In some cases, the presence of antibodies is detectable in people infected up to thirteen months after their infection with Covid-19, emphasizes The world , not to mention the presence of “memory” cells which, in the event of reinfection, can quickly transform into cells secreting antibodies.
(Photo d’illustration) ( AFP / DENIS CHARLET )
This is rather reassuring news. While anti-Covid vaccination campaigns are in full swing, especially in Western countries, and let glimpse the light at the end of the tunnel, a series of recent studies reveal the durability of the immunity of former patients , even more after a vaccine injection, emphasizes The world.
While the first results underlined a strong decrease after a few months, a study pre-published in May (i.e. before peer review) and carried out on health personnel at Strasbourg University Hospital indeed shows that the presence of antibodies, which identify and neutralize the virus, persists in the body, up to thirteen months after contamination by Covid-19. “Antibodies would be produced in number as long as the pathogen is present in the body, before rapidly decreasing within seven months of infection, to finally stabilize at a lower but constant level “ , precise The world . “This is very good news”, rejoices Samira Fafi-Kremer, director of the Strasbourg Institute of Virology, at the origin of the study.
Several studies also show the presence in the body of infected people cells called “memory” B lymphocytes which, if re-infected, can quickly transform into antibody-secreting cells. Their number would remain relatively stable for up to twelve months after infection, according to the study by Michel Nussenzweig of Rockefeller University in New York, pre-published on May 9. “All the while, cells are undergoing mutations improving the quality of their immune response and their ability to produce neutralizing antibodies,” explains the daily.
These memory cells are also capable of adapting to variants , specifies Jean-Daniel Lelièvre, head of the clinical immunology and infectious diseases department at Henri-Mondor hospital, in Créteil (Val-de-Marne). “Overall, the response that is put in place after an infection seems to be of quality. All these data are rather reassuring on anti-SARS-CoV-2 immunity”, assures the latter.
Covid-19 + vaccine = “leaders of the immune response”
But not everyone enjoys the same immunity, and even infected people should be vaccinated , insists the American researcher Ali H. Ellebedy, who published a study in Nature May 24. This is confirmed by the work of Michel Nussenzweig, which highlights that vaccination increases B cells and antibodies , and “that recovering people who receive the (currently) available messenger RNA vaccines will produce antibodies and memory B cells which should protect against variants.” An injection of the vaccine would increase the body’s neutralizing capacity by about fifty times , precise The world.
“Clearly, the best setup is people who have had a moderate form of Covid-19, followed by a vaccine injection : these are the leaders of the immune response to SARS-CoV-2 “, comments Guy Gorochov, head of the center for immunology and infectious diseases at the Pitié-Salpêtrière hospital in Paris.” It is clear that vaccination boosts antibodies and memory, so we can hope to be protected for several years “ , insisted Samira Fafi-Kremer.
What then of vaccinated people who have never been infected? “The immunity of people who have just been vaccinated will probably not be as robust as that of people who are already infected , because the infection generates antibodies against several proteins of the virus “, explains Samira Fafi-Kremer.
A third dose of vaccine?
For Michel Nussenzweig’s team, the solution could lie in a third dose. “An additional boost at the appropriate time with available vaccines could cover most of the variants of concern.” , explains his team.
For Jean-Daniel Lelièvre, “there is a real relevance of the third dose” because “with a vaccine boost, we have antibodies against almost all the variants and the decrease of these antibodies is much longer”. A device that is not yet planned in France, the health authorities considering that the vaccination cycle is complete after two doses of vaccines (for Pfizer, AstraZeneca and Moderna sera, and only one for Janssen) or one dose after having been infected. However, the Ministry of Health ensures “anticipate all options”