Orange with Media Services, published on Sunday, December 19, 2021 at 7:00 a.m.
LANDMARKS. A month after being identified, this new strain appears very contagious and seems to escape vaccines in part.
A big unknown remains: the severity of the infections.
1. Where does the Omicron variant come from?
This is a new version of SARS-CoV-2 (the coronavirus that causes Covid), which has been identified at the end of November in Botswana, then in South Africa. Its peculiarity is its high number of mutations compared to the initial strain of the virus, known as Wuhan, and the previous variants, such as the Delta, which has largely dominated global contaminations since the summer of 2021.
It is not clear exactly where and how Omicron appeared. A hypothesis seduced many scientists: the virus would have gradually mutated at low noise in the body of an immunocompromised person, a process that would have taken several months to produce a version markedly different from the initial strain.
2. Is it more contagious than the previous variants?
It is obviously very contagious. This was only a hypothesis when it first appeared, but it became a certainty in the first weeks of December, given the epidemic situation in several countries. Omicron is spreading “at a rate we have never seen with any other variant” and “is probably found in most countries,” the director-general of the World Health Organization (WHO) warned this week, Tedros Adhanom Ghebreyesus. It has so far been identified in nearly 80 countries.
South Africa and its neighbors recorded an outbreak of Covid cases with the arrival of Omicron, which also saw a meteoric rise in several European countries. This is the case of Denmark and the United Kingdom. More broadly, Omicron could be dominant in Europe by mid-January, according to European Commission President Ursula von der Leyen.
3. Will he definitely replace Delta?
This is a high probability, but scientists suggest other possibilities: that Omicron supplants for a time its predecessor but ends up leaving it again, or that the two variants coexist as is the case for certain strains of seasonal influenza virus.
4. Are vaccines effective?
This is one of the great challenges posed by Omicron, as current vaccines are already losing their effectiveness over time against Delta variant infections. Mutations in Omicron are such as to considerably reduce antibody immunity against the virus. Consequence, it may possibly re-infect people previously with the virus and infect a large number of vaccinated people. Several recent studies, carried out in the laboratory, support this last hypothesis. They show that the antibody level collapses against Omicron in people vaccinated with Pfizer / BioNTech, Moderna, and even more AstraZeneca or Sinovac.
Admittedly, a booster dose seems to clearly boost immunity by antibodies, as announced by Pfizer and BioNTech in particular, but we are very far from knowing to what extent this effect persists over time. However, this does not mean that vaccines lose all of their effectiveness. Because antibodies are only one part of the immune response, which also involves cells called T lymphocytes. More difficult to measure, this “cellular immunity” nonetheless plays a very important role, especially against the forms severe disease.
In fact, a study published this week in South Africa suggests that the Pfizer / BioNTech vaccine remains rather effective against the severe forms generated by Omicron, including after the first two doses.
5. Do the treatments cure this variant?
Omicron also seems to pose difficulties for synthetic antibody treatments, especially used in patients already hospitalized. On the other hand, we can hope that it does not resist the anti-Covid pills recently announced by the Merck and Pfizer laboratories. However, this is a hypothesis, linked to the functioning of these drugs, which still needs to be supported by the facts.
6. Is it less dangerous?
It is now the great unknown. Clinical data from the past few weeks clearly suggests that Omicron is no more dangerous than its predecessors, including Delta. It is “almost certain”, according to the eminent American scientist Anthony Fauci, who even believes that it could be less dangerous.
But should we bet on this eventuality? It is a risky bet. Already, Omicron is certainly not painless, as shown by a first death recorded earlier this week in the United Kingdom. Above all, scientists warn against an optical effect. If Omicron is less dangerous but much more contagious, the consequences will indeed remain serious at the collective level.
“We are concerned that people consider Omicron to be benign,” worries the boss of the WHO. “Although Omicron causes less severe symptoms, the number of cases could once again overwhelm health systems who are not prepared. ”