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

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. 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. 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. 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.