“As with all viruses, when you are infected with Sars-CoV-2, the immune system reacts and produces a response”, explains Professor Olivier Schwartz, head of the Viruses and Immunity unit at the Institut Pasteur. . “In particular in the form of the production of antibodies specific to the virus. “
Is this the case in all infected people?
“Yes, but the antibody level is more marked in those who have developed a severe form. No doubt because in these cases, there was a greater presence of virus, ”he explains.
Are people infected for the first time then protected?
“Several studies have shown that antibodies with so-called neutralizing activity are indeed produced by infected people,” says Professor Schwartz. This leads to protection of the organism against further exposure to the virus.
Is this protection final and permanent?
“The response decreases over time. What we know at the moment is that antibodies are still detectable between 3 and 6 months after the primary infection ”. This indicates that the body is protected by the immune system during this period. But “their quantity decreases over time,” he says. And “the detection of antibodies depends on the sensitivity of the tests”.
Several unknowns therefore remain as to the duration and efficacy over time of the immune response to this virus. It is important to remember, however, that not detecting antibodies in the body does not necessarily mean that the immune system is unable to defend itself. “It has a memory, which is manifested in particular by the ability of B lymphocytes – antibody producers – to react if they are again exposed to the virus by again producing specific antibodies”, explains Olivier Schwartz.
Several cases of reinfection have nevertheless been described?
“Indeed, 4 or 5 cases have been reported in the world on more than 45 million infected people”. As Inserm points out, “in the current state of knowledge, most scientists therefore agree that the phenomenon of reinfection remains rare”. And among these few cases “rigorously confirmed, only one, described in October 2020 in The Lancet, had presented more severe symptoms the second time, following reinfection”, continues Inserm.
Can a person infected for the first time transmit the virus?
“When you have had a first infection, that does not necessarily mean that you necessarily have so-called sterilizing immunity,” explains Olivier Schwartz. That is to say, which prevents the virus from settling, even momentarily, in the body. “It is possible that the virus colonizes the nasopharyngeal area, even if antibodies reactivate quickly and block the virus. But this does not prevent the presence and multiplication of the virus, even over a short time, ”he continues.
Certainly “the duration of contagiousness is shorter and the rate of virus produced is lower, but during this period the risk of transmission to others is not zero”. Not to mention that anyone, even immune, can be a carrier of the virus in the hands. “Maintaining barrier gestures is therefore necessary even if we have had a primary infection,” he concludes.
Source: Inserm, October 27, 2020 – interview with Prof. Olivier Schwartz, head of the Viruses and Immunity Unit at the Institut Pasteur, October 30, 2020