Covid-19: after the third dose of vaccine, will a fourth injection be needed? – LCI

Part of the population on their way to the third dose of vaccine … And soon the fourth? Since September, French people over 65 and those suffering from co-morbidities have been invited to return to a vaccination center, to a pharmacy or to their doctor, to take their booster dose. From December, everyone over 50 will be able to follow suit, for the third time in 2021.

This repeated vaccination schedule, caused by the decline in immune protection over time, appears to have two positive effects. First, according to results yet to be confirmed, the third dose could result in better protection than after the second injection. Above all, this one could last longer.

“The more you do booster doses, the more you will increase each time (the term of protection), it is known in immunology “, indicated in recent days on LCI Dr. Robert Sebbag, infectious disease specialist at the Pitié Salpêtrière hospital (Paris). For some vaccines, “you recall after a month, two months, then five years, ten years”, he recalled. “There is a cumulative protective effect of the antibodies.”

However, hard to believe that this third dose will protect the population ad vitam æternam. “Immunity due to coronaviruses is still transient”, tempers with LCI Professor Frédéric Adnet, head of emergencies at the Avicenne hospital (Bobigny). “What is closest to Sars-Cov-2 (the scientific name of the virus, Editor’s note), these are the benign diseases caused by other coronaviruses. However, these infections are recurrent, with temporary immunity. It is not clear why the immunity conferred by the vaccine would not follow the same pattern. “

Therefore, will a fourth dose necessarily be on the agenda in a few months if the epidemic continues, especially for the most vulnerable? “This is the most likely scenario”, continues Professor Adnet, even if it will take many months to learn more, thanks to the results of studies in real life. “We may need a regular booster, like with the flu.”