Risk Factors for SARS-CoV-2 Seropositivity in a Health Care Worker Population

Background: Protecting health care workers (HCWs) during the coronavirus disease 2019 (COVID-19) pandemic is essential. Serologic testing can identify HCWs who had minimally symptomatic severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infections that were missed by occupational screening based on daily symptom and temperature checks. Recent studies report conflicting results regarding the impact of occupational factors on SARS-CoV-2 seropositivity amongst HCWs. Methods: The study population included all hospital workers at an academic medical center in Orange County, California. SARS-CoV-2 seropositivity was assessed from a fingerstick blood specimen using a coronavirus antigen microarray, which compares IgM and IgG antibodies against a panel of SARS-CoV-2 antigens with positive and negative controls to identify prior SARS-CoV-2 infection with 98% specificity and 93% sensitivity. Demographic, occupational, and clinical factors were surveyed and their effect on seropositivity estimated using multivariable logistic regression analysis. Results: Amongst 1,557 HCWs with complete data, SARS-CoV-2 seropositivity was 10.8%. Risk factors for increased seropositivity included male gender, exposure to COVID-19 outside of work, working in food or environmental services, and working in COVID-19 units. Amongst the 1,103 HCW who were seropositive but missed by occupational screening, additional risk factors included younger age and working in administration. Conclusions: SARS-CoV-2 seropositivity is significantly higher than reported case counts even amongst HCWs who are meticulously screened. Seropositive HCWs missed by occupational screening were more likely to be younger, work roles without direct patient care, or have COVID-19 exposure outside of work.