Health

Detecting a sub-variant of Omicron


The strain BA.2 is a subline of Omicron that is rapidly spreading and gaining popularity in countries such as India, Denmark and Sweden.

BA.2 first appeared in India and South Africa at the end of December 2021. It is considered a sublinear, emerging from a mutation of Omicron. Omicron himself was also born from a mutation of the Delta strain.

On January 20, French Health Minister Olivier Véran first mentioned this mutation, and said that health authorities are analyzing and closely monitoring BA.2.

This strain has more than 20 mutations, about half of which are in the spike protein, the part the virus uses to attach to human cells, the key to helping pathogens enter the body.

The World Health Organization (WHO) has classified Omicron as a worrisome mutation. At this stage, the organ does not distinguish between Omicron and its BA.2 substream.

Scientists are studying the BA.2 variant, but there are still no data to determine vaccine resistance or its severity. The initial reports were rather cautious.

Citing preliminary research from India and Denmark, Tom Peacock, a virologist at Imperial College London, said the symptom severity of BA.2 was not much different from that of Omicron. Experts may get more solid data in the coming weeks.

“Personally, I don’t think BA.2 has had a significant impact on the raging Omicron wave. Some countries are near or even past the peak of the epidemic. I would be quite surprised if BA.2 caused a wave. the second wave at this point. Even with a high degree of transmission, it won’t have as much impact as Delta or Omicron. It will probably spread more slowly and be more subtle,” added Mr. Peacock.

People wear masks to prevent Covid-19 infection in Paris, France, December 2021. Photo: Reuters

According to epidemiologist Antoine Flahault, director of the Institute of Global Health of the University of Geneva, countries should pay attention to understanding the ability of antibodies to BA.2. They need to see if people infected with Omicron are re-infected with this variant.

BA.2 is difficult to track and poses certain challenges for scientists. According to Florence Débarre, a biologist at the Institute of Ecology and Environmental Sciences in Paris, PCR tests and procedures are now very diverse. They vary from country to country, manufacturer and even laboratory to laboratory. This makes it very difficult to identify people infected with the BA.2 variant.

“In the UK, the tests don’t allow us to distinguish between BA.2 and Delta,” he said.

Scientists can sequence genes to find people infected with the BA.2 variant. This is a more accurate but less popular tool. In France, for example, only a few laboratories are qualified to do this. Sequencing also takes a long time, making it unsuitable for monitoring a rapidly spreading strain.

BA.2 has been detected in at least 43 countries, on all continents. It became popular in India, Denmark and Sweden. In Denmark, the number of daily nCoV infections has started to increase again, just when the country thought the epidemic had peaked.

“The Danish authorities do not have an explanation for this phenomenon, but everything is being closely monitored. It is possible that BA.2 is more contagious,” said the French public health agency, which is monitoring the new strain. in Denmark, said.

Previously, on January 9, scientists from the University of Cyprus discovered a new strain, tentatively named Deltacron, carrying genetic signatures of the Omicron and Delta strains.

Leondios Kostrikis, a professor of biological sciences at the University of Cyprus, said he and his colleagues had detected 25 cases of Deltacron infection, which carries the Delta genome but has Omicron-like mutations. The viral gene sequences of 25 cases have been submitted to GISAID, an international database specializing in tracking changes in nCoV.

Thuc Linh (Follow France24)

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