Prospective surveillance study in a 1,400‐bed university hospital: COVID‐19 exposure at home was the main risk factor for SARS‐CoV‐2 point seroprevalence among hospital staff

Bahrs, Christina; Kimmig, Aurelia; Weis, Sebastian; Ankert, Juliane; Hagel, Stefan; Maschmann, Jens; Stallmach, Andreas; Steiner, Andrea; Bauer, Michael; Behringer, Wilhelm; Baier, Michael; Kesselmeier, Miriam; Richert, Cora; Zepf, Florian; Walter, Martin; Scherag, André; Kiehntopf, Michael; Löffler, Bettina; Pletz, Mathias W.

The Co‐HCW study is a prospective cohort study among hospital staff, including healthcare workers (HCWs) and administration staff, at the Jena University Hospital (JUH), Germany. The objectives of this study were to assess SARS‐CoV‐2 IgG seroprevalence, individual exposure risk factors and compliance of HCWs to wear personal protective equipment (PPE). After the first nosocomial COVID‐19 outbreak at JUH, mandatory masking was implemented on 20th March 2020. We evaluated point seroprevalence using two IgG detecting immunoassays and issued a questionnaire to assess COVID‐19 exposure, clinical symptoms and compliance to wear PPE. Antibody retesting was offered to participants with a divergent result of both immunoassays 5–10 weeks after the first test. Between 19th May and 19th June 2020, we analysed 660 participants [out of 3,228; 20.4%]. Among them, 212 participants (32.1%) had received a previous COVID‐19 test. Four of them (1.9%) reported a positive test result. After recruitment, 18 participants (2.7%) had SARS‐CoV‐2 antibodies in at least one immunoassay. Overall, 21 participants (3.2%) had any evidence of a past or current SARS‐CoV‐2 infection. Among them, 13 (61.9%) were not aware of direct COVID‐19 exposure and 9 (42.9%) did not report any clinical symptoms. COVID‐19 exposure at home (adjusted OR (aOR) with 95% CI: 47.82 (5.49, 416.62)) was associated with SARS‐CoV‐2 seroprevalence. We observed no evidence for an association between seroprevalence and exposure at work (aOR 0.48 (0.13, 1.70)) or with COVID‐19 risk area according to the working place (aOR for intermediate‐risk vs. high‐risk: 1.97 (0.42, 9.22), aOR for low‐risk versus high‐risk: 2.10 (0.40, 11.06); p = .655). Reported compliance of HCWs to wear PPE differed (p < .001) between working in high‐risk (98.3%) and in intermediate‐risk areas (69.8%). In conclusion, compared to administration staff, we observed no additional risk to acquire SARS‐CoV‐2 infections by patient care, probably due to high compliance to wear PPE.