Immune responses in adults to revaccination with a tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine 10 years after a previous dose

► We assessed the safety and immunogenicity of Tdap 10 years after a previous dose. ► Antibody levels to all components of Tdap had decreased 10 years after a prior dose. ► A vigorous antibody response was shown in persons previously immunized with Tdap. ► Adverse events after a first or second dose of Tdap did not differ substantially.