This is good news that the Strasbourg University Hospital revealed on May 20. The antibodies directed against the Spike protein (or protein S) of SARS-CoV-2 persist “up to 13 months after infection“, according to a study posted on the site MedRxiv, but which has not yet been published in a scientific journal.

1,309 people tested

This work followed for more than a year 1,309 people, of whom 393 had already contracted covid-19.

In all of these volunteers, the researchers evaluated the amount of “anti-S” antibodies. These molecules of the immune system are able to specifically recognize the S protein of the coronavirus and neutralize it, preventing the virus from attacking human cells.

Read also: Infection or vaccination, the same immunity?

97% of those who are cured keep their antibodies

In the group of people cured of covid, “one year after infection, 97% of individuals kept their anti-S antibodies“: indicates a CHU press release.

Not uniformly, however: the amount of antibodies directed against the virus spike protein “decreases faster in men than in women“, according to the researchers.

The risk of reinfection reduced by 96.7%

But that’s not all: antibodies that persist in the body for more than a year after infection seem to be quite effective. Indeed, the researchers compared the number of re-infections that occurred during the study in these healed people with the number of new infections in the control group of 916 people.

Result: the risk of contracting the disease is “reduced by 96.7% in those previously infected“, thanks to “long-term persistence of anti-S antibodies“.

Not effective against the South African variant

But are these antibodies also effective against variants of the coronavirus? According to Strasbourg researchers, the concentration of these antibodies in the body 13 months after infection makes it possible to neutralize “the wild virus (the historical strain of the virus, editor’s note) and the British variant, but not the South African “.

Get vaccinated, even after you have recovered

Last question: if the antibodies persist this long, is it really useful to get vaccinated when you have already cured of covid? Yes, according to this study which points out that vaccination, even at a single dose, “strengthens the protection against variants by significantly increasing“the amounts of antibodies.

Next step, for researchers: “extend the study to continue the follow-up at 18 months and 24 months to better assess the dynamics of the antibodies over the long term“, finally reveals Professor Samira Fafi-Kremer, head of the virology service of Strasbourg University Hospitals, in the press release.