Purpose: This study was conducted to assess the immunogenicity and safety of a tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine containing three pertussis antigens (Boostrix, Tdap3v), currently licensed in the US for use in adolescents 10-18 years of age, in adults 19-64 years of age.
Methods: 2284 healthy adults, aged 19-64 years, were randomized to receive a single dose of Tdap vaccine, either Tdap3v or a five-pertussis component Tdap vaccine (Adacel, Tdap5v) licensed for adult use in the US. Blood samples were taken before and 1 month after vaccination. Reactogenicity was assessed for 15 days after vaccination.
Results: Tdap3v was comparable to Tdap5v in eliciting seroprotective levels of antibodies to diphtheria and tetanus toxoids, with >98% of subjects having post-vaccination seroprotective antibody levels (> or =0.1 IU/mL) against diphtheria or tetanus toxoids. The pertussis components of Tdap3v were shown to be immunogenic in adults, with booster responses to pertussis toxoid (PT), filamentous hemagglutinin (FHA), and pertactin (PRN) observed in 77.2%, 96.9%, and 93.2%, respectively, of Tdap3v recipients, and in 47.1%, 94.0%, and 91.7%, respectively, of Tdap5v recipients. Anti-pertussis antibody GMCs in Tdap3v recipients exceeded those observed in infants following primary DTaP vaccination, in whom efficacy against pertussis disease was subsequently demonstrated. Injection site reactions (pain, redness, and swelling) and fever > or =37.5 degrees C (99.5 degrees F) were reported significantly more often (p<0.05) by Tdap5v recipients than by Tdap3v recipients. Fatigue preventing normal daily activities was reported by a small but significantly greater percentage of Tdap3v recipients (2.5%) than Tdap5v recipients (1.2%, p<0.05).
Conclusion: In adult recipients, Tdap3v was comparable to an approved Tdap vaccine in providing seroprotection against diphtheria and tetanus, and produced immune responses to pertussis antigens consistent with protection against disease. The overall safety profile of Tdap3v was generally comparable to that of Tdap5v [NCT #106316].
Trial registration: ClinicalTrials.gov NCT00346073.