[Effect on anti-pertussis antibodies of reducing the amount of Japanese Diphteria-Pertussis-Tetanus vaccine among adults].

The wide spread use of Diphteria-Pertussis-Tetanus (DPT) vaccination has made pertussis rare among infants, but reports have noted the rise in adult pertussis in the United States and in Japan. Adult pertussis vaccination in the US has been approved and is becoming widely disseminated, but not in Japan, where only way to prevent adult pertussis is vaccination using infantile DPT vaccine. Reducing the Japanese DPT vaccine dose to 0.2 mL in the hope of minimizing adverse events, we studied its efficacy and safety. We nearly equalized diphteria and tetanus antigenic titers to a 0.1 mL dose of diphteria-tetanus bivalent vaccine--the booster dose regularly used in Japan--containing anti-FHA antibody titers similar to effective pertussis vaccines approved in the US. Subjects were 30 healthy volunteers who gave oral and written consent, testing anti-PT and anti-FHA antibody titers 4 weeks after vaccination. Of the 30, 29 showed a titer increase. Anti-tetanus toxoid titers tested showed increased titers in 28 subjects, the remaining 2 assumed to not have undergone previous tetanus vaccination. The incidence of local adverse effects was higher in adults than in children, but none were serious. A Japanese DPT vaccine dose of 0.2 mL thus proved effective against pertussis in adults.