Risk of symptomatic Covid-19 among frontline healthcare workers

Background: Data are limited about severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) infection risk among frontline healthcare workers (HCWs) and whether personal protective equipment (PPE) mitigates this risk. Methods: We performed a prospective cohort study among 2,135,190 individuals using the COVID Symptom Tracker smartphone application to collect information among frontline HCWs and the general community since March 24, 2020 (United Kingdom) and March 29, 2020 (United States). We used Cox proportional hazards modeling to estimate multivariate-adjusted hazard ratios (aHRs) of a positive Covid-19 test through April 23, 2020. Results: Among 2,035,395 community individuals and 99,795 frontline HCWs, we documented 5,545 incident reports of a positive Covid-19 test over 34,435,273 person-days. Compared to the general community, frontline HCWs had an aHR of 11.6 (95% CI: 10.9 to 12.3) for a positive test. Frontline HCWs reporting inadequate PPE availability had a 23% increased risk of testing positive (aHR 1.23, 95% CI: 1.03 to 1.46). Compared to HCWs reporting adequate PPE who did not care for Covid-19 patients, HCWs caring for patients with documented Covid-19 had aHRs for a positive test of 4.91 (95% CI: 4.11 to 5.86) if they had adequate PPE and 5.94 (95% CI: 4.57 to 7.72) if they had inadequate PPE. Conclusions: Frontline HCWs had a significantly increased risk of symptomatic Covid-19 infection, which was highest among HCWs with inadequate access to PPE who cared for Covid-19 patients. However, adequate supplies of PPE did not completely mitigate high-risk exposures (ClinicalTrials.gov NCT04331509).