[Chicago, 30th Reuters]–The rapid spread of the new coronavirus has already peaked out in some countries, but it is still far from converging. And almost all of the infections in the world today are dominated by the highly infectious Omicron strains. However, what scientists are now wary of is that “BA.2”, which is one of the derivatives of this Omicron conventional strain “BA.1”, is from “BA.1” in parts of Europe and Asia. It is a situation that is gaining momentum in the form of replacement. The following is a summary of what has been known about “BA.2”.
◎ “Stealth Omicron”
Based on genome analysis data registered in the influenza virus gene database (GISAID), a global scientific initiative, as of 25th of this month, 98.8% of the world’s new coronavirus infections are “BA.1.” However, according to the World Health Organization (WHO), reports of “BA.2” infections have been increasing recently.
In addition to “BA.1” and “BA.2”, WHO also lists two types of Omicron derivative strains “BA.1.1.259” and “BA.3”. Although they are genetically similar, their functions may differ depending on the characteristics of each subtly mutated.
Trevor Bedford, who is conducting virus research using computational science at the Fred Hutchinson Cancer Research Center, said on the 28th, based on GISAID information and the database “Hour World in Data” operated by Oxford University. , “BA.2” accounts for about 82% of infections in Denmark, 9% in the UK and 8% in the US, he posted on Twitter.
“BA.1” was somewhat easier to detect than previous mutant strains. “BA.1” is because one of the three “target genes” used in general PCR tests is deleted, and when a virus with this characteristic is detected, “BA.1” is automatically used. It has been presumed to be.
On the other hand, “BA.2”, sometimes called “stealth omicron”, does not have a deletion of the target gene like “BA.1”. So scientists are watching the trend in the same way as previous mutants, including Delta strains, by tracking the number of genomes registered in public databases such as GISAID.
Experts say that “BA.2” can be detected with a home-use test kit like other mutants, but it is not known which mutant causes the symptoms.
◎ Has the infectivity increased?
It is beginning to be reported that “BA.2” has a higher infectivity than “BA.1”, which is already very strong. So far, however, there is no evidence that the vaccine’s ability to evade its protective function has increased.
Based on preliminary data, Danish health officials estimate that while the infectivity of “BA.2” is 1.5 times that of “BA.1”, it is unlikely to increase the risk of aggravation. ..
According to the results of a contact follow-up survey conducted by the British Health and Security Agency in England from December 27th last year to 11th this month, the domestic infection rate of “BA.2” is 13.4%, which is the same as that of other Omicron strains. It was also found to be higher than 10.3%. According to the agency’s 28th report, there seems to be no difference in the vaccine effect.
Egon Ozel, an infectious disease expert at the Feinberg School of Medicine at Northwestern University, raised the serious question of whether “BA.1” infected people would be infected with “BA.2”. Talk to come.
Mr. Ozel points out that there is a growing interest in this issue, with reports of an increase in “BA.2” infections in some areas where “BA.1” infections were severe in Denmark. .. If a “BA.1” infected person cannot prevent the “BA.2” infection, he is concerned that the wave of infection may have two peaks, but “it is time to figure out what will happen.” It’s too early. “
Still, he said, it’s good news that previous vaccinations and boosters continue to reduce the risk of hospitalization and death.
