Humoral immune response in healthcare workers after two doses of a BNT162b2 mRNA vaccine in Yucatan, Mexico.

The antibody response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as well as the host immune response after vaccination and viral infection have shown to be highly heterogeneous. This is a case series study analysing humoral immune response and vaccination side effects after two doses of a BNT162b2 mRNA among healthcare workers (HCWs) in Mexico. All participants were scheduled for their two doses of mRNA BNT162b2 vaccine and provided information through a questionnaire: demographic characteristics, antibody serum titres and vaccination-related side effects. Blood samples were obtained for serology testing after the first and second doses of vaccine. No serious adverse effects due to vaccination were reported; nonetheless, non-medical HCWs reported more side effects after the second dose. The previous infection with SARS-CoV-2 boosted immune response after receiving the first vaccination (roughly 30 times higher than those without previous infection); nonetheless, after the second dose, the immune response did not show a higher titre as might be expected.