Epidemiological analysis of respiratory and enteric outbreaks in long-term care homes in Ontario, Canada from 2020 to 2025. A retrospective longitudinal cross-sectional study.

BACKGROUND: Outbreaks of respiratory and enteric infections constitute a major threat to residents in long-term care (LTC) homes. The aim of the study was to analyze the epidemiological characteristics of respiratory and enteric outbreaks during and after the COVID-19 pandemic in order to provide a scientific basis for infection prevention and control strategies. METHODS: This retrospective, longitudinal cross-sectional study examined respiratory and enteric outbreaks across 25 LTC homes in Ontario, Canada from 2020 to 2025. The difference in pathogen distribution by month, season and year was examined. Outbreaks were categorized by phase: pandemic (2020-2022) and post-pandemic (2023-2025) and categorical distributions were analyzed using Chi-Square tests. RESULTS: The pandemic phase was dominated by SARS-CoV-2 with widespread suppression of other viruses, whereas the post-pandemic era saw a multi-pathogen resurgence. Post-pandemic, Influenza and RSV outbreaks peaked from October-March while Rhinovirus showed multiple seasonal peaks. The mean duration of outbreak ranged from 9.81 - 18.72 days and the mean attack rate ranged from 6.76 - 22.05%. CONCLUSIONS: The post-COVID-19 pandemic in LTC homes in Ontario is defined by a complex multi-pathogen burden. SARS-CoV-2 was not suppressed post-pandemic but remained as a major cause of outbreak in this setting with year-round circulation and Winter peaks. Influenza and RSV maintained Winter seasonality. Protecting residents in LTC homes requires a sustainable multi-pathogen surveillance strategy.