Evaluation of the safety of palivizumab in the second season of exposure in young children at risk for severe respiratory syncytial virus infection

Drug Saf. 2003;26(4):283-91. doi: 10.2165/00002018-200326040-00005.


Background: Palivizumab reduces respiratory syncytial virus (RSV) hospitalisations in high-risk infants. Those with severe bronchopulmonary dysplasia may require two seasons of prophylaxis. There is concern that this humanised antibody might cause an adverse immune response in a second season of use.

Objective: To evaluate and compare the occurrence of anti-palivizumab antibodies and clinical adverse events in subjects receiving monthly palivizumab injections for a first and second season, and to assess frequency and severity of RSV disease in the two groups.

Design and patients: Subjects aged <or=2 years at severe risk for RSV disease were designated as first season (no previous palivizumab exposure) or second season subjects (received palivizumab in previous RSV season). Palivizumab injections (15 mg/kg) were administered monthly for up to 5 months. Anti-palivizumab antibody titres and serum palivizumab concentrations were measured; adverse events were recorded.

Results: No first (n = 71) or second (n = 63) season subjects experienced a significant anti-palivizumab antibody response (titre >or=1 : 80). Serum palivizumab concentrations were similar for the two groups. Nine (12.7%) first season and 8 (12.7%) second season subjects experienced one or more serious adverse events; most were respiratory and all were considered to be not or probably not related to palivizumab. No deaths occurred during the study.

Conclusions: Monthly palivizumab injections were not associated with adverse immune responses or adverse events in young children receiving palivizumab for one or two seasons. Children receiving palivizumab for a second season did not experience more severe adverse events than those receiving it for the first time.

Publication types

  • Comparative Study
  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Monoclonal / adverse effects*
  • Antibodies, Monoclonal / blood
  • Antibodies, Monoclonal / therapeutic use
  • Antibodies, Monoclonal, Humanized
  • Chi-Square Distribution
  • Drug Administration Schedule
  • Drug Evaluation / methods
  • Female
  • Humans
  • Infant
  • Infant, Newborn
  • Male
  • Palivizumab
  • Respiratory Syncytial Virus Infections / blood
  • Respiratory Syncytial Virus Infections / drug therapy*
  • Respiratory Syncytial Virus Infections / immunology
  • Risk Factors
  • Seasons*
  • Statistics, Nonparametric


  • Antibodies, Monoclonal
  • Antibodies, Monoclonal, Humanized
  • Palivizumab