[en] While patient groups at risk for severe COVID-19 infections are now well identified, the risk factors associated with SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) transmission and immunization are still poorly understood. In a cohort of staff members of a Belgian tertiary academic hospital tested for SARS-CoV-2 antibodies during the early phase of the pandemic and followed-up after 6 weeks, 3 months and 10 months, we collected personal, occupational and medical data, as well as symptoms based on which we constructed a COVID-19 score. Seroprevalence was higher among participants in contact with patients or with COVID-19 confirmed subjects or, to a lesser extent, among those handling respiratory specimens, as well as among participants reporting an immunodeficiency or a previous or active hematological malignancy, and correlated with several symptoms. In multivariate analysis, variables associated with seropositivity were: contact with COVID-19 patients, immunodeficiency, previous or active hematological malignancy, anosmia, cough, nasal symptoms, myalgia, and fever. At 10 months, participants in contact with patients and those with higher initial COVID-19 scores were more likely to have sustained antibodies, whereas those with solid tumors or taking chronic medications were at higher risk to become seronegative.