title: Serotype-specific hyporesponsiveness to pneumococcal conjugate vaccine in infants carrying pneumococcus at the time of vaccination.
abstract: OBJECTIVE
  To determine whether pneumococcal carriage at the time of 11-valent pneumococcal conjugate vaccine (PCV-11) administration interferes with immune response in infants.
  
  
  METHODS
  A total of 1111 Filipino infants recruited into an immunogenicity and carriage study, nested in an efficacy trial, received PCV-11 or saline solution placebo at 6, 10, and 14 weeks of age. Antibody concentrations to the most frequently carried vaccine serotypes 6B, 19F, and 23F were measured by enzyme immunoassay from sera obtained at 18 weeks and 9 months of age. Serotype-specific antibody concentration was compared between groups of children among PCV-11 recipients stratified according to their carriage status at 6 weeks of age.
  
  
  RESULTS
  Antibody concentrations to 6B, 19F, and 23F were significantly lower at 18 weeks and 9 months of age among children who were carriers of the specific serotype at 6 weeks of age than among non-carriers of the serotype. The hyporesponsiveness was specific to the carried serotype. The specific antibody concentrations induced by PCV-11 among carriers did not differ significantly from those in placebo recipients, whereas the differences were highly significant among noncarriers.
  
  
  CONCLUSIONS
  Pneumococcal carriage, prevalent in Filipino infants, interferes with serotype-specific immune response to primary series of PCV and has potential implications for immunization programs.
authors.affiliation: National Institute for Health and Welfare, Helsinki and Oulu, Finland.
authors.forename: Merja
authors.initials: M
authors.lastname: Väkeväinen
authors.forename: Anu
authors.initials: A
authors.lastname: Soininen
authors.forename: Marilla
authors.initials: M
authors.lastname: Lucero
authors.forename: Hanna
authors.initials: H
authors.lastname: Nohynek
authors.forename: Kari
authors.initials: K
authors.lastname: Auranen
authors.forename: P Helena
authors.initials: PH
authors.lastname: Mäkelä
authors.forename: Gail
authors.initials: G
authors.lastname: Williams
authors.forename: Helena
authors.initials: H
authors.lastname: Käyhty
mesh_terms: D002353:Carrier State / Q000276:immunology*; D006801:Humans; D007223:Infant; D011008:Pneumococcal Infections / Q000276:immunology* / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000276:immunology*; D012703:Serotyping; D013296:Streptococcus pneumoniae / Q000145:classification*; D018074:Vaccines, Conjugate / Q000276:immunology*
chemical_list: D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate