New Corona Omicron mutant strain vaccine is the latest information

We are entering the entrance of the 8th wave.

Experts point out:

The new coronavirus has repeated waves of infection expansion every time a new mutated virus with strong infectivity comes out.

And now, mutated viruses called "BQ.1", "BQ.1.1" and "XBB" of the Omicron strain are beginning to increase to replace the mainstream "BA.5".

What is the risk of exacerbation of new mutant viruses?

Are vaccines effective?

I have summarized what I have learned.

``BA.5'' that raged, the proportion decreased worldwide

It was Omicron strain "BA.5" that caused the spread of the "7th wave" that raged in Japan this summer.

The "BA.5" is still the most common in the world, but the proportion is gradually decreasing.

Especially in the United States, according to the CDC = Center for Disease Control, "BA.5" was 86.5% in the week until August 20, but it was 49.6% in the week until October 29, less than half. I was.

In place of that, the numbers that are increasing in each country are ``BQ.1'', ``BQ.1.1'', and ``XBB'', all of which are one type of Omicron strain with additional mutations.

Atsuro Hamada, a specially appointed professor at Tokyo Medical University who is familiar with the situation of overseas infections, said, "It is not possible at this stage to predict which will become mainstream in the future, but the various mutant viruses that have appeared do not have the ability to bind to human cells. While it has not changed in the past, it seems that the ability to evade human immunity has become stronger. Even if a mutated virus is detected, we need to look at it calmly."

So what kind of mutant viruses are these viruses?

Many reports from the United States and the United Kingdom "BQ.1" strain

In the week leading up to October 29 in the United States, ``BQ.1'' was 14%, ``BQ.1.1'' was 13.1%, ``BA.4.6'' derived from ``BA.4'' was 9.6%, and ``BA. "BF.7" derived from "5" is 7.5%.

"BQ.1", which has gradually increased, has further mutations added to the Omicron strain "BA.5".

Mutations such as "K444T" have been added to the "spike protein" part, which is a foothold when the virus infects human cells.

In addition, "BQ.1.1" is "BQ.1.1" with a spike protein mutation called "R346T" added to this "BQ.1".

Neutralizing antibodies are less effective, and the possibility of "immune escape" to escape from immunity has been pointed out, and there have been many reports since August in the United States and the United Kingdom.

According to WHO, "BQ.1" and "BQ.1.1" have been reported from 65 countries as of early October.

According to the data of the British health authorities, the international website "GISAID", which registers the gene sequence of the virus, reported for the first time that "BQ.1" increased by 75% every week since September, and "BQ. 1.1” is increasing by more than 90% every week.

The WHO expert group believes that the proportion of infected people tends to increase compared to previous Omicron strains, and while it may have a higher ability to escape immunity, it actually has a higher risk of severe disease if infected. There is no data to show that it has increased or that immune escape has occurred.

In general, the greater the ability of the virus to evade immunity, the greater the risk of post-vaccination infection and reinfection, but further investigation is needed at this time.

According to the WHO, conventional vaccines and vaccines containing components corresponding to the Omicron strain may be less effective in preventing infection, but do not appear to have a significant impact on preventing severe disease.

Increased “XBB” in Singapore, India, etc.

"XBB", which is increasing in Singapore and India, is a mutant virus ("BJ.1") derived from "BA.2" and a mutant virus ("BM.1.1.1") derived from "BA.2.75". It is a type of virus called "recombinant" that combines.

According to WHO, 35 countries have reported the virus as of late October.

The new coronavirus is constantly changing as it spreads around the world, and when one person is infected with multiple types, genetic recombination occurs, and a type called a ``recombinant'' that has the characteristics of multiple viruses. A new mutated virus can be made.

"XBB" is also such a type of mutated virus, and mutations such as "R346T" and "N460K" are added to the spike protein part, making it difficult for neutralizing antibodies to work, and it is possible that it has the property of "immune escape" that escapes immunity. gender is pointed out.

According to Singapore's Ministry of Health, XBB accounted for 54% in the week ending October 9, up from 22% the week before and becoming mainstream.

Furthermore, in mid-October, re-infections accounted for 17% of the number of newly infected people, and there is a view that re-infections are increasing and that the high infectiousness of "XBB" is affecting it. increase.

However, while the number of hospitalized patients has increased as the number of infected people has increased, the number of severely ill patients has not increased as much as the number of infected people and hospitalized patients, and at present there is no evidence that the risk of becoming severe is increasing. is.

