The immunogenicity of Hemophilus influenzae type B polysaccharide-Neisseria meningitidis group B outer membrane protein complex vaccine in infants and young children.

Hemophilus influenzae type b polysaccharide-Neisseria meningitidis group B outer membrane protein complex vaccine was administered in a single dose to 38 children ages 24-53 mo (group 1) and to 78 children ages 12-23 mo (group 2) and in two doses to 84 children ages 2-11 mo (group 3). The geometric mean concentration of the capsular antibody before and after the vaccine regimen, respectively, were 0.35 microgram/ml and 12.59 micrograms/ml in group 1, 0.18 microgram/ml and 4.79 microgram/ml in group 2, and 0.15 microgram/ml and 3.80 micrograms/ml in group 3. After completing the vaccine regimen, concentrations of capsular antibody were greater than or equal to 0.15 microgram/ml in 199 (99.5%) of the 200 children and greater than or equal to 1.0 microgram/ml in 168 (84%) of the children. There were no serious and few minor adverse reactions to the vaccine. This vaccine is immunogenic in infants and young children.