Population differences in antibody response to SARS-CoV-2 infection and BNT162b2 vaccination.

The concentration of SARS-CoV-2-specific serum antibodies, elicited by vaccination or infection, is a primary determinant of anti-viral immunity, which correlates with protection against infection and COVID-19. Serum samples were obtained from 25 897 participants and assayed for anti-SARS-CoV-2 spike protein RBD IgG antibodies. The cohort was composed of newly vaccinated BNT162b2 recipients, in the first month or 6 months after vaccination, COVID-19 patients and a general sample of the Israeli population. Antibody levels of BNT162b2 vaccine recipients were negatively correlated with age, with a prominent decrease in recipients over 55 years old, which was most significant in males. This trend was observable within the first month and 6 months after vaccination, while younger participants were more likely to maintain stable levels of serum antibodies. The antibody concentration of participants previously infected with SARS-CoV-2 was lower than the vaccinated and had a more complex, non-linear relation to age, sex and COVID-19 symptoms. Taken together, our data supports age and sex as primary determining factors for both the magnitude and durability of humoral response to SARS-CoV-2 infection and the COVID-19 vaccine. Our results could inform vaccination policies, prioritizing the most susceptible populations for repeated vaccination.