Changes in Care in Spanish Pediatric Emergency Departments After the First Immunization With Nirsevimab

The aim of the study is to assess the changes in the pediatric care of patients seen in the Pediatric Emergency Departments (PED) during the bronchiolitis season following the introduction of immunization with a monoclonal antibody against RSV (nirsevimab).

An observational, retrospective, multicenter study was conducted, analyzing the Bronchiolitis Registry of the Spanish Society of Pediatric Emergency Medicine. This registry, containing data on bronchiolitis cases, was initiated in December 2022. A total of 30 hospitals participated, all of which are members of the Spanish Society of Pediatric Emergency Medicine. Data from a 26-day period in 2 bronchiolitis seasons (2022: preimmunization and 2023: postimmunization) were included. Variables regarding health care burden were recorded for both periods. Quantitative variables were described using mean and SD, and the Student t test was used for comparisons between the 2 periods.

Twenty-five hospitals from 11 autonomous communities were included with a mean of 47,811 PED visits/year (SD: 26,675). The number of bronchiolitis cases presenting to the PED and bronchiolitis-related admissions decreased by 41.6%(95% CI: 34.9%-48.2%) and 55.4% (95% CI: 46.6%-64.2%), respectively, while admissions for RSV bronchiolitis decreased by 60.3% (95% CI: 51.9%-68.7%). Admissions to pediatric intensive care units decreased by 81.3% (95% CI: 57.9%-100%). Furthermore, the occupancy rate in the pediatric intensive care units decreased by 30% (95% CI: 22.8%-37.3%), while a reduction of 22.4% (95% CI: 13.2%-31.5%) was observed in the occupancy rate of observation units. The number of bronchiolitis cases transferred to other hospitals decreased by 73.4% (95% CI: 29.0%-100%). Finally, there was a 60.9% (95% CI: 26.5%-95.3%) reduction in the need for high-flow oxygen therapy among bronchiolitis patients.

After the introduction of nirsevimab, a large portion of indicators related to the burden of care associated with bronchiolitis during its epidemic season decreased significantly.