Covid: the duration of the immune response would be greater in women than in men

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In one study, French researchers found after following hundreds of people who contracted a mild form of COVID-19 for several months that neutralizing antibodies are detectable in 84% of them up to 6 months after infection, but their rate it falls more rapidly in men than in women.

These results appear to support a longer duration of immunity in women than in men.

How well does our immune system remember the new coronavirus after infection? This crucial question is at the center of numerous scientific studies that focus on the characterization of the immune response during SARS-CoV-2 infection, to identify predictive markers of recovery or, conversely, of disease worsening. Despite this, the course of the antibody response to SARS-CoV-2 in infected individuals remains poorly characterized, and one of the most important questions is whether the production of protective or "neutralizing" antibodies can vary according to the degree of infection, but also according to sex or age.

In an attempt to elucidate these questions about the evolution of the immune response, teams from the University Hospital of Strasbourg and the Pasteur Institute followed 308 hospital staff members who developed mild forms of COVID-19 and whose infection was confirmed by RT- PCR, but did not require hospital management. Blood samples were collected at two time points, up to 6 months after the onset of symptoms. The presence of anti-SARS-CoV-2 antibodies was measured using three different techniques: two targeting the virus Spike (S) protein, the key that allows it to enter human cells, and a test targeting its nucleocapsid (NO ).

The antibodies are still present for several months after infection.

The neutralizing activity of these different antibodies was also measured with a test that measures the ability to block the virus. These measurements revealed that men over the age of 50, or those with a body mass index (BMI) greater than 25, had higher antibody levels one month after the onset of symptoms, compared to the rest of the individuals tested. . Then, between 3 and 6 months, anti-S antibodies and neutralizing antibodies persist, respectively, in 99% and 84% of individuals. In contrast, anti-N antibodies are only found in 59% of individuals, which according to the researchers shows that "depending on the test used, the seroprevalence of SARS-CoV-2 may be underestimated."

But in addition, the researchers found that between 3 and 6 months, the level of anti-S antibodies and that of neutralizing antibodies fall more rapidly in men than in women, regardless of age and BMI. A result that suggests that the duration of immunity against SARS-CoV-2 is longer in women than in men. "We are studying the ability of the immune system to produce protective antibodies after infection with SARS-CoV-2 and the duration of this immunity. Research suggests that in women, immunity is more durable than in men," they explain.

"Women keep their protective antibodies for a longer time"

While these results have not yet been validated with other studies in larger numbers of people, they are important for future evaluation of response to the vaccine. "The next step will be to study the response of the immune system after infection in a longer term and compare it, for example, with that obtained after vaccination when vaccines become available," the researchers add.

"Several studies have shown that the manifestations of COVID-19 are more severe in men than in women. This work suggests that this inequality persists after infection, as women retain their protective antibodies for longer."

The main hypotheses evoked are hormones (estrogen) and genetics, and more precisely sex chromosomes: women have two X chromosomes (XX) and men only one (XY). However, the X chromosome has an important influence on immunity, thus giving women an immune response that is slightly different from that of men.

The researchers plan to continue their work by studying in this same cohort "the other aspect of the immune response, the T-cell response, to obtain a global view of the anti-SARS-CoV-2 immune response and its evolution into mild forms of COVID-19 ", they conclude.

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