title: Efficacy and optimization of palivizumab injection regimens against respiratory syncytial virus infection.
abstract: OBJECTIVE
  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.
  
  
  OBJECTIVE
  To evaluate the effectiveness of current regimens for palivizumab injections across different cities and to design an optimized regimen.
  
  
  METHODS
  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).
  
  
  METHODS
  Different palivizumab injection regimens.
  
  
  METHODS
  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
  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.
authors.affiliation: School of Public Health, University of Illinois at Chicago2Department of Medicine, Loyola University Medical Center, Maywood, Illinois.
authors.forename: Alexander
authors.initials: A
authors.lastname: Gutfraind
authors.affiliation: School of Public Health, Yale University, New Haven, Connecticut.
authors.forename: Alison P
authors.initials: AP
authors.lastname: Galvani
authors.affiliation: Department of Integrative Biology, The University of Texas at Austin5Santa Fe Institute, Santa Fe, New Mexico.
authors.forename: Lauren Ancel
authors.initials: LA
authors.lastname: Meyers
mesh_terms: D061067:Antibodies, Monoclonal, Humanized / Q000008:administration & dosage* / Q000191:economics; D000914:Antibodies, Viral / Q000097:blood; D000998:Antiviral Agents / Q000008:administration & dosage* / Q000191:economics; D002675:Child, Preschool; D016527:Drug Costs; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007115:Immunization Schedule; D007223:Infant; D007234:Infant, Premature; D008962:Models, Theoretical; D000069455:Palivizumab; D011159:Population Surveillance; D018357:Respiratory Syncytial Virus Infections / Q000453:epidemiology / Q000517:prevention & control*; D012136:Respiratory Syncytial Viruses / Q000276:immunology; D014481:United States / Q000453:epidemiology
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D000914:Antibodies, Viral; D000998:Antiviral Agents; D000069455:Palivizumab