title: The immunogenicity of 7-valent pneumococcal conjugate vaccine versus 23-valent polysaccharide vaccine in adults aged 50-80 years.
abstract: BACKGROUND
  Infections with pneumococci are a major cause of morbidity and mortality in the elderly population. Although 23-valent pneumococcal polysaccharide vaccine (PPV) is recommended for elderly persons, the potential benefits of conjugate vaccine use in this age group remain unclear.
  
  
  METHODS
  We performed an open-label, randomized study that compared 7-valent pneumococcal conjugate vaccine (7vPnC) with PPV in 599 adults aged 50-80 years. Vaccinees received either 1 dose of 7vPnC or PPV or 1 dose of 7vPnC followed by a dose of 7vPnC or PPV 6 months later. Groups were stratified so they contained similar numbers of individuals aged 50-59, 60-69, and 70-80 years. Concentrations of immunoglobulin G specific for the serotypes in 7vPnC were measured before and 4-6 weeks after each vaccination and 1 year after enrollment.
  
  
  RESULTS
  Although baseline antibody levels were slightly lower in the older age groups, responses (fold rises) to either vaccine did not depend on age. Single-dose 7vPnC was superior for only 3 serotypes. Administration of a second dose of PPV or 7vPnC was similarly immunogenic in adults primed with 7vPnC, and titers after a second dose were similar to the first.
  
  
  CONCLUSIONS
  Pneumococcal vaccines retain their immunogenicity when administered into the eighth decade of life, but a second dose, when assessed by antibody titers alone, has little utility. 7vPnC vaccines do not lead to subsequent hyporesponsiveness.
  
  
  BACKGROUND
  http://www.clinicaltrials.gov/NCT00197821.
authors.affiliation: Institute of Child Health, University College London, UK. d.goldblatt@ich.ucl..ac.uk
authors.forename: David
authors.initials: D
authors.lastname: Goldblatt
authors.forename: Jo
authors.initials: J
authors.lastname: Southern
authors.forename: Nick
authors.initials: N
authors.lastname: Andrews
authors.forename: Lindsey
authors.initials: L
authors.lastname: Ashton
authors.forename: Polly
authors.initials: P
authors.lastname: Burbidge
authors.forename: Sarah
authors.initials: S
authors.lastname: Woodgate
authors.forename: Richard
authors.initials: R
authors.lastname: Pebody
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Miller
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D008297:Male; D008875:Middle Aged; D022242:Pneumococcal Vaccines / Q000008:administration & dosage / Q000276:immunology*; D018074:Vaccines, Conjugate / Q000008:administration & dosage / Q000276:immunology*
chemical_list: C414006:23-valent pneumococcal capsular polysaccharide vaccine; D007074:Immunoglobulin G; D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate