Respiratory viral infections in children with asthma: do they matter and can we prevent them?

Ahanchian, Hamid; Jones, Carmen M; Chen, Yueh-sheng; Sly, Peter D

Much research interest has focused on the potential role respiratory viral infections play in the inception of asthma. It is well established that hospitalization for RSV bronchiolitis is a risk factor for asthma during childhood [37, 38] . Epidemiological studies have shown an increased risk of asthma with LRI caused by HRV. In the Childhood Origin of Asthma (COAST) birth cohort study, wheezing with RSV (odds ratio [OR], 2.6), HRV (OR, 9.8), or both HRV and RSV (OR, 10) was associated with increased asthma risk at age six years [7] . The Childhood Asthma Study (CAS) in Perth, Australia showed that wheezing with HRV or RSV in the first year of life was a risk factor (OR, 2.5) for current wheeze at five years of age [4] . Infant birth about four months before the winter virus peak carried the highest risk of developing asthma compared with birth 12 months before the peak [39] . The risk of asthma is increased by severe LRI (sLRI), especially in the presence of allergic sensitization in early life [4, 25] . There appears to be a synergistic interaction between viral infection and allergic sensitization, suggesting a "two hit" model for induction of persistent asthma. These data also provide a series of novel strategies for the primary prevention of asthma by prevention of either allergic sensitization or of sLRI in high risk children. This strategy is also supported in a study by Simoes et al. [40] , in which the use of palivizumab to prevent RSV infection decreased the risk of recurrent wheezing in nonatopic premature infants.