but this is the current state of immunity to the Omicron strain.
Professor Nishiura says that immunity to the Omicron strain seems to be inadequate to prevent the "sixth wave" epidemic.
Professor Nishiura
"Overseas, large-scale clusters have started to occur overseas, mainly among young people at nightclubs, Christmas parties, and live concerts. In Japan, when such high-risk contact indoors occurs, clusters occur. I want the citizens, the government, and the government to share the same awareness of the risks of the Omicron stock. I want you to think about the risks associated with returning home and moving during the year-end and New Year holidays. "
A strong sense of caution against the bleeding "6th wave"
尾身会長は12月23日に会見を開いてオミクロン株への警戒を呼びかけました。
オミクロン株の市中感染については今のところスポット的に起きているもので面的な広がりまでは至っていない可能性を指摘しましたが、呼びかけの中では今後の「第6波」に対する強い警戒感をにじませました。
尾身会長
「年末年始の時期を迎え、デルタ株も感染拡大の傾向にある。今後ある程度の感染拡大は覚悟しなければならない。過去の変異ウイルスの経験を振り返っても、オミクロン株は国内の複数の場所で感染が起きていることは間違いない。オミクロン株に対しては、ワクチンの感染予防効果が弱まることが分かっているうえに感染拡大のスピードが極めて速い。日本でも急速な拡大が起こる可能性がある」
Chairman Omi
"Once the Omicron strain has become established in the community, even if there are many mildly ill people, the medical system may not be able to respond to the rapid increase in infected people. However, there was a time lag before the elderly became infected and the number of severely ill people began to increase. It is essential to make a decision to hit a strong timing even earlier than before. ”
Regarding the year-end and New Year actions ...
Chairman Omi:
“ Although the number is increasing at the moment, the level of infected people is quite calm. That's a message that many people don't sympathize with or understand. However, if you're still wondering whether to go home or travel, take a look at the situation with Omicron strains and think a little. As an expert, I have a responsibility to tell you that the infectivity of Omicron strains is different from the past, and that there is a risk that contact opportunities will increase and infections will increase toward the end of the year, and that it will spread to various places by returning home. I think that how you spend your time will affect how the infection spreads in the future. "