title: Immunogenicity of a reduced schedule of pneumococcal conjugate vaccine in healthy infants and correlates of protection for serotype 6B in the United Kingdom.
abstract: BACKGROUND
  Pneumococcal conjugate vaccine (PCV) was introduced in the United Kingdom immunization schedule in September 2006. This study was conducted to establish the immunogenicity of licensed PCV (Prevenar) at a reduced, 2 priming dose schedule (2+1) and to evaluate functional responses in the context of vaccine effectiveness.
  
  
  METHODS
  Infants were randomized to receive PCV at 2 and 3 months or 2 and 4 months of age. Boosters were administered at the same time as Haemophilus influenzae type B/meningococcal C conjugate and Measles, Mumps and Rubella or with Measles, Mumps and Rubella alone (www.ClinicalTrials.gov NCT00197808).
  
  
  RESULTS
  PCV at 2/3 months of age was poorly immunogenic and recruitment to this arm was terminated. PCV at 2/4 months of age resulted in lower than expected responses to serotypes 6B and 23F. Functional analysis of serotype 6B by OPA revealed that an enzyme-linked immunosorbent assay cutoff of 0.2 microg/mL was a better predictor of OPA positivity than a cut off of 0.35 microg/mL. PCV booster responses were excellent and no interference from concomitant vaccines was noted.
  
  
  CONCLUSIONS
  An interval of at least 8 weeks is required when starting PCV vaccination at 2 months of age although not all serotypes are equally immunogenic. Correlates of protection derived from enzyme-linked immunosorbent assay values may not be equally appropriate for all serotypes as illustrated by results for 6B in this study.
authors.affiliation: Immunobiology Unit, UCL Institute of Child Health, London, United Kingdom. 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: Lindsey
authors.initials: L
authors.lastname: Ashton
authors.forename: Nick
authors.initials: N
authors.lastname: Andrews
authors.forename: Sarah
authors.initials: S
authors.lastname: Woodgate
authors.forename: Polly
authors.initials: P
authors.lastname: Burbidge
authors.forename: Pauline
authors.initials: P
authors.lastname: Waight
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Miller
mesh_terms: D000907:Antibodies, Bacterial / Q000097:blood*; D016667:Bacterial Capsules / Q000008:administration & dosage / Q000276:immunology; D005260:Female; D018073:Haemophilus Vaccines / Q000008:administration & dosage / Q000276:immunology; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D007115:Immunization Schedule; D007117:Immunization, Secondary / Q000379:methods*; D007223:Infant; D008297:Male; D022542:Measles-Mumps-Rubella Vaccine / Q000008:administration & dosage / Q000276:immunology; D022401:Meningococcal Vaccines / Q000008:administration & dosage / Q000276:immunology; D022242:Pneumococcal Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D006113:United Kingdom; D014611:Vaccination / Q000379:methods*
chemical_list: D000907:Antibodies, Bacterial; D018073:Haemophilus Vaccines; C044237:Haemophilus influenzae type b polysaccharide vaccine; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022542:Measles-Mumps-Rubella Vaccine; D022401:Meningococcal Vaccines; D022242:Pneumococcal Vaccines; D011135:Polysaccharides, Bacterial; C437065:pneumococcal polysaccharide type 6; C410218:serogroup C meningococcal conjugate vaccine