Immunogenicity of a heptavalent pneumococcal conjugate vaccine in Apache and Navajo Indian, Alaska Native, and non-Native American children aged < 2 years

High rates of invasive pneumococcal disease have been described among infan ts living in various Native American communities. In this study, we evaluat ed the immunogenicity of a 7-valent pneumococcal vaccine consisting of sero types 4, 6B, 9V, 14, 18C, 19F, and 23F covalently linked to the outer membr ane protein complex of Neisseria meningitidis in Apache and Navajo Indian, Alaska Native, and non-Native American children. The vaccine was administer ed at ages 2, 4, and 6 months; a booster dose was given at age 15 months. L evels of serotype-specific immunoglobulin G (IgG) were measured by a standa rdized enzyme-linked immunosorbent assay. The responses after 3 primary dos es of vaccine were similar in all 3 groups of children, except for those to serotypes 14 and 23F One month after the booster dose, geometric mean conc entrations (GMCs) of serotype-specific Ige antibodies increased significant ly in all 3 groups of children, compared with GMCs of IgG antibodies to pne umococcal serotypes before the booster dose.