Immunogenicity after one, two or three doses and impact on the antibody response to coadministered antigens of a nonavalent pneumococcal conjugate vaccine in infants of Soweto, South Africa

Abstract

Children 80% of infants had >0.15 μg/ml antibody to six of the nine antigens, >70% to serotypes 18C and 23F and >50% to serotype 4. Geometric mean concentrations (GMCs) after one dose ranged from 0.27 μg/ml for serotype 23F to 2.98 μg/ml for serotype 1; >90% of infants had serotype-specific antibody >0.15 μg/ml except for serotypes 23F (70%) and 6B (80%). After two doses GMCs ranged from 1.14 μg/ml for serotype 23F to 5.68 μg/ml for serotype 1; >95% of infants had serotype-specific antibody >0.15 μg/ml and >75% had >0.5 μg/ml for all nine serotypes. GMCs after three doses ranged from 2.73 μg/ml for serotype 23F to 6.18 μg/ml for serotype 5; >98% of infants had serotype-specific antibody >0.15 μg/ml and >92% had >0.5 μg/ml for all nine serotypes. Antibody concentrations after three doses were significantly higher to Haemophilus influenzae type b-polyribosylribitol phosphate vaccine in children who received pneumococcal conjugate vaccine, but they had lower antibodies to pertussis toxin than controls. A single dose of this pneumococcal conjugate vaccine produces a potentially protective antibody response to most serotypes in the majority of children in this population.