Can infant bronchiolitis during respiratory syncytial virus season cause asthma?

Published Online: February 18, 2013

The rates of childhood asthma continue to increase, emphasizing the need to investigate what causes asthma and what can be done to prevent its development. One potentially modifiable risk factor that has been identified is respiratory syncytial virus (RSV) bronchiolitis in infancy. During the winter months, viral bronchiolitis in infancy is most often due to RSV. Previous studies demonstrate that infant RSV bronchiolitis is associated with an increased risk for asthma development but further research is needed to better characterize this relationship.

In an article recently published in The Journal of Allergy & Clinical Immunology (JACI), James et al analyzed data from a birth cohort to determine the burden of childhood asthma associated with prior infant bronchiolitis during RSV season. More than 260,000 infants cared for by either Northern California Kaiser Permanente, an integrated healthcare delivery system, or enrolled in Tennessee Medicaid were included in this study and followed until 6 years of age.

In both study populations nearly 50% of asthma cases among children with a history of infant bronchiolitis during RSV season were attributable to their infant illness. On a population level, 13% of asthma was associated with infant bronchiolitis during RSV season. The similar findings in the two populations are validating given the very significant geographic and demographic differences between the two study populations.

The authors’ findings suggest that at least 13% of asthma cases could be prevented by preventing infant RSV bronchiolitis. The mechanism to explain the association between infant RSV infection and asthma remains unclear, although studies in laboratory animals have provided causal evidence and mechanisms through which RSV causes a similar clinical and pathologic disease. The next step is to determine if preventing or altering host response to infant RSV infections leads to decreased asthma incidence and severity.


The Journal of Allergy and Clinical Immunology (JACI) is the official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.

AAAAI - American Academy of Allergy Asthma & Immunology