Solène Leroux 3:26 p.m., November 27, 2021

Concern is growing about the Omicron variant, recently discovered in South Africa.

The first cases were detected in Belgium on Friday.

What do we know about this new variant of Covid-19?

Guest of Raphaël Delvolvé this afternoon, the virologist Vincent Maréchal takes stock for Europe 1.


A new variant that is panicking the whole world.

Discovered in South Africa, the Omicron variant is classified as "of concern by the WHO".

Guest from Europe Midi this Saturday, the professor of virology at Sorbonne University Vincent Maréchal returned to what we know about this new mutation of the coronavirus.

"It is a variant detected very recently, the first samples date from November 9," he explains.

This mutation is of concern because "the surface protein, the Spike, which is responsible both for the contagiousness of the virus and for escaping the immune response, shows a very high number of modifications compared to the forms that we knew".

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A concern about the effectiveness of vaccines

And it is precisely these modifications that worry specialists, because they have a "capacity to be transmitted in a more important way and to escape at least partially from the immune system" according to the virologist.

What to doubt the effectiveness of current vaccines?

The co-founder of the Obépine network, the Epidemiological Observatory in Wastewater, believes that two questions will arise in the coming weeks.

"We must first identify the role of several of the central mutations in the immune response", that is, the body's ability to defend itself against infection.


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For this, laboratory work is necessary "to find out whether the antibodies produced after vaccination are capable of neutralizing the virus".

The other possibility is a field approach by looking for "a maximum of cases of people infected with these variants, to count the people who, unfortunately, were infected while they were vaccinated", explains the virologist.

"The combination of these two parameters will allow us to know whether this virus can escape the natural immune response and the post-vaccination immune response."

Possible contagion in people who are already infected

Omicron is the second South African variant.

And that is not a coincidence according to the specialist.

The presence of another epidemic, that of HIV, "favors the adaptation of the coronavirus in people who have a fragile immune system".

More than eight million South Africans "are affected by this infection" recalls Vincent Maréchal.

"We see viruses appear in infected people which have adapted, and which can escape the immune response."

And this is the whole problem for epidemiologists: "It is believed that this virus is capable of infecting people who have already been infected with viruses previously."