A joint study conducted by researchers from Tel Aviv University (TAU) and the Shamir Medical Center (Asaf Harofe) indicates that the level of COVID-19 antibodies in the human blood stream differs according to age groups, gender, symptoms, and time elapsed since vaccination.

The research examined the level of antibodies in over 26,000 blood samples taken from COVID-19 convalescents, as well as vaccinated and unvaccinated individuals. The study was published on July 8, 2021, on Medrxiv.

A difference was found between vaccinated women and men in the concentration of antibodies in the blood relative to both age and gender. In women, the level of antibodies begins to rise from the age of 51, and is higher than the levels found in men of similar age. This phenomenon may be related change in levels of the estrogen hormone, observed around this age, which affects the immune system. In men, a rise in antibody levels is seen at an earlier age, starting around 35. This may be related to changes in levels of the male sex hormone testosterone and its effect on the immune system.

The study also found that the immune response of individuals who have received two doses of the vaccine is much stronger than that of people who have recovered from COVID-19. In fact, the level of antibodies found in the blood of vaccinated persons was four times higher than that found in convalescents. Finally, the study concluded that a high concentration of antibodies in young adults is usually the result of a strong immune response, while in older people it typically indicates overreaction of the immune system associated with severe illness.

The study was conducted by Professor Noam Shomron, Head of the Computational Genomics Laboratory at TAU’s Sackler Faculty of Medicine and a member of the Edmond J. Safra Center for Bioinformatics, and Dr. Adina Bar Chaim from the Shamir Medical Center. The data were collected by Dr. Ramzia Abu Hamad of the Shamir Medical Center, and analysis was conducted by Guy Shapira, a PhD student at Professor Shomron’s laboratory.