Respiratory Infection Burden and Work Attendance among Healthcare Workers; The CHILL Study (Common Cold Healthcare Workers Immunological Longitudinal Learning)

ObjectiveTo quantify the seasonal burden of acute respiratory viral infections among healthcare workers (HCWs), characterize virologic etiologies, and identify predictors of symptomatic illness and sick leave. MethodsWe conducted a prospective cohort study of HCWs during winter 2024-2025, with weekly surveys capturing acute respiratory infections (ARI) and sick leave. Nasal-throat multiplex PCR swabs were self-collected during symptomatic episodes. Incidence rate ratios (IRRs) for symptomatic episodes and sick days were estimated using Poisson regression; presenteeism was assessed among febrile episodes. ResultsAmong 655 HCWs, 400 (61.1%) reported [≥]1 symptomatic episode. Over 70,861 person-days, incidence rates were 1.34 symptomatic episodes and 0.82 sick days per 100 person-days. Among PCR-confirmed episodes (n=112), rhinovirus (45.5%) and influenza (23.2%) predominated. Female sex was associated with higher rates of symptomatic episodes (IRR 1.38, 95% CI 1.11-1.72) and sick days (IRR 2.55, 95% CI 1.62-4.00), while age >56 years was associated with lower rates of both. During febrile episodes, 38.8% (95% CI 31.5%-46.6%) reported working despite fever. ConclusionsARIs were common among HCWs and frequently resulted in sick leave, yet febrile presenteeism remained substantial, underscoring the need for strengthened respiratory virus prevention and occupational health policies.