Characterizing the SARS-CoV-2 antibody response and associations with patient factors: Serological profiling of participants enrolled in the GENCOV study

Characteristics of the SARS-CoV-2 antibody response associated with COVID-19 severity and protective immunity remain unclear. Here we assessed SARS-CoV-2 antibody responses in GENCOV participants to identify differences following COVID-19 diagnosis and/or vaccination. Blood samples were collected 1-, 6- and 12-months following SARS-CoV-2 infection and/or vaccination. Participants who were vaccinated, and to a greater extent those who were both infected and vaccinated, had significantly elevated anti-spike antibody titers compared to unvaccinated participants. In unvaccinated participants, increasing age and illness severity were associated with significantly higher antibody titers. Participants who were vaccinated after infection (hybrid immunity) had consistently higher antibody titers compared to participants who were infection-naïve or vaccinated prior to their infection ( breakthrough infections) suggesting that timing of vaccination played a role in the antibody response. At all time points, receiving more vaccine doses and having a more recent vaccination were strongly associated with higher antibody titers. These findings highlight various patient factors, including vaccination, which contribute to maintaining robust and durable SARS-CoV-2 antibody responses.