Variations in the incidence of bronchiolitis after the onset of SARS-CoV-2

Abstract

Introduction. A decrease has been observed during the 2020-2021 season in the incidence of hospitalizations for bronchiolitis. Changes in the evolution of the SARS-CoV-2 pandemic and in the application of preventive measures could be related to an increase in the incidence of severe bronchiolitis during the 2021-2022 season.

Objective. To determine the incidence of bronchiolitis hospitalizations in a tertiary hospital during the 2021-2022 season and to compare it with previous seasons.

Method. An observational, descriptive and ambispective epidemiological study. A tertiary hospital database was used to compare the incidence, etiology, and severity indicators of bronchiolitis hospitalizations. 3 cohorts were analyzed in epidemic times: the 2020-2021 season and the 2021-2022 season (prospective); and the 2018-2019 season (retrospective). A prospective cohort between the months of April and October 2021 was also analyzed.

Results. The cumulative incidence of hospitalizations was 113.6/10,000 children under 2 years of age in the pre-covid season; 3.6/10,000 in the 2020-2021 season; and 65.7/10,000 in the 2021-2022 season. The percentage of admissions in PICU was 36.6%, 0% and 30.8%, respectively. The cumulative incidence of hospitalizations in the non-epidemic period was 60.8/10,000, with 19% requiring admission to the PICU. The most frequent microorganism was the respiratory syncytial virus in all cohorts.

Conclusions. The incidence during the typically epidemic months of bronchiolitis drastically decreased the season in which SARS-CoV-2 appeared, noticeably increasing the next year, although without reaching the pre-pandemic incidence. A high incidence of bronchiolitis cases was observed between April and October 2021.