Threatens to change the face of the Covid-19 epidemic. Almost a month after its detection, the Omicron variant appears more contagious and appears to partially evade vaccines. The great unknown remains the severity of the infections.
Who is Omicron?
It is the result of a mutation in SARS-CoV-2 and was detected in late November in Botswana and then in South Africa.
Its peculiarity is the increased number of mutations in relation to the original strain of the virus that appeared in China and in relation to previous variants, such as the Delta, which has dominated the world since the summer of 2021.
It is not known where and how Omicron appeared. One hypothesis prevails among scientists: the virus mutated slowly and silently in the body of an immunocompromised individual, a process that took many months to arrive at a completely different version of the original strain.
What changes?
It is obviously very contagious. This was a case in point, which became a certainty in the first weeks of December based on the evolution of the epidemiological situation in many countries.
“Micron is spreading” at a rate we have not seen in any other variant “and” is likely to be present in most countries, “warned World Health Organization Director-General Andrew Gembreses.
South Africa and neighboring countries experienced a resurgence of Covid cases with the arrival of Omicron, which also increased in many European countries, with the United Kingdom and Denmark leading the way.
More broadly, Omicron is likely to become the dominant variant in Europe by mid-January, according to Commission President Ursula von der Leyen.
Will it permanently replace Delta? Chances are, scientists point to other possibilities: Omicron will replace Delta’s predecessor, but eventually leave the post again, or the two variants will coexist, as is the case with some strains of seasonal flu.
And the vaccines?
It’s one of Omicron’s biggest challenges, as current vaccines are at a point where their effectiveness is declining over time.
Omicron mutations can significantly reduce immunity to the virus through neutralizing antibodies. Consequence: Omicron can potentially re-infect infected people and infect a significant number of those vaccinated.
Many recent studies in the laboratory support this hypothesis. They show that the levels of antibodies against Omicron are reduced in those vaccinated with Pfizer / BioNTech, Moderna and also with AstraZeneca or Sinovac.
Of course, a booster dose seems to greatly restore antibody immunity, as announced by Pfizer and BioNTech. But it is not known if this immunity lasts over time.
However, this does not mean that vaccines lose all their effectiveness. Because antibodies are only one part of the immune response, which also includes T cells. This cellular immunity is more difficult to measure, but plays a very important role, especially in severe forms of the disease.
Thus, according to a study published this week in South Africa, the Pfizer / BioNTech vaccine remains highly effective against severe disease, even after two-dose vaccination.
Omicron also appears to cause problems in the treatment of synthetic antibodies, which are mainly used in hospitalized patients.
On the contrary, it is hoped that Omicron will not resist the anti-Covid tablets recently announced by Merck and Pfizer. However, this is a case that needs to be proven in practice.
Less dangerous?
This is the big stranger. Clinical data from recent weeks lead to the conclusion that Omicron is no more dangerous than its predecessors, especially Delta.
It is now “almost certain,” leading infectious disease specialist Anthony Fauci said in early December, adding that it was likely to be less dangerous.
But should we bet on that? It’s a risky bet. Scientists warn of optical error. If Omicron is less dangerous and more contagious, the consequences will remain serious on a collective level.
“We are concerned about the fact that people consider Omicron mild. “Even if Omicron causes less severe symptoms, the number of cases is capable of causing a flood of health systems that are not prepared for this development,” warned the WHO director general.
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