Abstract
Respiratory syncytial virus (RSV) continues to stand out as a compelling target for prevention. This ubiquitous virus is responsible for tens of thousands of pediatric hospitalizations per year in the United States, and is a dangerous land mine lying in the path of tenuously balanced premature infants, especially those with bronchopulmonary dysplasia (BPD). Although research directed at developing an RSV vaccine is in progress and candidates are undergoing testing in selected children,1 a vaccine for widespread use is not on the immediate horizon. Recent preventive efforts have focused on passive protection with preparations of RSV antibodies. Although RSV infections typically occur in infants and children with RSV antibodies in their blood, derived either from the mother or from previous RSV infection, there is now convincing evidence that RSV antibodies can protect against RSV infection. First, infants with RSV have lower levels of RSV neutralizing activity in their blood than comparison infants.2 Second, serum from RSV-immune animals protects recipient animals from RSV challenge, and the level of protection is correlated with the titer of neutralizing antibody transferred.3 Third, RSV-enriched human immune globulin (RSV-IVIG) protects human infants from RSV infection. Two major clinical trials, one sponsored by the National Institute of Allergy and Infectious Diseases (NIAID),4 and the other sponsored by the manufacturer and termed the PREVENT trial5 demonstrated that RSV-IVIG (RespiGam, Medimmune, Inc, Gaithersburg, MD) given by intravenous infusion in a dose of 750 mg/kg monthly during the RSV season reduced RSV hospitalizations by 41% to 63%. A common theme of all of these studies is that protection requires the right antibody at a protective level. Despite the reported efficacy of RSV-IVIG, several concerns have diminished enthusiasm for the product. Initially, licensure was delayed because of concerns at the Food and Drug Administration concerning the NIAID …
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