in search of new generation vaccines


Development of the mRNA vaccine, at the BioNTech laboratory, in Marburg (Germany), in March 2021.

Etienne Decroly loves metaphors. In a few minutes of conversation, the research director at the CNRS, who has been tracking for two years, in his laboratory in Marseille, the evolution of SARS-CoV-2, has already tried three. “A contrasting picture”, “a two-sided coin”, “we are in the middle of the ford”. He explains himself. “You have to be clear. Who would have thought, two years ago, that we would have effective vaccines against serious forms in such a short time? Who would have thought that this vaccine protection would persist despite the mutations observed? Not many people. However, with the latest variants, the protection against infection is too limited and we do not know how long we will remain free from severe forms. We also do not know to what extent future mutations of the virus will affect this protection. »

In the scientific world, everyone shares, more or less, the diagnosis of the virologist. At the end of November, a study by the World Health Organization (WHO) and the European Center for Disease Prevention and Control (ECDC) estimated that vaccination alone had saved the lives of 470,000 people over 60 years, including 39,000 in France. “A marvel of modern science”, sang Henry Kluge, director of the European branch of the WHO.

However, on January 11, the WHO Technical Advisory Group on the composition of vaccines sang the counterpoint. “A vaccination strategy based on a multiplication of booster doses of the vaccine in its original form is unlikely to be suitable or sustainable. (…) We need vaccines against Covid-19 which, in addition to preventing serious forms of the disease and deaths, have a marked impact on the prevention of infections and on transmission. It would be good to get them straightened out. »

To tell the truth, the world of research did not wait for the instruction of the WHO to tackle the task. Dozens of teams have been working for months to try to develop these new vaccines. But what new vaccines? What purpose ? According to what principles? And when?

Adapt antigen to new variants

Chairman of the Vaccine Strategy Advisory Board, Alain Fischer says it without hesitation: “My first concern is to prepare for the likely recalls that will take place in the fall. » In January, his authority certainly advised against the administration of a fourth dose, noting that the third continued to protect well against severe forms, “but in two, three or six months, we don’t know and it is likely that the protection will decrease, he continues. You will probably need another reminder. But with what? It will be played between the current vaccine, a vaccine adapted to the Omicron variant, or perhaps to another variant, or even to a bivalent vaccine. The choice is very complicated, there are many uncertainties”.

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