title: Systematic review of the effect of pneumococcal conjugate vaccine dosing schedules on vaccine-type nasopharyngeal carriage.
abstract: BACKGROUND
  Pneumococcal conjugate vaccines (PCV) reduce nasopharyngeal carriage of vaccine type (VT) pneumococci, an important driver of vaccine programs' overall benefits. The dosing schedule that best reduces carriage is unclear.
  
  
  METHODS
  We performed a systematic review of English language publications from 1994 to 2010 (supplemented post hoc with studies from 2011) reporting PCV effects on VT carriage to assess variability in effect by dosing schedule.
  
  
  RESULTS
  We identified 32 relevant studies (36 citations) from 12,980 citations reviewed. Twenty-one (66%) evaluated PCV7; none used PCV10 or PCV13. Five studies evaluated 2 primary doses and 13 three primary doses. After the first year of life, 14 evaluated 3-dose primary series with PCV booster (3+1), seven 3 doses plus 23-valent polysaccharide booster "3+1PPV23," five "3+0," four "2+1," three "2+1PPV23" and two "2+0." Four studies directly compared schedules. From these, 3 primary doses reduced VT carriage more than 2 doses at 1-7 months following the series (1 study significant; 2 borderline). In a study, the 2+1 schedule reduced VT carriage more than 2+0 at 18, but not at 24 months of age. One study of a 23-valent pneumococcal polysaccharide vaccine booster showed no effect. All 16 clinical trials with unvaccinated controls and 11 observational studies with before-after designs showed reduction in VT carriage.
  
  
  CONCLUSIONS
  The available literature demonstrates VT-carriage reduction for 2+0, 2+1, 3+0 and 3+1 PCV schedules, but not for 23-valent pneumococcal polysaccharide vaccine booster. Comparisons between schedules show that 3 primary doses and a 2+1 schedule may reduce carriage more than 2 primary doses and a 2+0 schedule, respectively.
authors: From the *Epidemic Intelligence Service, Centers for Disease Control and Prevention, Atlanta, GA; †Respiratory Diseases Branch, Division of Bacterial Diseases, National Center for Immunizations and Respiratory Diseases, 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: Katherine E
authors: KE
authors: Fleming-Dutra
authors: Laura
authors: L
authors: Conklin
authors: Jennifer D
authors: JD
authors: Loo
authors: Maria Deloria
authors: MD
authors: Knoll
authors: Daniel E
authors: DE
authors: Park
authors: Jennifer
authors: J
authors: Kirk
authors: David
authors: D
authors: Goldblatt
authors: Cynthia G
authors: CG
authors: Whitney
authors: Katherine L
authors: KL
authors: O'Brien
mesh_terms: D002353:Carrier State / Q000382:microbiology / Q000517:prevention & control*; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D007115:Immunization Schedule; D007223:Infant; D009305:Nasopharynx / Q000382:microbiology*; D011008:Pneumococcal Infections / Q000382:microbiology / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000008:administration & dosage* / Q000276:immunology; D018074:Vaccines, Conjugate / Q000008:administration & dosage / Q000276:immunology
chemical_list: D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate