Occupational Risk Factors for SARS-CoV-2 Seropositivity in Healthcare Workers: Results of a Longitudinal Cohort

Objective The aim of the study is to evaluate COVID-19 risk factors among healthcare workers (HCWs) before vaccine-induced immunity. Methods We conducted a longitudinal cohort study of HCWs (N = 1233) with SARS-CoV-2 immunoglobulin G quantification by ELISA and repeated surveys over 9 months. Risk factors were assessed by multivariable-adjusted logistic regression and Cox proportional hazards models. Results SARS-CoV-2 immunoglobulin G was associated with work in internal medicine (odds ratio [OR], 2.77; 95% confidence interval [CI], 1.05-8.26) and role of physician-in-training (OR, 2.55; 95% CI, 1.08-6.43), including interns (OR, 4.22; 95% CI, 1.20-14.00) and resident physicians (OR, 3.14; 95% CI, 1.24-8.33). Odds were lower among staff confident in N95 use (OR, 0.55; 95% CI, 0.31-0.96) and decreased over the follow-up. Conclusions Excess COVID-19 risk observed among physicians-in-training early in the COVID-19 pandemic was reduced with improved occupational health interventions before vaccinations.