The Impact of Respiratory Syncytial Virus on Asthma Development and Exacerbation.

Asthma is a chronic inflammatory disorder of the lower airways clinically characterized by recurrent wheezing, breathlessness, cough, and dyspnea, and is the most prevalent chronic disease among children and adolescents. Respiratory viral infections are implicated in asthma inception and exacerbation, with respiratory syncytial virus (RSV) emerging as a key contributor. RSV is a leading cause of acute lower respiratory tract infections (LRTIs), particularly infant bronchiolitis, and is associated with a type-2-biased immune response, diminished interferon activity, epithelial barrier dysfunction, and altered airway microbiome. While the causal relationship between RSV and asthma remains debated, early-life RSV LRTIs are increasingly recognized as a significant risk factor for recurrent wheezing and asthma-like symptoms in childhood. This review comprehensively evaluates existing evidence on the long-term respiratory outcomes of infant RSV infection, elucidates the pathophysiological mechanisms connecting RSV infection to asthma development-such as immune dysregulation, chronic airway inflammation, and gene-environment interplay-and highlights novel preventive strategies. Recent advancements, such as maternal RSV vaccines and long-acting monoclonal antibodies, demonstrate efficacy in reducing severe RSV disease burden and subsequent wheeze in high-risk infants. By bridging clinical observations with mechanistic insights, this review underpins the development of future clinical therapies.