Seroprevalence of SARS CoV-2 antibodies in healthcare workers and administration employees: a prospective surveillance study at a 1,400-bed university hospital in Germany

Background: Healthcare workers (HCWs) are at particular risk to acquire SARS-CoV-2 infections. Aim: The objectives of this study were to compare SARS-CoV-2 IgG seroprevalence and compliance to wear personal protective equipment (PPE) between HCWs working within (high-risk) or outside (intermediate-risk) units treating suspected or confirmed COVID-19 patients. In addition, administration staff (low-risk) was included. Materials: Co-HCW is a prospective cohort study among employees at the Jena University Hospital, Germany. Since 16th March 2020, 50 SARS-CoV-2 inpatients and 73 outpatients were treated in our hospital. Mandatory masking was implemented on 20th March 2020. We here evaluated seroprevalence using two IgG detecting immunoassays, assessed COVID-19 exposure, clinical symptoms and compliance to wear PPE. Findings: Between 19th May and 19th June 2020 we analysed 660 employees [out of 3,228; 20.4%]. Eighteen participants (2.7%) had SARS-CoV-2 antibodies in at least one immunoassay. Among them, 13 (72.2%) were not aware of direct COVID-19 exposure and 9 (50.0%) did not report any clinical symptoms. We observed no evidence for an association between seroprevalence and risk area (high-risk: 2 of 137 HCWs (1.5%), intermediate-risk: 10 of 343 HCWs (2.9%), low-risk: 6 of 180 administration employees (3.3%); p=0.574). Reported compliance to wear PPE differed (p<0.001) between working in high-risk (98.3%) and in intermediate-risk areas (69.8%). Conclusion: No evidence for higher seroprevalence against SARS-CoV-2 in HCWs working in high-risk COVID-19 areas could be observed, probably due to high compliance to wear PPE. Compared to administration employees, we observed no additional risk to acquire SARS-CoV-2 infections by patient care.