Comparison of an acellular pertussis-component diphtheria-tetanus-pertussis (DTP) vaccine with a whole-cell pertussis-component DTP vaccine in 17- to 24-month-old children, with measurement of 69-kilodalton outer membrane protein antibody

Healthy 17- to 24-month-old children, previously immunized with three doses of whole-cell diphtheria-tetanus-pertussis (DTP) vaccine, were enrolled in a multicenter double-blind, randomized study comparing a DTP vaccine with an acellular pertussis-component (APDT) and a conventional whole-cell pertussis-component DTP vaccine. Thirty-eight children received APDT vaccine, and 37 children received DTP vaccine. APDT vaccine reciplents had significantly less local pain and warmth than DTP vaccine reciplents. Antibody responses to lymphocytosis-promoting factor were similar in the two groups. The APDT vaccine recipients had a higher IgG antibody response to filamentous hemagglutinin than the DTP vaccinees had. Equivalent agglutinin responses were seen in the two groups. The APDT vaccine recipients had a significantly better antibody response to the 69-kilodalton outer membrane protein, as measured by an enzyme-linked immunosorbent assay, than DTP vaccinees had 1 month and 1 year after immunization. This APDT vaccine was immunogenic and caused fewer local reactions than conventional DTP vaccine when administered as a fourth dose to 17- to 24-month-old children.