Palivizumab has recently been labeled by the U.S. Food and Drug Administration for prevention of respiratory syncytial virus (RSV) in high-risk infants and children. RSV is the most common cause of bronchiolitis and pneumonia in young children, with almost all infants affected at least once by two years of age. RSV usually causes a mild upper respiratory infection in otherwise healthy children, but hospitalization is common in premature infants and children with chronic immune deficiency, congenital heart disease and chronic lung disease.

No vaccine is currently available for RSV. Monthly intravenous injections of a hyper-immune globulin preparation decrease the incidence of RSV hospitalization in at-risk infants and children. However, its use is somewhat limited because of the inconvenience of monthly injections, concerns about use of a live attenuated vaccine and unexpected increases in adverse events in some children. Medical Letter consultants reviewed the available data on palivizumab.

A total of 1,500 premature infants and chronically ill children were given monthly intramuscular injections of palivizumab for five months at the start of the RSV season in a randomized, placebo-controlled study. Hospitalization was necessary in 4.8 percent of the patients in the treatment group and in 10.6 percent of the patients receiving placebo. The rate of hospitalization was also lower in both healthy premature infants and children with chronic lung disease taking palivizumab. Side effects were limited to increases in aminotransferase activity in the treatment group. The mortality rate was 1 percent or less in both groups.

The authors conclude that palivizumab significantly decreases the incidence of hospitalization for treatment of RSV in premature infants and in some young children with chronic lung disease but is a relatively expensive medication. The American Academy of Pediatrics has published detailed recommendations for use of palivizumab based on age, gestational age and the presence and severity of chronic lung disease or congenital heart disease. Although palivizumab appears to be relatively safe in selected children, the cost may be prohibitive.