Age-Dependent Risk of Bronchial Asthma Exacerbation in Respiratory Syncytial Virus Co-infection.

Introduction: Respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) are common viral etiologies of respiratory infections. Although co-infection with other respiratory pathogens is frequently observed, its clinical significance remains unclear.

Methods: We retrospectively analyzed 57,746 patients who underwent FILMARRAY®, a comprehensive multiplex polymerase chain reaction testing, between November 2020 and March 2023. Clinical features were compared between single infection and co-infection involving RSV or hMPV using χ² or Fisher's exact tests. Multiple logistic regression was performed to identify associations with bronchial asthma (BA) exacerbation, adjusting for age, sex, testing period, and RSV co-infection.

Results: Among RSV-positive patients, co-infection was associated with higher prevalence of BA history, wheeze, BA exacerbation, combined BA history and exacerbation, systemic steroid use, and age under 6 years compared to that with single infection. RSV co-infection with coronavirus, parainfluenza virus, adenovirus, and rhinovirus/enterovirus was particularly associated with BA exacerbation. Age under 6 years and RSV co-infection were identified as independent risk factors for BA exacerbation using multiple logistic regression. In contrast, no associations were observed in the hMPV co-infection.

Conclusion: RSV co-infection with other respiratory viruses increases the risk of BA exacerbation, especially in age under 6 years patients. Given the proven efficacy of RSV vaccine for adults and monoclonal antibody for high-risk children in preventing RSV-related lower respiratory tract disease, RSV-targeted prevention strategies for younger children appear effective in reducing respiratory disease burden.