Among the Omicron strains of the new coronavirus, a type of virus called "XE", which is a combination of multiple types, has been reported in the United Kingdom and other countries.

The susceptibility to the spread of the infection is not clear, and although experts need to pay close attention to it, the basic measures remain unchanged.

The new coronavirus is constantly changing as it spreads around the world, and when one person infects multiple types, genetic recombination occurs, creating a new mutant virus with the characteristics of multiple viruses. I have.



Of these, the virus called "XE" is a type called "BA.1" (BA.1) that spread in the "6th wave" of the Omicron strain, and "BA.2" (BA.2), which is said to be more infectious. It is a type that combines two).



Most of the parts that are on the surface of the virus and contain spike proteins that serve as a foothold for infecting human cells are "BA.2", and the other parts are "BA.1".



WHO = World Health Organization monitors "XE" as a type of Omicron strain, and according to data from the UK health authorities, it was first reported in the UK on January 19, 2022, until March 22. 763 cases have been reported, and small clusters have also been reported, but as of late March, they accounted for less than 1% of all viruses detected.

In addition, when analysis using a mathematical model was performed based on the initial data up to March 15, it was estimated that the speed of infection spread was 9.8% faster than "BA.2", but WHO said. Further confirmation is needed.

"XE" has not been found in Japan yet, so Takaji Wakita, chairman of the expert meeting of the Ministry of Health, Labor and Welfare, said at a press conference on the 6th, "There are reports that the XE strain has been found in Japan's quarantine so far. No, it has not been found in Japan. It is not widespread in the United Kingdom, and the relationship between severity is not well understood. We need to continue. "



There are other viruses that combine multiple viruses, of which "XD" and "XF" (XD / XF) are the Delta strain that spread in the "Fifth Wave" last summer and Omicron. Among the stocks, it is a type that combines the type called "BA.1".



"XD" has a spiked protein part of "BA.1" and most of the rest is a Delta strain. According to the data of the British health authorities, it was first detected on December 13, 2021. As of March 22, 2022, 40 cases were reported in France, 8 cases in Denmark, and 1 case in Belgium.



WHO positions "XD" as a mutant strain under the supervision of "VUM" (VUM), whose degree of influence on infectivity, severity of infection, and vaccine effect is unknown. The spread of the infection is limited.



In addition, most of "XF" including spike protein is "BA.1", and some are delta strains.



Health officials in the United Kingdom have found 39 cases in the United Kingdom since January 7, 2022, but have not reported since February 14, and the spread of the infection has not been seen.



According to WHO, the risk of new mutant viruses being created due to the combination of multiple viruses is still high, and it is still essential to analyze the genes of the virus and share the data.

Professor Koji Wada of the International University of Health and Welfare, who is a member of the expert meeting of the Ministry of Health, Labor and Welfare, said, "There have been some combinations of alpha and delta strains, and even Omicron strains have" BA.1 "and" BA. " Since there are two types of ".2", it was thought that it is possible that a combination of infections would occur at the same time. It is not a virus with a completely unexpected mutation. However, it seems unlikely that the major policy for countermeasures will change. Nowadays, "BA.2" is becoming the mainstream, but even with XE stocks, the basic daily countermeasures do not change, and this is the third time. The policy of wanting to continue vaccination remains unchanged. "

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