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Original Investigation
April 2015

Efficacy and Optimization of Palivizumab Injection Regimens Against Respiratory Syncytial Virus Infection

Author Affiliations
  • 1School of Public Health, University of Illinois at Chicago
  • 2Department of Medicine, Loyola University Medical Center, Maywood, Illinois
  • 3School of Public Health, Yale University, New Haven, Connecticut
  • 4Department of Integrative Biology, The University of Texas at Austin
  • 5Santa Fe Institute, Santa Fe, New Mexico
JAMA Pediatr. 2015;169(4):341-348. doi:10.1001/jamapediatrics.2014.3804

Importance  Infection with the respiratory syncytial virus (RSV) is the leading cause of hospitalizations in children, accounting for more than 90 000 hospitalizations every year in the United States. For children who are at risk for severe RSV infections, the American Academy of Pediatrics recommends immunoprophylaxis with a series of up to 5 injections of the antibody palivizumab administered monthly, beginning on November 1 of each year. However, many practitioners initiate injections at the onset of RSV season as indicated by local surveillance.

Objectives  To evaluate the effectiveness of current regimens for palivizumab injections across different cities and to design an optimized regimen.

Design, Setting, and Participants  We performed a mathematical modeling study of the risk for hospitalization due to RSV infection. The model accounted for the pharmacokinetics of the antibody, the timing of the injections, and seasonal patterns of RSV, including geographic and year-to-year variability. We used the model to estimate the efficacy of current regimens, including the American Academy of Pediatrics recommendation, and to design a more effective injection regimen, the optimized fixed start (OFS), which uses city-specific initiation dates. Participants were the approximately 700 000 individuals who had specimens tested for RSV by National Respiratory and Enteric Virus Surveillance System laboratories in 18 US cities from July 1, 1994, through June 30, 2011 (a total of 725 741 tests).

Interventions  Different palivizumab injection regimens.

Main Outcomes and Measures  The primary outcome measure was reduction in hospitalizations due to RSV infections. The secondary measures were cost (number of palivizumab doses) and duration of protection (in days).

Results  The American Academy of Pediatrics–recommended 5-injection regimen is expected to reduce hospitalization risk by a median of 2.7% (range, −2.2% to 6.1%) compared with the conventional regimen based on RSV surveillance. The 5-injection OFS regimen is expected to further reduce risk by a median of 6.8% (range, 4.9% to 14.8%), and the 4-injection OFS regimen is expected to achieve efficacy comparable to that of the conventional 5-injection regimen while reducing costs by 20%.

Conclusions and Relevance  Modified palivizumab regimens can improve protection for children at risk for severe outcomes of RSV infection and thereby lower rates of hospitalization due to RSV.