Prophylaxis of respiratory syncytial virus in Canada in 2003.

Passive immunization of high-risk children with the humanized monoclonal antibody palivizumab is the mainstay of respiratory syncytial virus (RSV) prophylaxis in Canada in 2003. This product appears to be safe, and it prevents the majority of RSV hospitalizations in infants born before 36 weeks gestational age, and about half in children under 24 months of age with hemodynamically significant congenital heart disease. However, the high cost of palivizumab and the fact that at least 12 infants need to be treated throughout RSV season to prevent one hospitalization make it difficult to determine the ideal indications for the product. Because these high-risk infants account for a minority of RSV hospitalizations, it is desirable to search for a prophylactic strategy that is practical to apply in all infants.