Longitudinal analysis of severe acute respiratory syndrome coronavirus 2 seroprevalence using multiple serology platforms.

Current SARS-CoV-2 serological tests are based on the full-length spike (S), the receptor binding domain (RBD), or the nucleoprotein (NP) as substrates. Here, we used samples from health care workers (HCWs) to perform a longitudinal analysis of the antibody responses using a research-grade RBD and spike based enzyme-linked immunosorbent assay (ELISA), a commercial RBD and spike based ELISA, and a commercial NP based chemiluminescent microparticle immunoassay. Seroprevalence ranged around 28% early during the pandemic and a good correlation was observed between RBD and spike based ELISAs. Modest correlations were observed between NP and both RBD and spike based assays. The antibody levels in HCWs declined over time, however the overall seroprevalence measured by RBD and spike based assays remained unchanged, while the seroprevalence of NP reactive antibodies significantly declined. Moreover, RBD and spike based assays effectively detected seroconversion in vaccinees. Overall, our results consolidate the strength of different serological assays to assess the magnitude and duration of antibodies to SARS-CoV-2.