The third dose of vaccine is presented as the best weapon to fight against the Omicron variant according to the leaders of BioNTech and Moderna, the American health authorities and the experts consulted by Le Devoir.
With the Delta variant, “the protective effect of the vaccines had certainly diminished, but remained sufficient”, recently affirmed the boss of BioNTech, Ugur Sahin, in a virtual press conference. However, Omicron poses new challenges: “32 of the 50 modifications identified so far concern the Spike protein”, which “could result in the body’s immune defenses no longer sufficiently recognizing the protein”.
A third dose “neutralizes” the Omicron variant, he added, while two doses are accompanied by a “significant” decrease in the effectiveness of the vaccine.
Same story with Moderna. The boss of the biotechnology company has declared in the American media that the loss of efficacy of the vaccines will be “significant” with the Omicron variant. “I cannot quantify it at the moment, we have to wait for the data, but all the scientists with whom I spoke […] told me “it’s not looking good”. “
Pfizer and BioNTech, like Moderna, also believe that two doses of their vaccine are still able to protect against the severe consequences of an Omicron infection. Ugur Sahin argued that a third dose achieves a level of protection of 95% efficacy “against any level of severity of the disease”.
“Giving a third dose with the current vaccine seems to increase the number of antibodies significantly and confer adequate protection against the virus”, confirms the professor and director of the Department of microbiology-infectiology and immunology of Laval University, Louis Flamand.
New vaccines in March
However, new vaccines adapted to the Omicron variant will soon enter production at Pfizer-BioNTech. A new generation adapted to this variant will be available from next March, according to Ugur Sahin. But large-scale production of these doses will not take effect quickly, and health authorities should not rely on these doses to stem Omicron, he warned. “The best is to get a third dose. “
Dr Antonio Fauci also said last week that these variant-adapted vaccines are unlikely to be needed.
Some pharmaceutical companies are working on a vaccine that would target parts of the virus other than the spike, such as the M protein. “A good idea”, according to Flemand, because “these proteins are less likely to mutate, because they are usually inside the virus and are not subjected to strong immunological pressure. They mutate less. “
Virologist Benoît Barbeau also believes that new vaccines could become commonplace, since the virus is expected to mutate again in the future. “Even if it sounds pessimistic, you can never be too defeatist when, every year, you discover a new strain of influenza and you realize that the vaccine is not suitable. “
This text is taken from our newsletter “The Coronavirus Mail” of December 13, 2021. To subscribe, click here.