Covid-19: Omicron, a variant that will change the face of the pandemic?;

It threatens to change the face of the Covid-19 epidemic. Almost a month after its detection, the Omicron variant appears to be more contagious and seems to partially evade vaccines. The big unknown remains the severity of infections.

What is Omicron?;

It is the result of a mutation of SARS-CoV-2 and was detected in late November in Botswana and then in South Africa.

Its peculiarity is the increased number of mutations compared to the original strain of the virus that appeared in China and compared to previous variants, such as Delta, which has been dominant worldwide since the summer of 2021.

It is not known where and how Omicron appeared. One hypothesis prevails among scientists: the virus mutated slowly and quietly in the body of an immunocompromised individual, a process that took many months to result in a completely different version of the original strain.

What is changing?;

It is evident that it is highly contagious. This was a hypothesis when it first appeared, which became a certainty in the first weeks of December based on the development of the epidemiological situation in many countries.

Omicron is spreading «at a rate we have not seen in any other variant» and «is likely present in most countries,» warned World Health Organization Director-General Tedros Adhanom Ghebreyesus.

South Africa and its neighboring countries have seen a resurgence of Covid cases with the arrival of Omicron, which has also seen an increase in many European countries, notably the United Kingdom and Denmark.

More broadly, Omicron is likely to become the dominant variant in Europe by mid-January, according to statements by European Commission President Ursula von der Leyen.

Will it permanently replace Delta? The possibility is high, but scientists also mention other possibilities: Omicron will replace its predecessor Delta, but will eventually give way to it again, or the two variants will coexist, as is the case with certain strains of seasonal flu.

What about vaccines?;

This is one of the major challenges facing Omicron, at a time when current vaccines are reaching a point where their effectiveness is waning over time.

Omicron mutations can significantly reduce immunity against the virus through neutralizing antibodies. Consequence: Omicron may potentially re-infect individuals who have already been infected and affect a significant number of vaccinated individuals.

Many recent laboratory studies support this hypothesis. They show that antibody levels against Omicron are reduced in people vaccinated with Pfizer/BioNTech, Moderna, and also AstraZeneca or Sinovac.

Of course, administering a booster dose appears to largely restore immunity through antibodies, as announced by Pfizer and BioNTech. But it is not known whether this immunity lasts over time.

However, this does not mean that vaccines lose all their effectiveness. This is because antibodies are only one part of the immune response, which also includes T lymphocytes. This cellular immunity is more difficult to measure, but it plays a very important role, especially in severe forms of the disease.

According to a study published this week in South Africa, the Pfizer/BioNTech vaccine remains largely effective against severe disease, even after two doses.

Omicron also appears to cause problems with synthetic antibody treatments, which are mainly used in hospitalized patients.

On the contrary, it is hoped that Omicron is not resistant to the Covid tablets recently announced by Merck and Pfizer. However, this is a hypothesis that needs to be proven in practice.

Less dangerous?;

This is the big unknown. Clinical data from recent weeks suggest that Omicron is no more dangerous than its predecessors, particularly Delta.

It is now «almost certain,» leading infectious disease expert Anthony Fauci said in early December, adding that it is likely to be less dangerous.

But should we bet on this possibility? It's a risky gamble. Scientists warn of an optical illusion. If Omicron is less dangerous and more contagious, the consequences will remain serious on a collective level.

«We are concerned that people consider Omicron to be mild. Even if Omicron causes less severe symptoms, the number of cases is capable of overwhelming health systems that are not prepared for this development,» warned the WHO Director-General.