Covid-19: two weeks after its appearance, what do we know about the Omicron variant?

While several hundred cases of the Omicron variant have been detected in Europe in recent weeks, its profile is becoming clearer. Contagiousness, virulence, resistance to vaccines … Le Figaro make the point.

His sudden appearance caused a wave of panic. On November 24, the B.1.1.529 variant was reported for the first time to the World Health Organization (WHO) in South Africa. But the first known confirmed case of infection dates back to November 9. “He probably shoots in South Africa […] for longer than we thought, since early October“, Also suggested at the beginning of December the president of the Scientific Council Jean-François Delfraissy. Quickly cataloged as “worrying variantBy the WHO, it was baptized Omicron, like the letter of the Greek alphabet. Since then, several hundred cases of this mutation have been detected in Europe, and speculation is rife: is it transmitted more easily? Is it more dangerous? Worse, is it resistant to vaccines? Le Figaro takes stock of what we know, and what we do not yet know about it.

  • Greater transmissibility …

We can see that the Omicron variant has a potential for very rapid spread.“, In particular because of a number”extremely high»Of mutations, had alerted, as soon as the variant was discovered, the virologist Tulio de Oliveira, a member of the scientific team who had discovered the Beta variant. While it will probably take a few more weeks to refine this statement, specialists agree that the Omicron variant is more transmissible than its predecessor Delta. Omicron is “clearly highly transmissible“, Thus affirmed Wednesday Anthony Fauci, adviser of the White House.

Data from South Africa, where the variant is now the majority, seem to prove it. As of December 8, the country had more than 13,000 new cases of Covid-19 daily, on average over seven days, against less than 1,000 two weeks previously, when Omicron emerged.

SEE ALSO – Omicron variant: “The cases are mostly light”, reassures the EMA

  • … But less virulence?

If the Omicron variant is gradually spreading throughout the planet, no death has, for the time being, been associated with it. Here again, caution is called for, since the available data are limited. But the WHO has recently been reassuring, explaining that “there is evidence to suggest that Omicron causes less severe symptoms than Delta, currently the most common variant“. “The general behavior we are seeing so far shows no increase in severity. In fact, some places in southern Africa report milder symptoms“, Said Dr Michael Ryan, WHO emergency manager. Angelique Coetzee, president of the South African Medical Association, also spoke at the end of November of “mild symptoms“, like a “extreme fatigue“, Muscle aches, a dry cough or”a itchy throat“.

Hospitalization data are also rather reassuring in South Africa, but it should be remembered that the population is rather young, therefore less at risk of serious forms. In Europe, all documented cases are “either symptom-free or mild“, For its part indicated the European Center for Disease Prevention and Control (ECDC). In any case, that would open the door to an optimistic conjecture. “If the Omicron is highly transmissible, but not nasty, it would give group immunity and help alleviate the mild seasonal virus SARS-CoV-2, which would signal the end of the crisis.“, Noted the French virologist Bruno Canard to AFP. But he clarified that such a scenario would be a “stroke of luck“.

  • Are children more affected?

As Le Figaro explained on December 3, according to hospital data from Tschwane, which is the epicenter of the restart of the epidemic in South Africa, the under-five are the second most affected age group, after over 60 years. For hospital admissions, “we are registering a fairly strong increase in all age groups, and particularly among those under fiveSaid Wassila Jassat, public health specialist at the South African National Institute for Contagious Diseases (NICD). In fact, more than a hundred young children had been admitted to hospital on December 3. The number of positive cases is also increasing among 10-14 year olds in this country with a particularly young demography.

SEE ALSO – Omicron: “For the moment, our enemy is the Delta variant”, according to Professor Arnaud Fontanet

For now, South African authorities do not know if this is attributable to the Omicron variant itself, or if many parents have gone to the emergency room, concerned by recent government announcements. According to Wassila Jassat, this contamination of the youngest could be explained by the fact that those under 12 are not eligible for the vaccine in South Africa and that it is therefore possible that, if the children are not vaccinated and the parents either, the whole family is infected.

  • Greater resistance to vaccines …

WHO announced on Wednesday that “preliminary data from South Africa suggest a risk of reinfection “of people cured of the disease or vaccinated”higher with Omicron“. In fact, initial studies, which have not yet been independently reread and carried out in vitro, show this week that the vaccinated people seem to generate much less effective antibodies against Omicron than against the previous variants. “Vaccine immunity is not totally bypassed, which is good news. But the mutations changed the structure of the virus, making the antibodies much less effective at recognizing it.», Recently confided to Figaro Mylène Ogliastro, virologist and research director at INRAE ​​in Montpellier. An international team, led by Alex Sigal, virologist at the African Institute for Medical Research in Durban (South Africa), also mentions a “significant loss of efficiency“.

However, it is difficult to draw precise conclusions, because the level of antibodies only partially prejudges the real effectiveness of the vaccines. Antibodies are only one part of the immune response, which also involves cells called T lymphocytes. More difficult to measure, this “cellular immunity»Does not play less a very important role, in particular against the serious forms of the disease.

  • … But a third saving dose?

On Wednesday, Pfizer and BioNTech laboratories announced that the immune response linked to their vaccine was “significantly reduced“Versus Omicron for patients who received two doses, but the third dose offered”a high level of protection“. Their studies have indeed measured in the laboratory the degree of antibodies produced against the new variant in vaccinated people.

SEE ALSO – Covid-19 vaccine: up to how many doses will we go?

Reducing the waiting time between second and third doses could be “a good way to do it“To increase the effectiveness of the vaccine, said BioNTech CEO Ugur Sahin, citing a delay of”three monthsInstead of five to six months. The two companies are, however, working on a new version of their vaccine, perfectly suited to the new variant, which should be “available by March”.


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