A randomised, double-blind, non-inferiority clinical trial on the safety and immunogenicity of a tetanus, diphtheria and monocomponent acellular pertussis (TdaP) vaccine in comparison to a tetanus and diphtheria (Td) vaccine when given as booster vaccinat

► Monocomponent aP vaccine was highly immunogenic given as TdaP booster vaccination to adults. ► TdaP was non-inferior to Td in eliciting seroprotection against tetanus and diphtheria. ► TdaP was safe and rates of injection site reactions were low and comparable to rates after Td.