Asthma and Lung Function in School-Aged Children After Severe RSV-A and RSV-B Bronchiolitis, Is There Any Difference?

INTRODUCTION: Human respiratory syncytial virus (HRSV) is a major cause of respiratory disease. It is classified into two antigenic subgroups. While several authors have studied the potential link between HRSV infection and later development of recurrent wheezing (RW) or asthma, no previous studies have assessed the role of HRSV subtypes. The aim of this study was to assess the medium-term respiratory morbidity in children and adolescents with prior severe bronchiolitis due to HRSV-A or HRSV-B infection. METHODS: From September 2023 to June 2025 an observational, prospective, cross-sectional follow-up study was conducted, including children and adolescents (5-18 years) with a history of hospital admission due to single HRSV infection. Patients underwent a structured questionnaire, measurement of exhaled nitric oxide, spirometry and skin prick testing for allergic sensitization. RESULTS: A total of 185 patients were recruited (129 HRSV-A, 56 HRSV-B). No differences in the variables regarding hospital admission for bronchiolitis were detected. The prevalence of current asthma in both groups was similar (HRSV-A 17.2% vs. 25.5%, p = 0.190). Patients with prior HRSV-B bronchiolitis reported more severe respiratory symptoms, particularly speech-limiting wheezing (HRSV-A 1.5% vs. HRSV-B: 8.9%, p = 0.039, OR 2.62 (95% CI: 1.3-5.4)) and more frequent nocturnal dry cough not associated with infections (HRSV-A: 7.7% vs. HRSV-B 16.9%, p = 0.044, OR: 1.78, (95% CI: 1.78-2.9)). Multivariate analysis revealed HRSV-B prior bronchiolitis to be an independent risk factor for medical diagnoses of asthma and nocturnal cough. CONCLUSIONS: Schoolchildren and adolescents with prior severe bronchiolitis due to HRSV-B have poorer respiratory outcome compared to those with HRSV-A, with more frequent intercrisis symptoms.