Respiratory syndromic surveillance for monitoring infection trends in long-term care facilities

Abstract Objective: To assess the surveillance characteristics of respiratory syndromic surveillance criteria and their usefulness for monitoring infection trends in long-term care (LTC) facilities. Design: Retrospective observational study. Setting: Two wards caring for children and adults with severe motor and intellectual disabilities in an LTC facility with 110 beds. Patients: Inpatients who underwent respiratory pathogen testing during febrile episodes between November 2022 and December 2025 were included. Episodes were defined as testing events associated with febrile periods and surveillance characteristics were assessed among tested episodes. Interventions: Surveillance criteria, derived from the patient-based component of the CARES strategy, were defined as fever ≥38.0°C lasting for ≥2 consecutive days accompanied by at least one respiratory symptom. Associations between surveillance-positive episodes and microbiologically confirmed respiratory infections were examined, and temporal trends were assessed. Sensitivity, specificity, positive predictive value, negative predictive value, and likelihood ratios were calculated as descriptive surveillance characteristics. Results: Overall, 1,467 episodes from 124 patients were analyzed, including 375 microbiologically confirmed episodes. Surveillance criteria identified 140 (9.5%) episodes, of which 87 (62.1%) were microbiologically confirmed, with 23.2% sensitivity (95% confidence interval, 19.0–27.8) and 95.1% specificity (95% confidence interval, 93.7–96.3). Surveillance-positive episodes demonstrated temporal patterns consistent with confirmed infections. Conclusions: Respiratory syndromic surveillance criteria demonstrated high specificity and captured temporal changes in microbiologically confirmed respiratory infections in LTC wards. Although not designed to identify every infection, simple signals, such as ≥2 surveillance-positive episodes per week, may facilitate monitoring respiratory infection activity and support timely infection prevention and control responses.