Bronchiolitis before and after the SARS-CoV-2 pandemic: Twelve years of experience in a Spanish paediatric hospital

IntroductionAcute bronchiolitis is the main cause of hospitalization in children under 2 years of age, with a regular seasonality, mostly due to the respiratory syncytial virus. ObjectivesTo describe the epidemiology of bronchiolitis hospitalizations in our center in the last 12 years, and analyze the changes in clinical characteristics, microbiology, and adverse outcomes during the SARS-CoV-2 pandemic. MethodsObservational study including patients admitted for bronchiolitis between April 2010 and December 2021 in a Spanish tertiary paediatric hospital. Relevant demographic, clinical, microbiological, and adverse outcome variables were collected in an anonymized database. The pandemic period (April 2020 to December 2021) was compared to 2010-2015 seasons using appropriate statistical tests. ResultsThere were 2138 bronchiolitis admissions, with a mean of 195.6 per year between 2010 and 2019 and a 2-4-month peak between November and March. In the expected season of 2020, there was a 94.4% reduction of bronchiolitis hospitalizations, with only 11 cases admitted in the first year of the pandemic. Bronchiolitis cases increased from the summer of 2021 during a 6-month long peak, reaching a total of 171 cases. Length of stay was significantly shorter during the pandemic, but no differences were found in clinical and microbiological characteristics or other adverse outcomes. ConclusionsThe SARS-CoV-2 pandemic has modified the seasonality of bronchiolitis hospitalizations, with a dramatic decrease in cases during the expected season of 2020-2021, and an extemporaneous summer-autumn peak in 2021 with longer duration but similar patient characteristics and risk factors.

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Brief summary: This study investigated the epidemiology of bronchiolitis hospitalizations over the past 12 years in a Spanish pediatric hospital and analyzed the changes in clinical characteristics, microbiology, and adverse outcomes during the COVID-19 pandemic. The study found a 94.4% reduction in bronchiolitis hospitalizations during the expected season of 2020-2021, but a prolonged peak in the summer of 2021. The conclusions suggest that the COVID-19 pandemic has modified the seasonality of bronchiolitis hospitalizations, but patient characteristics and risk factors remain similar.