BA.2: What do we know about Omicron stealth sub-lineage variant already spreading in France?

Published by Manon de Sortiraparis · Published on January 22th, 2022 at 11:25 a.m.
A new Omicron sub-lineage variant, called BA.2, has broken out in the world over the past few days. About twenty cases have been reported in France already.

As the Omicron variant is now prevailing in France and the world, a new variant broke out: BA.2. Omicron sub-lineage (BA.1) variant, or in other words, a mutation of the historic variant, BA.2 is found in already half of Covid cases sequenced in Denmark, but widely in Israel, where it has been first reported on January 13, 2022.

Nicknamed “stealth Omicron”, because it is harder to find than Omicron, BA.2 has since then spread to the United Kingdom, Belgium, Canada, Philippines, Singapore, South Africa, Australia, as well as France, where about twenty cases have been reported, according to Le Parisien daily.

Shall we expect a rise in contaminations as the new Covid case toll is breaking records on a daily basis? Suspected to be more contagious than Omicron, BA.2 is likely to be at the origin of the epidemic resurgence in Denmark. But for now, it is impossible to know if the same situation is likely to occur in France.

If one drives at 55 and the other at 56 mph, it takes a lot of time for the other one to get ahead”, Institut Pasteur scientist Etienne Simon-Lorière told Le Parisien, excluding in the event of “mega clusters” likely to reshuffle cards. “The key is to find out if this sub-lineage variant can reach people who have just been contaminated. It is unlikely but we need to study it thoroughly. As long as this question is unanswered, forecasting is a very risky exercise”, Geneva Global Health Institute manager Antoine Flahault told LCI.

According to Pr. Flahault, data are still lacking to be able to draw conclusions about this sub-lineage variant. “We don’t know where it comes from, its virulence, its capacity of escaping immunity, including if provided by Omicron”, he says. He goes on: “BA.2 has been spotted by several teams in the world. We’ll quickly have to know if it escapes immunity provided by the vaccine and prior infections, and find out more about its virulence. Let’s have a closer look at the situation in Denmark, it will be enlightening”.

What about lethality of this sub-lineage variant? Could it be more dangerous than the Omicron variant? “It’s very unlikely. Both viruses are close enough in terms of Spike protein to think they behave more or less the same way”, Etienne Simon-Lorière thinks.

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