Exposure to COVID-19 among unvaccinated healthcare personnel and risk for infection: a single-center retrospective study

Introduction: Characteristics of exposure and infection risk, are important in strategy development for infection control among healthcare workers (HCWs). Our objective was to investigate the characteristics of exposure of HCWs to SARS-CoV-2 and determine the risk of COVID-19 development.Methodology: This is a retrospective single-center cohort study, conducted between March and December 2020. Unvaccinated and exposed HCWs were asked to complete a standard form, including demographic data and characteristics of exposure(s). Exposures were stratified according to national guidelines. STROBE checklist was used.Results: Among a total of 4,385 healthcare workers, 1,483 HCWs (33.8%) with a total of 1,903 exposures to SARS-CoV-2 were identified. Median age was 31 (IQR: 26-40) years and 45.4% were male (N = 673). Following exposure, 78 HCWs became SARS-CoV-2-positive (attack rate: 3.9%) and secondary attack rate was 4/16. In terms of infection, exposure to SARS-CoV-2-positive HCWs posed a greater risk compared to contact with patients (8.9%, [n = 66] vs. 3.8% [n = 12], respectively, p = 0.003). PCR positivity rates were 11.5%, 6.3%, and 8.4% for low, medium, and high-risk contacts (p = 0.152). Median time to infection post-exposure was 7 (IQR: 4-13) days.Conclusions: Given the attack rates, there was no correlation between risk levels and PCR test positivity rates. There was no difference between HCWs with or without work restrictions, in terms of PCR positivity. Due to feasibility issues, prioritizing universally applied symptom screening and resource control strategies and suspending contact tracing and work restrictions, appear to be safe during high prevalence period.