SARS-CoV-2 seroprevalence among 7,950 health-care workers in the Region of Southern Denmark. (THEIJID-D-21-01420R1)

von Huth, Sebastian; Lillevang, Søren Thue; Røge, Birgit Thorup; Madsen, Jonna Skov; Mogensen, Christian Backer; Coia, John Eugenio; Möller, Sören; Justesen, Ulrik Stenz; Johansen, Isik Somuncu

Objective Health-care workers (HCWs) carry a pronounced risk of acquiring severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We aimed to determine the seroprevalence and potential risk factors of SARS-CoV-2 infection among HCWs in the Region of Southern Denmark after the first pandemic wave in the spring of 2020. Methods Observational study conducted May-June 2020. SARS-CoV-2 IgG and IgM antibodies were measured in plasma. Participants were asked to complete a questionnaire consisting of demographic information, risk factors and COVID-19-related symptoms. Results A total of 7,950 participated. The seroprevalence of SARS-CoV-2 antibodies was 2.1% (95% CI 1.8-2.4). Seropositive participants were significantly older (mean age 48.9 years vs. 46.7 years in seronegative, P=0.022) and a higher percentage had experienced at least one symptom of COVID-19 (P<0.001). The seroprevalence was significantly higher among HCW working on dedicated COVID-19 wards (3.5%, OR 2.02 (95% CI 1.44-2.84). Seroprevalence was significantly related to 11-50 close physical contacts per day outside work (OR 1.54, 95% CI 1.07-2.22). Conclusion The prevalence of SARS-CoV-2 antibodies was low in HCWs. However, the occupational risk for contracting the infection is higher for those working on dedicated COVID-19 wards. Further, our results imply that attention should be paid to occupational risk factors in planning pandemic preparedness.