Jackson-Thompson BM, Goguet E, Laing ED, et al. - Via this prospective assessment of at-risk healthcare workers (HCWs), researchers aimed at examining the influence of pre-existing antibody or T cell responses to previous seasonal human coronavirus (HCoV) infections on immunological or clinical responses to SARS-CoV-2 infection or vaccination. During follow up, monthly serology analysis of IgM and IgG antibodies against the spike proteins of SARS-CoV-2 and the four major seasonal human coronavirus - HCoV-OC43, HCoV-HKU1, HCoV-229E, and HCoV-NL63, will be conducted in a cohort of 300 healthcare workers, confirmed negative for SARS-CoV-2 exposure upon study entry, for up to 1 year. The frequency of asymptomatic and pauci-symptomatic SARS-CoV-2 infection will be determined in this cohort. Findings from this study may inform whether pre-existing antibodies to these human coronaviruses are linked with altered COVID-19 disease course. Finally, evaluation will be performed examining if pre-existing immune responses to seasonal HCoVs influence the magnitude and duration of antibody and T cell responses to SARS-CoV-2 vaccination, adjusting for demographic covariates.