Immunogenicity of a reduced schedule of pneumococcal conjugate vaccine in healthy infants and correlates of protection for serotype 6B in the United Kingdom.
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.
Goldblatt
David
D
Immunobiology Unit, UCL Institute of Child Health, London, United Kingdom. d.goldblatt@ich.ucl.ac.uk
Southern
Jo
J
Ashton
Lindsey
L
Andrews
Nick
N
Woodgate
Sarah
S
Burbidge
Polly
P
Waight
Pauline
P
Miller
Elizabeth
E
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*
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