title: Systematic review of the effect of pneumococcal conjugate vaccine dosing schedules on vaccine-type invasive pneumococcal disease among young children.
abstract: BACKGROUND
  Pneumococcal conjugate vaccines (PCV) are being implemented globally using a variety of different schedules. The optimal schedule to maximize protection of vaccinated children against vaccine-type invasive pneumococcal disease (VT-IPD) is not known.
  
  
  METHODS
  To assess the relative benefit of various PCV dosing schedules, we conducted a systematic review of studies published in English from 1994 to 2010 (supplemented post hoc with studies from 2011) on PCV effectiveness against VT-IPD among children targeted to receive vaccine. Data on 2-dose and 3-dose primary series, both with and without a booster ("2+0," "2+1," "3+0" and "3+1"), were included. For observational studies using surveillance data or case counts, we calculated percentage reduction in VT-IPD before and after PCV introduction.
  
  
  RESULTS
  Of 4 randomized controlled trials and 31 observational studies reporting VT-IPD among young children, none evaluated a 2+0 complete series, 7 (19%) evaluated 2+1, 4 (11%) 3+0 and 27 (75%) 3+1. Most (86%) studies were from North America or Europe. Only 1 study (observational) directly compared 2 schedules (3+0 vs. 3+1); results supported the use of a booster dose. In clinical trials, vaccine efficacy ranged from 65% to 71% with 3+0 and 83% to 94% with 3+1. Surveillance data and case counts demonstrate reductions in VT-IPD of up to 100% with 2+1 (6 studies) or 3+1 (17 studies) schedules and up to 90% with 3+0 (2 studies). Reductions were observed as early as 1 year after PCV introduction.
  
  
  CONCLUSIONS
  These data support the use of 2+1, 3+0 and 3+1 schedules, although most data of PCV impact on VT-IPD among young children are from high-income countries using 3+1. Differences between schedules for impact on VT-IPD are difficult to discern based on available data.
authors: From the *Respiratory Diseases Branch, Division of Bacterial Diseases, National Center for Immunizations and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA; †Westat Inc., Rockville, MD; ‡Epidemic Intelligence Service, Centers for Disease Control and Prevention, Atlanta, GA; §International Vaccine Access Center, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD; and ¶Institute for Child Health, University College London, London, United Kingdom.
authors: Laura
authors: L
authors: Conklin
authors: Jennifer D
authors: JD
authors: Loo
authors: Jennifer
authors: J
authors: Kirk
authors: Katherine E
authors: KE
authors: Fleming-Dutra
authors: Maria
authors: M
authors: Deloria Knoll
authors: Daniel E
authors: DE
authors: Park
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; D006801:Humans; D007115:Immunization Schedule; D007223:Infant; D011008:Pneumococcal Infections / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000008:administration & dosage* / Q000276:immunology; D018074:Vaccines, Conjugate / Q000008:administration & dosage / Q000276:immunology
chemical_list: D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate