Omicron: BA.2, the sub-variant that raises new questions – Le Monde

Appeared a few weeks ago, a sub-variant of Omicron is now closely followed by epidemiologists. If BA.2 – the name of this sub-variant – seems close to the initial version, scientists want to know more about its characteristics and its possible consequences on the Covid-19 pandemic.

The name Omicron is actually a ” generic term “ which designates without distinction several very close virus lineages, explains the World Health Organization (WHO), Friday January 21, in its weekly update. Among these brother lineages supervised under the name of Omicron, it is the one designated by the name BA.1 which is almost hegemonic. But certain data attract attention: BA.2, another of these lineages, would have become the majority in India or Denmark, where the number of daily cases has started to rise again.

“What surprised us was how quickly this sub-variant, which circulated a lot in Asia, settled in Denmark”epidemiologist Antoine Flahault told Agence France-Presse (AFP). “The country was expecting a peak in contamination in mid-January; it did not occur and may be due to this subvariant, which appears highly transmissible but no more virulent” than the original variant, he continues.

Scientists cautious but not alarmist

For the moment, the health authorities are waiting to learn more.

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

To date, the BA.2 sub-variant has been detected in France, “but at very low levels”. In Denmark, on the other hand, it is gradually replacing the BA.1, the Omicron variant “classic”noted the French public health agency. “The Danish authorities have no explanation for this phenomenon but it is being closely monitored”, she added. France on its side “closely follows the data that will be produced by Denmark”.

Cautious, scientists do not seem alarmist. For Antoine Flahault, it is still too early to worry, but the “vigilance” is appropriate. “We have the impression for the moment that it is of a severity comparable to Omicron but many questions are still on the table”he adds, inviting “put in place screening techniques to properly detect” BA.2 and “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”, 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 Omicron version, he does not expect a change equivalent to that which occurred when the latter variant supplanted Delta. “I don’t think BA.2 is going to have a substantial impact on the current wave of the pandemic”he observed.

The Minister of Health Olivier Véran also estimated Thursday that BA.2 does not “don’t change the situation” at this stage, while avoiding a final judgement. “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”added the minister.