Antibody responses after immunization with polyvalent pneumococcal vaccine containing 10, 25, or 50 micrograms of 14 polysaccharide types per dose.

Immune responses were determined to three different doses of a pneumococcal vaccine which contained 10, 25, or 50 micrograms of 14 polysaccharide types (1, 3, 4, 6A, 6B, 7F, 8, 9N, 12F, 14, 18C, 19F, 20, and 23F) per dose. Pre- and 4-weeks postvaccination sera were examined by radioimmunoassay. Ratios of geometric mean titers (GMT) showed a greater than threefold increase of antibodies to each type of polysaccharide regardless of the dose of antigen. The post-GMT was highest to 12 of 14 types in recipients of the 25-micrograms vaccine. Subjects in the group receiving a 25-micrograms dose of each antigen showed more two- and fourfold titer increases than did subjects in the group receiving 10- and 50-micrograms doses, but, in general, seroconversion rates were similar in all the groups. All GMT values in the 25-micrograms vaccine group were well above what is currently considered to be the protective level of antibody. Local reactions, overall, were low in all groups. Pain, induration, and tenderness at the site of injection, which were greatest in recipients of the 50-micrograms dose/antigen, were progressively lower with the 25- and 10-micrograms dose/antigen.