She was at the heart of the fight against the coronavirus in certain countries at the start of the pandemic. But today, the so-called "collective immunity" strategy is behind us. While many questions remain unanswered, researchers are becoming more and more familiar with Covid-19 and the hypotheses regarding post-infection immunity are beginning to be cleared up. Guest of "Sans Rendez-vous" this Tuesday on Europe 1, the resuscitator at the Parisian hospital Lariboisière Bruno Megarbane takes stock of new knowledge in this area.
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Is a second contamination possible?
"In the international [scientific] literature, there has never been a case of a second infection," said the specialist. "This suggests, even without definitive evidence, that the immunity acquired with a first infection is therefore protective. In addition, serological studies seem to show that all of the individuals who have had Covid-19 develop antibodies."
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Does immunity really protect?
If the body adapts its defenses after its first encounter with the coronavirus, does this materialize in an immunity guaranteeing that it can no longer be infected? Not necessarily, explains Bruno Megarbane. If the body does develop antibodies, as with any disease, "the rate and neutralizing nature of these is variable". Concretely, two patients will not develop similar immunity: it will be more or less protective and will last more or less long depending on the person.
In addition, "by analogy to other coronaviruses, where immunity declines over time, one might think that it is not at all definitive". It would last at most "a few months", according to the specialist.
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Could a second infection be as violent as the first?
If, as researchers at Princeton University say, Covid-19 will turn into "winter virus", the temporary immunity provided by a first infection would therefore be in no way guaranteed not to have one a second, a fortiori if it comes a year later. But doctor Bruno Megarbane is reassuring: even without antibodies, "the new infection would most likely be less significant, since there is still a certain level of knowledge of the virus by the human body".