Risk of SARS-CoV-2 infection in healthcare workers with insufficient use of personal protective equipment in Denmark

Aim The aim was to evaluate the role of insufficient use of personal protective equipment (PPE) in SARS-CoV-2 transmission risk for healthcare workers (HCW) during the COVID-19 pandemic.Methods Prospective study within the COBRA cohort, including 15,127 HCW. Daily assessment of insufficient use of PPE, defined as self-reported PPE failure or noncompliance, in relation to SARS-CoV-2 infection ascertained by polymerase chain reaction (PCR) test. Statistical analysis involved calculating incidence rate ratios with 95% confidence intervals (CI).Results The included HCW contributed to 780,515 risk days including 67,723 d (8.7%) with insufficient PPE use and 133 events (positive PCR test). Self-reported insufficient use of PPE was slightly associated with infection with COVID-19 in HCW, but the data were statistically consistent with parameter values ranging from a protective effect to a to a doubling in risk (IRR 1.3, 95% CI 0.8; 2.3). Sensitivity analyses restricted to high-risk departments and to a period with a sufficient supply of PPE and a fully developed testing system, respectively, confirmed these findings.Conclusion Insufficient use of PPE among HCW during the pandemic in Denmark was uncommon but associated with a slightly increased risk of COVID-19 among HCW. However, the findings are uncertain due to the limited number of cases and the potential for misclassification bias stemming from the self-reported nature of the exposure.