title: Lower immunoglobulin G antibody responses to pneumococcal conjugate vaccination at the age of 2 years after previous nasopharyngeal carriage of Streptococcus pneumoniae.
abstract: OBJECTIVE
  To determine whether nasopharyngeal pneumococcal carriage with serotypes 6B, 19F, or 23F interferes with immunoglobulin G (IgG) antibody responses to vaccination with 7-valent pneumococcal conjugate vaccine (PCV7) at the age 24 months.
  
  
  METHODS
  Blood samples were collected before and after a PCV7 challenge vaccination at age 24 months from subsets of children participating in a randomized controlled trial. Children previously had received two doses of PCV7 at 2 and 4 months, two plus one doses of PCV7 at 2, 4, and 11 months, or no dosage until 24 months. Nasopharyngeal swabs were cultured at for Streptococcus pneumoniae at age 6 weeks and at 6, 12, 18, and 24 months. IgG responses were determined with enzyme immunoassay.
  
  
  RESULTS
  Lower IgG responses against serotypes 6B, 19F, and 23F were observed on PCV7 challenge vaccination at 24 months in children who had received earlier PCV7 vaccinations and had been found positive for homologous carriage compared with non-carriers of these serotypes. Lower non-homologous IgG responses were observed after the PCV7 challenge at 24 months against serotype 6B after earlier 19F carriage and against serotype 19F after earlier 23F carriage compared with children who had not been positive for carriage of these serotypes.
  
  
  CONCLUSIONS
  Pneumococcal colonization with serotypes 6B, 19F, and 23F is associated with diminished immune responses against these serotypes on PCV7 vaccination at 2 years of age. Underlying mechanisms deserve further investigation.
authors.affiliation: Department of Pediatric Immunology and Infectious Diseases, Wilhelmina Children's Hospital, University Medical Center Utrecht, The Netherlands. g.d.rodenburg@umcutrecht.nl
authors.forename: Gerwin D
authors.initials: GD
authors.lastname: Rodenburg
authors.forename: Elske J M
authors.initials: EJ
authors.lastname: van Gils
authors.forename: Reinier H
authors.initials: RH
authors.lastname: Veenhoven
authors.forename: Debby
authors.initials: D
authors.lastname: Bogaert
authors.forename: Germie P J M
authors.initials: GP
authors.lastname: van den Dobbelsteen
authors.forename: Guy A M
authors.initials: GA
authors.lastname: Berbers
authors.forename: Elisabeth A M
authors.initials: EA
authors.lastname: Sanders
mesh_terms: D002353:Carrier State; D002675:Child, Preschool; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology*; D009666:Nose / Q000382:microbiology*; D010614:Pharynx / Q000382:microbiology*; D011008:Pneumococcal Infections / Q000382:microbiology* / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000276:immunology*; D012189:Retrospective Studies; D016037:Single-Blind Method; D013296:Streptococcus pneumoniae / Q000302:isolation & purification*
chemical_list: D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D007074:Immunoglobulin G; D022242:Pneumococcal Vaccines