Publication date: Jul 29, 2025

The coronavirus disease 2019 (COVID-19) pandemic placed significant pressure on healthcare workers (HCWs) globally, exposing them to high risks of infection and psychological stress. This study assessed dynamic risks and protective factors for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among HCWs in Lima, Peru. We conducted the Peru Healthcare Worker COVID Cohort (PHCWCC), a prospective cohort study during the pre-COVID-19 vaccination period (August 2020-May 2021) and the post-vaccination period (August 2021-May 2022). Data included weekly nasal swabs for SARS-CoV-2 testing, reports on exposures, symptoms, perceived risks, and vaccination status. Incidence and factors associated with SARS-CoV-2 positivity were analyzed. Among 1369 HCWs, the infection rate increased from 1. 15 (95% confidence interval [CI]: .90-1. 14) to 1. 71 (95% CI: 1. 41-2. 05) per 1000 HCW-days between the pre- and post-vaccination phases (P = .01). Despite 97% receiving the primary vaccine series and 75% a booster, perceived high infection risk rose from 26% to 35% (P < .001). Close contact with infected colleagues remained a consistent risk factor (odds ratio [OR] = 2. 74, 95% CI: 1. 85-4. 05; P < .001). In the second phase, direct patient contact (OR = 1. 92, 95% CI: 1. 20-3. 08; P = .006) and patient care environments (OR = 2. 14, 95% CI: 1. 35-3. 40; P = .001) were linked to higher infection risk. Perceived infection risk was inversely associated with positivity (OR = 0. 76, 95% CI: 0. 63-0. 91; P = .003). Evolving infection risks highlight the need for sustained infection prevention, including during non-patient care activities. Fostering risk awareness may reduce infection rates and strengthen healthcare system resilience.

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