Contagiousness, resistance to vaccines… What do we know about the Omicron variant?

• Discovered in South Africa in November, the Omicron variant worries the international community.

• Great Britain fears a "tidal wave" of contamination due to this variant and is accelerating the vaccine booster campaign.

• Scientists are starting to publish data on this variant.

  Contagiousness, lethality, resistance to vaccines…

  20 Minutes

  recaps what we know for the moment.

"We are facing two challenges in parallel: administering the 3rd dose as quickly as possible to counter the fifth wave of Covid-19 and organize ourselves to deal with the Omicron variant in the short term if we are to believe the models", summed up Thursday last Odile Launay, the coordinator of the Cochin-Pasteur clinical research center for vaccinology.

The rich news of recent days confirms that Omicron is needed and worries ... If the data is still fragmented on this new variant, several studies are shedding light on scientists.

takes stock.

Is he more contagious than Delta?

It seems so.

On Sunday, the World Health Organization drew up a first profile of this variant: Omicron seems to be spreading more than the Delta variant.

This faster spread is seen not only in South Africa, but also in the United Kingdom.

With more than 58,000 new Covid-19 contaminations recorded on Friday, unheard of since January, Boris Johnson speaks of a "tidal wave".

Already 30% of the cases reported in London are linked to the Omicron variant, identified in the country only a fortnight ago.

The British Health Safety Agency (UKHSA) said Omicron is expected to become the dominant variant in the UK by mid-December and the number of infections is likely to exceed one million.

Is France heading straight for this scenario? According to the opinion of the Scientific Council published on Monday, this variant could "circulate in Europe more quickly than initially expected, by gradually replacing the Delta variant in the first weeks of 2022.". For the moment, according to Public Health France, three cases had been identified on December 1, and 133 on December 12.

But is France sequencing enough to closely follow the emergence of this variant? “Of course, the British are sequencing more than us, but they also have more relations with South Africa, that plays on the number of contaminations, nuance Yazdan Yazdanpanah, head of the infectious diseases department of the Bichat hospital (AP- HP) and member of the Scientific Council. We are not in a situation where we cannot see because we do not sequence enough. In Norway and Denmark, [where the variant also prevails], there have been clusters. If we had huge clusters, we would see them. "

Asked Tuesday morning on France Bleu, Jean Castex clarified: “Even if the circulation of Omicron today in France remains weak, our duty is to anticipate on the basis of what we know.

The British say it is much more contagious than Delta, which itself was more contagious than its predecessors.

"

Is it more lethal?

In South Africa, where this variant has emerged, few serious cases are listed, even as the tests and the positivity rate (28.9%) reach records.

Only deaths have not seen a significant increase so far, with most patients showing mild symptoms at this stage.

Still, the population of this country is much younger than ours… Anthony Faucci, the American “Mr. Covid”, suggested on December 7 that this variant could be less dangerous than Delta.

Yet on Monday, the first death with Omicron, in Great Britain, threw a chill.

For the moment, France has no deaths linked to this variant.

Last Thursday, Vincent Calvez, head of the virology department at Pitié-Salpêtrière (AP-HP), wanted to be optimistic: “there are many hospitals which are sequencing all their patients.

For the moment, we do not have Omicron in hospitalized patients, therefore the most serious.

"

Does this mean that we could have a 6th wave of Omicron that would not weigh on the health system?

In its opinion published Monday, the Scientific Council is very cautious: "if we can expect that vaccination protects against serious forms, the very large circulation of the virus, including in the immune population, will end up affecting people. at risk of severe forms: unvaccinated subjects, subjects at risk who have not achieved their booster dose, and subjects with immune deficiencies in whom vaccination is not effective.

This will result in an increase in hospitalizations which will be added to those linked to the Delta wave.

"

Are vaccines still effective against Omicron?

This is THE question today. Several studies in recent days provide valuable, but preliminary information. A first comes from South Africa and suggests a significant drop in the neutralizing power of vaccines, but it concerns only twelve patients. This Tuesday, a second study, also carried out in South Africa and much larger, qualifies this worrying result. This work, developed by the country's leading private health insurance company, Discovery, with scientists from the South African Medical Research Council (SAMRC), is based on 78,000 PCR tests carried out between November 15 and December 7.

"The double dose of the Pfizer vaccine shows 70% effectiveness in reducing hospital admissions," said Discovery president Ryan Noach. The vaccine was previously 93% effective against severe cases. In general, "the effectiveness of the vaccine is significantly reduced with a high number of brief contaminations in vaccinated people," he continued. The study shows an efficacy of only 33% against the risk of contamination, with a high number of re-infections, against 80% against the previous dominant variant Delta.

So, does the third dose protect more?

Last Wednesday, Pfizer presented a study revealing that in the face of Omicron, two doses were no longer sufficient to protect against severe forms.

"On the other hand, what is a little reassuring, even if these results must be taken with caution, is that after a third dose, there remains a neutralizing power against Omicron", nuance Odile Launay.

Who concludes: “this variant will impact protection.

This requires speeding up the 3rd dose.

"

Health

Coronavirus: France risks rapid growth of the Omicron variant

Health

Coronavirus: Omicron variant resists Pfizer vaccine but does not escape it completely, study finds

• Omicron variant

• epidemic

• Covid 19

• Anti-covid vaccine

• Coronavirus

• Health

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