Epidemiological and Clinical Characteristics of Bronchiolitis and the Impact of RSV Infection: A Five-Year Study in a Tertiary Pediatric Center in Central Romania

Background: Bronchiolitis, due to respiratory syncytial virus, is the most common cause of hospitalization and lower respiratory tract infections in infants and toddlers across the globe. Data on RSV epidemiology in Romania are limited and are mainly derived from national surveillance systems. Understanding regional trends in RSV bronchiolitis, its etiology, and its severity is important while assessing the potential impacts of future prevention measures. Methods: We conducted a retrospective cohort study including infants hospitalized with bronchiolitis between 2019 and 2023 in a tertiary pediatric center in Central Romania. Demographic, clinical, and treatment data were analyzed. Comparative analyses between RSV-positive and RSV-negative cases were performed among patients tested for RSV. Disease severity was assessed using oxygen saturation at admission and length of hospital stay. Results: A total of 2967 bronchiolitis hospitalizations were identified during the study period. After exclusion of 167 cases due to hospitalization <24 h or incomplete medical records, 2800 patients were included in the final analysis. The number of admissions decreased in 2020 (n = 301) compared to 2019 (n = 638), followed by an increase in 2021 (n = 463) and a peak in 2022 (n = 745), with a slight decrease in 2023 (n = 653). Among tested patients, RSV positivity increased from 14.4% in 2019 to 37.7% in 2022, then decreased to 27.4% in 2023. RSV-positive cases were more frequent in younger age groups, particularly those under 6 months of age. Compared to RSV-negative cases, RSV-positive bronchiolitis was associated with lower oxygen saturation at admission, and a longer hospital stay (<0.001), indicating a more severe clinical course. Treatment differences were also observed, with higher use of corticosteroids in RSV-positive patients (p < 0.002), while antibiotic use was similar between groups (p = 0.149). Conclusions: RSV infection was associated with a more severe clinical course in our cohort and continues to play a central role in the burden of disease. The variability observed in treatment practices also suggests that further efforts are needed to better align clinical management with current evidence-based recommendations.