Omicron BA.2 subvariant: is it more contagious or more dangerous than other viruses?

While most European countries are announcing the easing of health restrictions against Covid-19, the specter of a new wave of contamination is raising concern among the scientific community.

A sub-variant of Omicron, also detected in France, is now being closely monitored by the health authorities. baptized BA.2, he is already majority in Denmark and India, and has several mutations that could once again change the characteristics of the SARS-CoV-2 virus

Should we worry about the emergence of the BA.2 sub-variant which may soon take the place of its “big brother” Omicron?

It is a derivative of the Omicron variant

The name Omicron is in fact a “generic term” which designates without distinction several lineages of very close viruses, as explained by the World Health Organization (WHO).

Among these variant sublineages monitored under the name Omicron, it is the one designated by the appellation BA.1 which is almost hegemonic and causes record contamination in France.

According to numerous studies, the Omicron variant is much more contagious than Delta but has characteristics that make it less virulent.

The strong spread of the Omicron variant significantly increases the likelihood that new subvariants will appear. Mutations are actually the result of “errors” during the virus replication process. So according to this principle, the greater the contamination, the more likely the appearance of new mutations. The Delta variant had also given rise to sub-variants such as “Delta plus”.

Is it more contagious?

Certain data attract attention: BA.2, would thus have become the majority in India or Denmark, where the number of daily cases has started to rise again for a few days.

“What surprised us was how quickly this sub-variant, which circulated a lot in Asia, settled in Denmark”, says epidemiologist Antoine Flahault.

“The country was expecting a peak in contaminations in mid-January; it did not occur and perhaps it is due to this sub-variant, which seems very transmissible, but not more virulent” than the original variant, he continues.

In Denmark, BA.2 is gradually being replace the “classic” Omicron variant, and the Danish authorities have no explanation for this phenomenon at the moment.

But according to the first available elements, it is very likely that this sub-variant is more contagious.

Is it more dangerous than the other variants?

This is perhaps the most important question at the moment. With the Omicron variant, the European Medicines Agency (EMA) believes that we will “towards an endemization of the virus”, but this will only be possible if the dangerousness of the virus does not increase.

A new variant, more resistant to vaccines and more dangerous, would end the hope of a near end to the pandemic.

“What interests us is whether (this subvariant) has different characteristics (from BA.1) in terms of contagiousness, immune escape or severity”, noted the French public health agency on Friday.

However, although cautious, scientists do not seem alarmist. For epidemiologist Antoine Flahault, it is still too early to worry, but the “vigilance” is appropriate.

“For the moment, we have the impression that he is comparable in severity to Omicron but many questions are still on the table”, adds the director of the Institute of Global Health at the University of Geneva.

He invites to “put in place screening techniques to properly detect“BA.2 et “see quickly what its properties are”.

“Very early observations in India and Denmark suggest that there is no major difference in severity compared to BA.1”, also tweeted Tom Peacock, a virologist at Imperial College London.

According to him, the mutations observed should not call into question the effectiveness of vaccines either.

“Even with slightly higher transmissibility” than the classic version of Omicron, he absolutely does not expect a change equivalent to that which occurred when this last variant supplanted Delta.

“I personally don’t think BA.2 is going to have a substantial impact on the current wave of the pandemic,” he noted.

Oliver Véran: BA.2 “does not change the game”

The French Minister of Health, Olivier Véran, was rather cautious on Thursday. “There are variations fairly regularly”, he recalled during a press conference with Prime Minister Jean Castex. “For what we know so far, it more or less matches the characteristics we know of Omicron.”

He … not “don’t change the situation” at this stage, added the minister. Like the Delta variant before it, the Omicron variant, by replicating, has generated “little brothers”, sub-lineages which contain one or two mutations compared to the original genome.

The World Health Organization (WHO), which has classified Omicron as a “variant of concern”, does not at this stage make a distinction with the BA.2 subvariant.

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