title: A randomized, double-blind, placebo-controlled trial to evaluate the prime-boost strategy for pneumococcal vaccination in adult liver transplant recipients.
abstract: BACKGROUND
  The 23-valent pneumococcal polysaccharide vaccine (PPV23) is recommended for disease prevention in solid-organ transplant recipients, but it may have suboptimal immunogenicity. It may be possible to enhance immunogenicity by priming the recipient with the 7-valent pneumococcal conjugate vaccine (PCV7), followed by boosting with PPV23.
  
  
  METHODS
  We randomized adult liver transplant recipients to receive either (1) PCV7 followed by a PPV23 booster 8 weeks later (the "primed" group) or (2) placebo followed by a standard single dose of PPV23 (the "unprimed" group). Quantitative and functional antibody titers for 7 serotypes contained in both vaccines were measured at baseline, 8 weeks after enrollment, and 16 weeks after enrollment. Of 130 randomized patients, 113 completed the study.
  
  
  RESULTS
  At week 16, response to at least 1 serotype was seen in 48 (85.7%) of 56 and 52 (91.2%) of 57 patients for the primed and unprimed groups, respectively (P=not significant). The mean number of serotypes to have responded (+/-SD) was 307+/-2.3 and 4.4+/-2.2 for the primed and unprimed groups, respectively (P=not significant). Functional antibody titers, which were measured with use of the opsonophagocytic assay, were also similar in both groups.
  
  
  CONCLUSIONS
  The immunogenicity of pneumococcal vaccination was not enhanced by the prime-boost strategy, compared with vaccination with PPV23 alone. Administration of a single dose of PPV23 should continue to be the standard of care for adult liver transplant recipients.
  
  
  BACKGROUND
  NCT00152802 (http://www.clinicaltrials.gov).
authors: Transplant Infectious Diseases, University of Alberta, Edmonton, Canada. deepali.kumar@ualberta.ca
authors: Deepali
authors: D
authors: Kumar
authors: Maggie Hong
authors: MH
authors: Chen
authors: Gary
authors: G
authors: Wong
authors: Isabel
authors: I
authors: Cobos
authors: Brenda
authors: B
authors: Welsh
authors: Deborah
authors: D
authors: Siegal
authors: Atul
authors: A
authors: Humar
mesh_terms: D004311:Double-Blind Method; D005260:Female; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D016031:Liver Transplantation; D008297:Male; D008875:Middle Aged; D011008:Pneumococcal Infections / Q000517:prevention & control; D022242:Pneumococcal Vaccines / Q000008:administration & dosage / Q000627:therapeutic use*
chemical_list: C414006:23-valent pneumococcal capsular polysaccharide vaccine; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022242:Pneumococcal Vaccines