Immunogenicity for 16 serotypes of a unique schedule of pneumococcal vaccines in a high-risk population

BackgroundA unique schedule of 7-valent pneumococcal conjugate vaccine (7PCV) at 2, 4 and 6 months of age and 23-valent pneumococcal polysaccharide vaccine (23PPV) at 18 months commenced for Australian Aboriginal infants in 2001.MethodsAnti-capsular IgG concentrations in vaccinated and non-vaccinated (historic control) infants were determined (blinded) by (22F absorbed) ELISA.ResultsOne month after dose 3 of 7PCV, geometric mean concentrations (GMCs) were >1.95 μg/ml and at least 89% of infants had IgG >0.35 μg/ml to all 7PCV serotypes. One month post-23PPV, IgG to 7PCV serotypes was >0.35 μg/ml for more than 96% infants (>1.3 μg/ml for at least 70%), and IgG to non-7PCV serotypes was >0.35 μg/ml for more than 50% infants (including serotype 6A, but not 12F (17%) or 19A (44%).Conclusion7PCV and 23PPV are immunogenic in this population.