A randomized clinical trial of acellular pertussis vaccines in healthy adults: Dose-response comparisons of 5 vaccines and implications for booster

The safety and immunogenicity of 5 acellular pertussis vaccines (ACVs) were compared in a multicenter, randomized, double-blind trial. A total of 481 healthy adults were given a single intramuscular booster dose of ACV or pla cebo. Three different dose levels were tested for 4 ACVs: full strength (th e dose level proposed for infant immunization), one-third strength, and one -tenth strength, For 1 multicomponent vaccine, only the pertussis toroid do se level varied. Minor injection site reactions were common and similar in frequency among vaccinated groups. Late-onset injection site reactions were seen in all ACV groups. Dose-related increases in mean antibody titers aga inst vaccine antigens were seen after immunization with all ACVs, Antibody responses against antigens not known to be present in the vaccines were det ected after immunization with 4/5 ACVs, Antibody levels fell significantly during the year after immunization. These data support evaluation of ACVs f or broader use among adolescents and adults.