Clinical burden of acute respiratory infections in children < 5 years in the emergency room: results from the first season (2023/24) of the RISE study

PURPOSE: To evaluate the role of acute respiratory infections (ARI) and its severity in emergency room (ER) visits in children. METHODS: In this study we assessed the attendance rate, hospitalization and pathogen epidemiology of ARI and proportion of lower/upper respiratory tract infections (LRTI/URTI) in a pediatric ER. From December 1, 2023 to May 30, 2024, patients aged < 60 months with ARI were recruited in a pediatric ER in Berlin. Nasopharyngeal multiplex real-time PCR was performed to identify respiratory pathogens. RESULTS: 5019 patients < 60 months attended the ER, thereof 2025 (40.4%) had ARI, 168 were included (median age 19 months). 100 (59.5%) had URTI and 68 (40.5%) had LRTI. Pathogens were detected in 152 cases (mono- and co-infections), with a total of 209 pathogens identified: 48 (22.5%) detections of respiratory syncytial virus (RSV), 31 (14.4%) of influenza (FLU), 55 (26.3%) rhinovirus (RV), 1 RSV/FLU (0.5%), and 75 (35.9%) of other viral pathogens. RSV was found significantly more often in LRTI-cases, FLU in URTI-cases. Children with RSV were significantly younger than those with FLU or RV (median ages in months: RSV, 11; FLU, 31; RV, 20.5; p < 0.001 for pairwise comparisons with RSV). The overall hospitalization rate was 25.6%, predominantly due to LRTI (79.1%). Especially in RSV LRTI was dominant (100%) compared to FLU (40.0%) and RV (66.7%). Hospitalization rates differed significantly between pathogen groups (RSV = 42.5%, FLU = 16.7%, RV = 23.7%, p = 0.003). CONCLUSIONS: Among young children RSV infections contribute significantly to ER visits as well as hospitalization in the ER cohort. Overall, prevention strategies of ARI may reduce patient burden in the ER and hospitalization.