[Consequences of COVID-19 pandemic over acute bronchiolitis hospitalizations in the center and east of Spain].

Introduction: Non-pharmaceutical interventions that have been implemented in southern hemisphere countries because of COVID-19 pandemic declaration in March 2020, have evidenced some unexpected changes in the way of spreading of many other viruses. This study as a part of ECEALHBA's Project, reports the consequences of COVID-19 pandemic over 2020-2021 bronchiolitis epidemic period in the Central and Eastern regions of Spain.

Method: Multicenter, observational, descriptive and ambispective study of admitted infants with the diagnosis of bronchiolitis in 16 Spanish hospitals involved in the investigation project. Five epidemic periods previous to COVID-19 pandemic, from 2015 to 2020, were compared with the current one, 2020-2021, in both a qualitative and quantitative manner.

Results: Total of 4643 infants were admitted to the participating hospitals along the study period. Pandemic season hospital admissions for bronchiolitis were 94.1% lower than in pre-pandemic period. December and January were peak months for bronchiolitis admissions during pre-pandemic period, but September was the peak month during pandemic year. There was a progressive decrease of admissions from this moment until the end of the follow up, in April 2021. Rhinovirus has been the commonest etiology for bronchiolitis in 2020-2021 epidemic period of bronchiolitis.

Conclusions: Some of the non-pharmaceutical interventions initiated because of COVID-19 pandemic are probably related to the dramatic decrease of bronchiolitis cases in 2020-2021 season. It would be rewarding to purpose novel research to clarify how these simple interventions can be useful, close to vaccines and antiviral drugs, to achieve the goal of avoiding the spread of respiratory viruses in pediatric population.