RSV immunoprophylaxis: does the benefit justify the cost?

Respiratory syncytial virus (RSV) is among the last viruses to cause major, predictable worldwide outbreaks of disease and for which no vaccine or broadly effective antiviral drug is available. Annually in the United States, RSV accounts for ∼125 000 hospitalizations, 2.1 million outpatient visits to a pediatrician’s office or an emergency department, and 250 deaths among children in the first years of life. In addition to the burden of acute disease caused by RSV, severe lower respiratory tract infection early in life is associated with recurrent wheezing during the first decade of life. The unresolved issue of the association between severe viral respiratory illness early in life and subsequent wheezing remains one of the more perplexing issues in pediatrics. Numerous studies have documented that infants hospitalized with viral lower airway disease (especially after rhinovirus or RSV infection) are more likely to experience recurrent wheezing in contrast to infants who do not experience severe bronchiolitis. Association of a susceptibility locus on chromosome 17q21, rhinovirus infection in early childhood, and wheezing indicates the existence of a complex interaction between a genetic predisposition and environmental factors. The unresolved question is whether a severe viral respiratory infection early in life alters normal lung development in a way that predisposes to subsequent wheezing or whether certain infants have a preexisting aberration of the immune response or of airway function that predisposes to both severe bronchiolitis and recurrent wheezing. If viral lower respiratory tract infections have a causal association with recurrent wheezing, prevention of infection should reduce the incidence of wheezing. If severe bronchiolitis simply identifies an infant who is predisposed to recurrent wheezing from a number of causes, prevention of RSV infection will have little or no impact on subsequent wheezing.