Acute bronchiolitis and respiratory syncytial virus seasonal transmission during the COVID-19 pandemic in Spain: A national perspective from the pediatric Spanish Society (AEP).

Introduction And Objectives: The COVID-19 pandemic and the widespread associated use of non-pharmaceutical interventions have impacted viral circulation and the incidence of respiratory tract infections. We compared Pediatric Emergency Department visits, bronchiolitis admissions, and respiratory syncytial virus (RSV) cases in 2020 with those documented for the preceding four years.

Methods: This was a retrospective multicentric national survey study, driven by the Pediatric Spanish Society, and gathering monthly data from Spanish hospitals between 1st January 2016 and 31st December 2020. An Interrupted Time Series Analysis and Poisson regression models were performed for each index.

Results: Thirty-eight hospitals representing most of the different regions of Spain participated. Compared to the preceding four years, in 2020, Pediatric emergency department visits significantly decreased immediately after initiation of the national lockdown. The median number of visits averted per month was 39,754 (IQR 26,539-50,065). RSV diagnoses during the 2020 winter season nearly disappeared with only 21 cases being documented among participating hospitals. The expected seasonal peak of bronchiolitis hospitalizations never occurred. The median number of admissions in 2020 averted per month was 100 (IQR 37-185) compared to 2016-2019. Only 3 hospitalized cases were RSV-confirmed. Reopening of schools and kindergarten was not associated with a remarkable increase in RSV cases or bronchiolitis hospitalizations.

Conclusion: A dramatic reduction of bronchiolitis admissions and near disappearance of RSV cases was observed in Spanish hospitals coinciding with the peak of the COVID-19 pandemic.