Prevention of bronchiolitis.

This review evaluates the current situation and long-term prospects for containment of human respiratory syncytial virus (HRSV) infection and bronchiolitis in infancy. The biology and immunopathology of HRSV infection are complex. Initial attempts to control HRSV infection using a conventional formalin-inactivated vaccine had the unexpected outcome that the disease was potentiated in some vaccinees experiencing natural HRSV infection at a later date. Much effort has been devoted to defining the nature of protective immunity, and several candidate sub-unit and live attenuated vaccines have been developed by empirical and semi-empirical routes, and most recently by reverse genetics. None has yet received approval for clinical use, and attention has switched from active to passive immunization. Both concentrated human immune globulin (RespiGam) and a humanized monoclonal antibody (Palivizumab) have been approved for clinical use. On grounds of cost-effectiveness these treatments are recommended only for treatment of high-risk infants. An effective antiviral is not yet available.