A comparative trial of the reactogenicity and immunogenicity of Takeda acellular pertussis vaccine combined with tetanus and diphtheria toxoids. Outcome in 3- to 8-month-old infants, 9- to 23-month-old infants and children, and 24- to 30-month-old children.

The reactogenicity and immunogenicity of the Takeda acellular pertussis vaccine combined with tetanus and diphtheria toxoids were compared in 139 infants aged 3 to 8 months, 60 infants and children aged 9 to 23 months, and 99 children aged 24 to 30 months. Good antibody responses to pertussis toxin (PT), filamentous hemagglutinin (FHA), and agglutinogens occurred in all age groups after both the third and fourth doses. After the fourth (booster) dose, the mean antibody values in initially seronegative infants vaccinated at 3 to 8 months of age were as follows: anti-PT, 67.8 enzyme-linked immunosorbent assay units (EU) per milliliter; anti-FHA, 149.5 EU/mL; the agglutinin titer was 125.6. The values in initially seronegative children vaccinated at 24 to 30 months of age were as follows: anti-PT, 92.9 EU/mL; anti-FHA, 251.7 EU/mL; the agglutinin titer was 275.8. Reactions following immunization were minimal. Except for drowsiness after the first dose in infants, there were no clinically significant differences in reactions between infants and older children. The findings in this study coupled with the recent demonstration of efficacy of this vaccine in 2-year-old children supports the recent Japanese recommendation to lower the age of immunization with acellular pertussis vaccine combined with tetanus and diphtheria toxoids to 3 months.