Ómicron, a very contagious version of COVID-19

Ómicron is a variant of COVID-19 detected about a month ago and due to its high degree of transmission, it can once again change the course of the pandemic, especially due to its impact on vaccination.

What is omicron?

Ómicron is a new version of SARS-CoV-2 (the coronavirus originating from the pandemic), identified at the end of November in Botswana, and later in South Africa.

Its particularity is the large number of mutations with respect to the original variant that was detected in the Chinese city of Wuhan, and of later versions, such as the delta, which until now largely dominates the transmission of the pandemic.

It is not known how omicron appeared. One hypothesis under debate among scientists is that the virus would have slowly mutated in the body of a person with immunodeficiency, a process that lasted several months, until it reached the current version.

Why does it worry?

It is very contagious, “at a rate that we have not known until now with any other variant,” warned Tedros Adhanom Ghebreyesus, director general of the World Health Organization (WHO) on Tuesday.

This new version “is probably found in most countries,” he added. It has already been officially detected in 80.

South Africa, Denmark and the United Kingdom have already warned that cases are growing exponentially. Ómicron could be the dominant variant in Europe by mid-January, the president of the European Commission (EC), Úrsula von der Leyen, declared this week.

Will it definitely replace the delta variant? Scientists warn that both could coexist, as happens with certain variants of the flu virus, or that omicron will gain ground and then give delta an advantage again.

What impact for vaccines?

Current vaccines are already losing their efficacy against delta. Mutations in the omicron variant can significantly reduce antibody immunity to the virus.

Consequently, it can probably re-infect people who were previously affected by the virus, and contaminate a significant number of already vaccinated people.

Several recent laboratory studies support the latter hypothesis. The antibody rate drops dramatically to omicron among those vaccinated with Pfizer-BioNTech, Moderna, and even more so with AstraZeneca or Sinovac.

At the moment, a booster dose of the vaccines helps to strengthen the defenses. And in any case, the drugs are still effective, although the antibodies they generate are only part of the immune response.

“Cellular immunity”, which passes through cells called T lymphocytes, is much more difficult to detect.

A study published this week in South Africa suggests that the Pfizer-BioNTech vaccine is effective against severe forms of the omicron pandemic, including after the first two doses.

Ómicron also apparently poses difficulties for synthetic antibody treatments, especially among already hospitalized patients.

Less dangerous?

Clinical data from recent weeks suggest that omicron is no more dangerous than its predecessors, particularly delta. It is “almost a certainty,” US presidential adviser Anthony Fauci explained in early December.

The first omicron death occurred this week in the UK.

“We are concerned that people consider omicron as benign,” warned the boss of the WHO. “Even if it causes less severe symptoms, the number of cases could once again flood unprepared health systems.”