Serotype-specific avidity is achieved following a single dose of the 7-valent pneumococcal conjugate vaccine, and is enhanced by 23-valent pneumococcal polysaccharide booster at 12 months

Abstract

Aim: To evaluate whether the avidity of serotype-specific IgG to pneumococcal serotypes is enhanced by an increased number of doses of the 7-valent pneumococcal conjugate vaccine (PCV) in infancy or by a 12 month 23-valent pneumococcal polysaccharide vaccine (23vPPS) booster, and/or subsequent re-exposure to a small dose of pneumococcal polysaccharide antigens (mPPS) at 17 months. Methods: Fijian infants aged 6 weeks were recruited, stratified by ethnicity and randomized to 8 groups to receive 0, 1, 2, or 3 doses of PCV, with or without 23vPPS at 12 months. All children received mPPS at 17 months of age. Avidity of serotype-specific IgG for PCV serotypes in the first 12 months and for all 23..