At least one AE occurring within 31 days after vaccination considered by the investigator to be related to vaccination was reported by 12.7% (95% CI 5.3;24.5) of participants in the dTpa-0.3 group, 11.7% (4.8;22.6) in the dTpa-0.133 group and 14.5% (6.9;25.8) in the dTpa-0.5 group. Vaccine-related AEs reported at least twice in any group were injection site induration, injection site pruritus, arthralgia and myalgia. No related AEs were reported by more than two participants in any group. No SAEs were reported during the entire study period.