Clinical and epidemiological profile of infants with severe bronchiolitis before and after the COVID-19 pandemic.

OBJECTIVE: To describe clinical and epidemiological characteristics of infants hospitalized with severe Acute Viral Bronchiolitis (AVB) before and after the COVID-19 pandemic and to identify factors associated with intensive care unit (ICU) admission. METHODS: This retrospective study analyzed medical records of infants aged 1-24 months hospitalized for AVB at a private pediatric hospital in São Paulo, Brazil, in 2018-2019 and 2022-2023. Demographic and clinical variables were evaluated. Logistic regression was used to identify factors associated with ICU admission. RESULTS: A total of 2363 infants were included; 55.5% were male, and 56.7% were ≤6 months old. ICU admission was required in 51.8% of cases, and 45.3% required intensive respiratory support. RSV was identified in 44% of cases and was associated with greater severity, including higher ICU admission rates, increased need for intensive respiratory support, longer hospital stays, and more complications. Independent risk factors for ICU admission included RSV infection (OR 2.18; 95%CI: 1.8-2.6), age ≤ 6 months (OR 2.92; 95%CI: 2.4-3.5), oxygen saturation ≤ 93% at admission (OR 2.48; 95%CI: 2.0-3.0), and relevant personal history (OR 1.30; 95%CI: 1.1-1.6). Post-pandemic, infants were younger, had higher ICU admission rates, lower RSV detection, fewer complications, and increased corticosteroid use. Seasonal patterns were also altered, with an additional incidence peak observed in spring. CONCLUSIONS: RSV infection, younger age, and hypoxemia at admission were independently associated with ICU admission in infants hospitalized with severe AVB. Changes observed in the post-pandemic period included shifts in seasonality, patient profile, and management patterns.