title: Systematic review of the effect of pneumococcal conjugate vaccine dosing schedules on prevention of pneumonia.
abstract: BACKGROUND
  Pneumonia is the leading cause of morbidity and mortality among children <5 years of age globally. Pneumococcal conjugate vaccines (PCVs) are known to provide protection against vaccine serotype pneumococcal pneumonia; uncertainty exists regarding the optimum PCV dosing schedule.
  
  
  METHODS
  We conducted a systematic review of studies published from 1994 to 2010 (supplemented post hoc with studies from 2011) documenting the effect of PCV dosing schedules on clinical and radiologically confirmed pneumonia, pneumococcal pneumonia and empyema among children of ages targeted to receive vaccine. Data on 2- and 3-dose schedules were included. Percent change of pneumonia incidence rates from baseline to most recent year post-PCV introduction was calculated.
  
  
  RESULTS
  We identified 42 primary citations that evaluated PCV schedules and pneumonia. Thirty-seven (88%) were from North America, Europe or Australia; 37 (88%) evaluated PCV7 and 1 (2%) PCV10. Two studies (both observational) compared multiple schedules within the study. We found evidence of reduced clinical and radiologically confirmed pneumonia incidence for all schedules, including 2+1 (1 nonrandomized trial, 5 observational studies), 3+0 (5 randomized trials, 2 observational studies) and 3+1 (5 clinical trials, 24 observational studies) schedules. The magnitude of disease impact did not differ among schedules. Evidence for impact on pneumococcal pneumonia and empyema varied.
  
  
  CONCLUSIONS
  All schedules (2+1, 3+0 and 3+1) reduced clinical and radiologically confirmed pneumonia. Quantifying differences in pneumonia disease impact between schedules was difficult due to heterogeneity among studies in design, case definition and population. These findings support World Health Organization recommendations for 3-dose schedules administered as either 3+0 or 2+1 regimens. Pneumonia impact data are still needed on expanded serotype PCV products, developing country settings and the role for a booster dose.
authors: From the *Respiratory Diseases Branch, Division of Bacterial Diseases, National Center for Immunizations and Respiratory Diseases; †Epidemic Intelligence Service, Centers for Disease Control and Prevention, Atlanta, GA; ‡International Vaccine Access Center, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD; §Westat Inc., Rockville, MD; and ¶Institute of Child Health, University College London, London, United Kingdom.
authors: Jennifer D
authors: JD
authors: Loo
authors: Laura
authors: L
authors: Conklin
authors: Katherine E
authors: KE
authors: Fleming-Dutra
authors: Maria
authors: M
authors: Deloria Knoll
authors: Daniel E
authors: DE
authors: Park
authors: Jennifer
authors: J
authors: Kirk
authors: David
authors: D
authors: Goldblatt
authors: Katherine L
authors: KL
authors: O'Brien
authors: Cynthia G
authors: CG
authors: Whitney
mesh_terms: D002675:Child, Preschool; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D007115:Immunization Schedule; D007223:Infant; D064887:Observational Studies as Topic; D022242:Pneumococcal Vaccines / Q000008:administration & dosage* / Q000276:immunology; D011018:Pneumonia, Pneumococcal / Q000517:prevention & control*; D016032:Randomized Controlled Trials as Topic; D018074:Vaccines, Conjugate / Q000008:administration & dosage / Q000276:immunology
chemical_list: C586648:10-valent pneumococcal conjugate vaccine; C538862:13-valent pneumococcal vaccine; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate