Comparability of antibody response to a booster dose of 7-valent pneumococcal conjugate vaccine in infants primed with either 2 or 3 doses

In this cohort study we compared IgG antibody levels between infants immunized with 7-valent CRM197-conjugated pneumococcal vaccine (PCV-7) at 2,4 and 11 months and at 2, 3, 4 and 11 months of age,as measured by double adsorption ELISA. Pre- and post-booster levels following the 2 + 1 - and 3 + 1-dose schedule were comparable for 5 out of 7 serotypes except for serotypes 6B and 19F. The proportion of children reaching post-booster antibody thresholds were comparable except for 6B (>= 1.0 mu g/ml and >= 5.0 mu g/ml) and 19F (>= 5.0 mu g/ml). Surveillance studies are warranted for vaccine impact on 6B and 19F disease cases after reduced-dose PCV-7 schedules. (C) 2009 Elsevier Ltd. All rights reserved.