Prospective Longitudinal Serosurvey of Healthcare Workers in the First Wave of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Pandemic in a Quaternary Care Hospital in Munich, Germany

Background. High infection rates among healthcare personnel in an uncontained pandemic can paralyze health systems due to staff shortages. Risk constellations and rates of seroconversion for healthcare workers (HCWs) during the first wave of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic are still largely unclear. Methods. Healthcare personnel (n = 300) on different organizational units in the LMU Munich University Hospital were included and followed in this prospective longitudinal study from 24 March until 7 July 2020. Participants were monitored in intervals of 2 to 6 weeks using different antibody assays for serological testing and questionnaires to evaluate risk contacts. In a subgroup of infected participants, we obtained nasopharyngeal swabs to perform whole-genome sequencing for outbreak characterization. Results. HCWs involved in patient care on dedicated coronavirus disease 2019 (COVID-19) wards or on regular non-COVID-19 wards showed a higher rate of SARS-CoV-2 seroconversion than staff in the emergency department and non-frontline personnel. The landscape of risk contacts in these units was dynamic, with a decrease in unprotected risk contacts in the emergency department and an increase on non-COVID-19 wards. Both intensity and number of risk contacts were associated with higher rates of seroconversion. On regular wards, staff infections tended to occur in clusters, while infections on COVID-19 wards were less frequent and apparently independent of each other. Conclusions. Risk of SARS-CoV-2 infection for frontline HCWs was increased during the first pandemic wave in southern Germany. Stringent measures for infection control are essential to protect all patient-facing staff during the ongoing pandemic.