The WHO expert group has pointed out that "XBB" is highly infectious, but it cannot be said that it has the ability to escape immunity or the rate of severe disease compared to the previous Omicron strain.

In addition, reinfection is also limited to people who were infected with the new coronavirus before the Omicron strain, and there is no evidence that it escapes the immunity obtained by the Omicron strain so far.

On the other hand, regarding whether the vaccine is effective, a group at Peking University in China has published experimental results on the effect of neutralizing antibodies produced by the vaccine in a paper before being peer-reviewed by a third party.

After being vaccinated three times with a Chinese-made vaccine, it has the effect of neutralizing antibodies against a virus that reproduces the characteristics of "XBB" artificially created using the blood of a person infected with "BA.5". In an experiment, the neutralizing antibody value was 1/18 or less compared to BA.5, and 1/27 compared to BA.2. .

The effect was significantly reduced under other conditions.

In Singapore, where "XBB" is spreading, the number of infected people turned to decrease after peaking in mid-October.

Professor Hamada said, "In Singapore, the number of infected people has been on a downward trend, and the spread to neighboring countries has not occurred so much. 'XBB' has been detected in Japan, but it has remained in a small number, and there is no concern about the spread. I don't think it's as high as it was for a while," he said.

Omicron Strain Mutations Still Going On?

New mutant viruses of the Omicron strain continue to appear one after another.

Among them, WHO pointed out in the weekly report on October 26 that an interesting phenomenon was observed in the mutation of the Omicron strain.

Although the newly emerged mutant viruses appeared separately, they have common mutations.

This phenomenon is called "convergent evolution," in which organisms that were originally different evolved separately, but ended up with common characteristics.

For example, the red king crab, which is a member of the hermit crab family, has adapted to the environment and evolved to have the same characteristics as crabs, such as claws.

This is a classic example of convergent evolution.

In the case of the new coronavirus, although it has mutated separately from different strains, it is said that the common part is mutated in the newly emerged mutant viruses.

The WHO says common mutations occur in parts of the virus that are thought to be necessary for adaptation to humans.

And it is possible that more mutations will be added.

What the experts see

Professor Yuuki Furuse of Nagasaki University, who specializes in virology, said, "It is said that half of the world's population has been infected with the Omicron strain. The new coronavirus has already mutated enough, and I don't know if it will continue to adapt to humans or if it will continue to mutate."

In addition, Professor Hamada of Tokyo Medical University said, "Mutation is concentrated in a certain place. For the virus, it means that it can evade human immunity by mutating that part. From the perspective of humans, it is not so easy to bring the epidemic to an end, and like influenza, it is possible that the epidemic will continue to evade immunity year after year. However, just like the flu, it may be possible to cope with it by getting vaccinated regularly."

Will the mutated virus lead to the 8th wave in Japan?

According to the data shown by the Tokyo Metropolitan Government as of noon on October 27, the percentage of "BA.5" in October in Tokyo was 94.3%.

The overwhelmingly large number has not changed, but it was 98% in August and 98.5% in September, so it is on a downward trend.

After "BA.5", "BA.2.75" and "BF.7" were the most common, both of which were in the 1% range.

In addition, "XBB" was reported 1 case in September and 5 cases in October in Tokyo, and was also reported in Kagoshima prefecture.

"BQ.1.1" was also reported in Tochigi Prefecture and other places in November.

The National Institute of Infectious Diseases says that although there is no evidence that "XBB" or "BQ.1.1" lead to aggravation, there are studies that point out that they have the ability to escape immunity, so they plan to continue monitoring. is shown.

Currently, the average weekly number of infected people in Japan reached about 26,000 on October 11, and then gradually increased to about 50,000 as of November 3.

Professor Hamada said, "The reason the number of infected people is increasing now is that BA.5, which was the mainstream in the 7th wave, did not completely disappear, and various easing measures were introduced in October. It is thought that it is in a state of rekindling from the embers.In this case, it will be possible to suppress it by taking preventive measures such as wearing a mask.However, if the "BQ.1" system enters, " BA.5, it is easier to evade immunity, and even if you are infected or vaccinated, you are more likely to be re-infected, so there is a possibility that the number of infected people will increase in the winter. Since "BA.5", "BQ.1" and "XBB" are all Omicron strains, vaccination against Omicron strains can be expected to have a preventive effect. I think it will lead to reducing health damage this winter."