Treatment and prevention options for respiratory syncytial virus infections.

Although the therapeutic antiviral agents ribavirin and amantadine ameliorate illness caused by influenza A and respiratory syncytial virus (RSV) in children, these agents are used infrequently because they are not cost-effective. Research currently is directed toward defining the high-risk groups for which these antiviral drugs should be used. Treatment of severe respiratory infection with specific immune globulin, either alone or in combination with antiviral drugs, is another therapeutic approach. Prevention of viral respiratory diseases is preferable because some lung damage occurs before the beginning of treatment, and damage resulting from the immune response may continue even after the virus is inhibited. As natural history and animal studies suggest, passive immunization can be achieved for neonates through active immunization of the mother during pregnancy. However, this approach is limited by the half-life of the transferred antibodies and the lack of antibody in premature infants. Standard immune globulin does not contain sufficient RSV neutralizing antibody titer to fully protect against severe RSV illness. Passive immunization with RSV immune globulin in infants and children has been shown to prevent or attenuate RSV in high-risk groups. Active immunization against some respiratory viruses has been achieved by administration of inactive virus (or their subunits), recombinant viral antigens, and live attenuated virus. Large trials are under way to determine the safety and immunogenicity of these vaccines for children in whom young age and serious underlying illness are significant barriers to primary immune response. The current research environment is suitable for the development of an immunization strategy to prevent many of the significant respiratory infections in children.