Pneumococcal vaccine in normal children. Primary and secondary vaccination.

A pneumococcal polysaccharide vaccine containing 50 micrograms of each of 14 pneumococcal types was administered to 79 children 2 to 5 years of age. In earlier studies, 52 of these children had received pneumococcal vaccine; 27 had received a placebo. Local reactions were significantly greater in the reimmunized group. Antibody response to the vaccine was similar in both groups. Mean fold rises to most vaccine components were at least twofold. The response to specific pneumococcal types was unrelated to the frequency with which each type causes illness. Response to type 6 continued to be poor for children up to age 5 years. A vaccine with improved immunogenicity must be developed before widespread use in normal children is advocated. However, the 14-valent pneumococcal polysaccharide vaccine currently available is moderately immunogenic in children by age 2 years and should be given to patients with increased risk of pneumococcal illness at that time.