How has the SARS-CoV-2 pandemic changed the epidemiology and management of acute bronchiolitis?

Objective: SARS-COV-2 pandemic profoundly impacted acute bronchiolitis epidemiology worldwide, especially respiratory syncytial virus (RSV) diffusion and the burden of disease, with remarkable implications on the management of health resources. We aimed to study the epidemiology and clinical course of bronchiolitis in the past 5 years in our region and to assess the trends that occurred during and after the SARS-COV-2 pandemic. Methods: We conducted an observational study including all children aged 0–2 years with bronchiolitis admitted to a tertiary children's hospital during the last 5 years. Demographic, clinical, and microbiological data were collected. Comparisons between patient subgroups were carried out. Results: A total of 647 patients admitted for bronchiolitis were included (median age 78 days). Molecular diagnostic tests were performed in 617 patients (95.4%) with RSV detected in 51.5% of patients in prepandemic years and 74.5% in pandemic years. Through the study period, we observed a progressive increase in the number of children requiring respiratory support, RSV infections, and children with a history of prematurity. Conversely, this was not true for mechanical ventilation, duration of respiratory support, intensive care unit admission, and length of stay. Conclusions: Clinical course and epidemiology of bronchiolitis showed a significant change through the study years with a heavy impact during the 2021–2022 season. The increase in the number of patients requiring respiratory support, although not associated with an increase in mechanical ventilation, may be explained by the higher prevalence of RSV. The change in epidemiology highlights the importance of surveillance systems to monitor RSV circulation, to plan prophylactic strategies, and prepare healthcare systems.