title: Pneumococcal antibody concentrations and carriage of pneumococci more than 3 years after infant immunization with a pneumococcal conjugate vaccine.
abstract: BACKGROUND
  A 9-valent pneumococcal conjugate vaccine (PCV-9), given in a 3-dose schedule, protected Gambian children against pneumococcal disease and reduced nasopharyngeal carriage of pneumococci of vaccine serotypes. We have studied the effect of a booster or delayed primary dose of 7-valent conjugate vaccine (PCV-7) on antibody and nasopharyngeal carriage of pneumococci 3-4 years after primary vaccination.
  
  
  RESULTS
  We recruited a subsample of children who had received 3 doses of either PCV-9 or placebo (controls) into this follow-up study. Pre- and post- PCV-7 pneumococcal antibody concentrations to the 9 serotypes in PCV-9 and nasopharyngeal carriage of pneumococci were determined before and at intervals up to 18 months post-PCV-7. We enrolled 282 children at a median age of 45 months (range, 38-52 months); 138 had received 3 doses of PCV-9 in infancy and 144 were controls. Before receiving PCV-7, a high proportion of children had antibody concentrations >0.35 µg/mL to most of the serotypes in PCV-9 (average of 75% in the PCV-9 and 66% in the control group respectively). The geometric mean antibody concentrations in the vaccinated group were significantly higher compared to controls for serotypes 6B, 14, and 23F. Antibody concentrations were significantly increased to serotypes in the PCV-7 vaccine both 6-8 weeks and 16-18 months after PCV-7. Antibodies to serotypes 6B, 9V and 23F were higher in the PCV-9 group than in the control group 6-8 weeks after PCV-7, but only the 6B difference was sustained at 16-18 months. There was no significant difference in nasopharyngeal carriage between the two groups.
  
  
  CONCLUSIONS
  Pneumococcal antibody concentrations in Gambian children were high 34-48 months after a 3-dose primary infant vaccination series of PCV-9 for serotypes other than serotypes 1 and 18C, and were significantly higher than in control children for 3 of the 9 serotypes. Antibody concentrations increased after PCV-7 and remained raised for at least 18 months.
authors.affiliation: Medical Research Council (MRC), The Gambia Unit, Banjul, The Gambia.
authors.forename: Adebayo K
authors.initials: AK
authors.lastname: Akinsola
authors.forename: Martin O C
authors.initials: MO
authors.lastname: Ota
authors.forename: Godwin C
authors.initials: GC
authors.lastname: Enwere
authors.forename: Brown J
authors.initials: BJ
authors.lastname: Okoko
authors.forename: Syed M A
authors.initials: SM
authors.lastname: Zaman
authors.forename: Mark
authors.initials: M
authors.lastname: Saaka
authors.forename: Ekpedeme D
authors.initials: ED
authors.lastname: Nsekpong
authors.forename: Aderonke A
authors.initials: AA
authors.lastname: Odutola
authors.forename: Brian M
authors.initials: BM
authors.lastname: Greenwood
authors.forename: Felicity T
authors.initials: FT
authors.lastname: Cutts
authors.forename: Richard A
authors.initials: RA
authors.lastname: Adegbola
mesh_terms: D000907:Antibodies, Bacterial / Q000276:immunology*; D000917:Antibody Formation / Q000276:immunology; D002353:Carrier State / Q000276:immunology* / Q000382:microbiology*; D002648:Child; D002675:Child, Preschool; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D007117:Immunization, Secondary; D007074:Immunoglobulin G / Q000276:immunology; D007223:Infant; D009305:Nasopharynx / Q000382:microbiology; D011008:Pneumococcal Infections / Q000276:immunology / Q000382:microbiology; D022242:Pneumococcal Vaccines / Q000008:administration & dosage / Q000276:immunology*; D016032:Randomized Controlled Trials as Topic; D013296:Streptococcus pneumoniae / Q000276:immunology*; D014611:Vaccination
chemical_list: D000907:Antibodies, Bacterial; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D007074:Immunoglobulin G; D022242:Pneumococcal Vaccines