An institutional COVID-19 initiative: creation of a biobank and serological data analysis in pre- and...

The COVID-19 pandemic has left a legacy in the management of health emergencies, but sentinel surveillance was relatively underused, despite its significant role in decision-making during epidemics. Here we describe a sentinel surveillance for anti-SARS-CoV-2 serology carried out on a cohort of 395 individuals at a Brazilian institution, from October 2020 to December 2022. A total of 1,507 serum samples were analyzed for IgG and IgA against SARS-CoV-2 Spike (S) or nucleocapsid (N) proteins, in the pre- and post-vaccination periods. The latter included two doses of CoronaVac (group 1, G1), or ChAdOx-1 or BNT162b2 (group 2, G2), followed by heterologous booster doses. In the pre-vaccination phase, 26.5% of the participants showed IgG reactivity for S and 13.7% for N. After the vaccines' first dose, S IgG response was positive in 66.6% or 98% of G1 or G2 participants, respectively, whereas 100% of the participants showed S IgG positivity after the second dose, and S IgG and IgA after the booster. This initiative enabled the examination of viral transmission beyond hospital environments, which has rarely been explored, and established protocols for managing future emergencies. In addition, a serum bank and a comprehensive database are now available to the scientific community.