title: Pneumococcal serotype-specific antibodies persist through early childhood after infant immunization: follow-up from a randomized controlled trial.
abstract: BACKGROUND
  In a previous UK multi-center randomized study 278 children received three doses of 7-valent (PCV-7) or 13-valent (PCV-13) pneumococcal conjugate vaccine at 2, 4 and 12 months of age. At 13 months of age, most of these children had pneumococcal serotype-specific IgG concentrations ≥ 0.35 µg/ml and opsonophagocytic assay (OPA) titers ≥ 8.
  
  
  METHODS
  Children who had participated in the original study were enrolled again at 3.5 years of age. Persistence of immunity following infant immunization with either PCV-7 or PCV-13 and the immune response to a PCV-13 booster at pre-school age were investigated.
  
  
  RESULTS
  In total, 108 children were followed-up to the age of 3.5 years and received a PCV-13 booster at this age. At least 76% of children who received PCV-7 or PCV-13 in infancy retained serotype-specific IgG concentrations ≥ 0.35 µg/ml against each of 5/7 shared serotypes. For serotypes 4 and 18C, persistence was lower at 22-42%. At least 71% of PCV-13 group participants had IgG concentrations ≥ 0.35 µg/ml against each of 4/6 of the additional PCV-13 serotypes; for serotypes 1 and 3 this proportion was 45% and 52%. In the PCV-7 group these percentages were significantly lower for serotypes 1, 5 and 7F. A pre-school PCV-13 booster was highly immunogenic and resulted in low rates of local and systemic adverse effects.
  
  
  CONCLUSIONS
  Despite some decline in antibody from 13 months of age, these data suggest that a majority of pre-school children maintain protective serotype-specific antibody concentrations following conjugate vaccination at 2, 4 and 12 months of age.
  
  
  BACKGROUND
  ClinicalTrials.gov NCT01095471.
authors.affiliation: Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom.
authors.forename: Johannes
authors.initials: J
authors.lastname: Trück
authors.affiliation: Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Snape
authors.affiliation: Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom.
authors.forename: Florencia
authors.initials: F
authors.lastname: Tatangeli
authors.affiliation: Centre for Statistics in Medicine, University of Oxford, Oxford, United Kingdom.
authors.forename: Merryn
authors.initials: M
authors.lastname: Voysey
authors.affiliation: Centre for Statistics in Medicine, University of Oxford, Oxford, United Kingdom.
authors.forename: Ly-Mee
authors.initials: LM
authors.lastname: Yu
authors.affiliation: NIHR Wellcome Trust Clinical Research Facility and NIHR Respiratory Biomedical Research Unit, University Hospital Southampton NHS Foundations Trust and Faculty of Medicine and Institute for Life Sciences, University of Southampton, Southampton, United Kingdom.
authors.forename: Saul N
authors.initials: SN
authors.lastname: Faust
authors.affiliation: St. George's Vaccine Institute, St. George's, University of London, London, United Kingdom.
authors.forename: Paul T
authors.initials: PT
authors.lastname: Heath
authors.affiliation: Bristol Children's Vaccine Centre, University Hospitals Bristol NHS Foundation Trust and University of Bristol, Bristol, United Kingdom.
authors.forename: Adam
authors.initials: A
authors.lastname: Finn
authors.affiliation: Oxford Vaccine Group, Department of Paediatrics, University of Oxford and the NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Pollard
mesh_terms: D000907:Antibodies, Bacterial / Q000097:blood / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007117:Immunization, Secondary; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D008297:Male; D011008:Pneumococcal Infections / Q000276:immunology* / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000008:administration & dosage / Q000276:immunology; D065288:Serogroup; D013291:Streptococcus / Q000145:classification / Q000276:immunology*; D013296:Streptococcus pneumoniae / Q000276:immunology; D006113:United Kingdom; D014611:Vaccination
chemical_list: C538862:13-valent pneumococcal vaccine; D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; D022242:Pneumococcal Vaccines