An exploration into the human immune response after a COVID-19 infection has revealed a surprising finding: women produce more antibodies to the coronavirus than men. The researchers, based at Tel Aviv University, found that age, the severity of COVID-19 symptoms, and the time since receiving a vaccine shot are also strong influencers of circulating antibody levels.
Antibodies are Y-shaped proteins that form a critical part of the immune system’s arsenal against pathogens. Once the body has been invaded by an infectious agent, short-lived cells known as plasmablasts produce some of the first antibodies to help resist infection. Subsequently, bone marrow plasma cells maintain long-term protection against germs, generating pathogen-specific antibodies for years after the initial infection.
In the context of COVID-19, neutralizing antibodies latch onto the spike protein of SARS-CoV-2, stopping virus particles from entering host cells and causing disease.
Researchers who were interested in what factors affect antibody production dynamics after COVID-19 examined over 25,000 blood samples taken from a cohort of study participants who had recovered from the disease. Women older than 51 were found to have higher SARS-CoV-2 antibody levels than men of matched ages. In men, rising antibody levels begin much earlier, starting around age 35. This phenomenon was hypothesized to be related to associated fluctuations in the sex hormones testosterone and estrogen.
Moreover, individuals who had received both doses of a COVID-19 vaccine had three times stronger antibody responses than those who had naturally recovered from the disease. The authors suggest that the patterns observed may point towards differences in the overall health of the immune system (young adults have stronger immunities than older people). However, peaks in antibody levels in seniors often point to an exaggerated immune response as a result of very severe COVID-19 symptoms.
The research was uploaded to the preprint server medRxiv.