This study is designed to assess the immunogenicity and safety of tetanus toxoid, reduced diphtheria toxoid and acellular pertussis vaccine (ADACEL®, Tdap vaccine) as a booster dose in adolescents in Japan.

Primary Objective:

• To assess the immunogenicity of Tdap (SP306) when administered as a single dose in Japanese adolescents

Secondary Objective:

• To assess the safety of Tdap vaccine when administered as a single dose in Japanese adolescents.

All participants will receive a single booster dose of Tdap vaccine (ADACEL®) on Day 0 and undergo immunogenicity assessment from blood samples provided prior to, and 28 days post-vaccination. Tolerability and safety will be monitored up to 28 days post-vaccination.

Inclusion Criteria:

• Aged 11 or 12 years on the day of inclusion
• Informed consent form and assent form signed and dated by the parent(s) / legal representative and the subject respectively
• Completed childhood vaccination against diphtheria, pertussis and tetanus (i.e, received 4 doses of Japanese-produced tetanus toxoid, diphtheria toxoid and acellular pertussis vaccine absorbed [DTaP vaccine]), confirmed by checking immunization records and have not yet undergone additional adsorbed Diphtheria and Tetanus toxoid (DT) vaccination
• Able to attend all scheduled visits and to comply with all trial procedures
• For female subjects, either pre-menarchal, or post-menarchal with a negative urine pregnancy test.

Exclusion Criteria:

• Any conditions or diseases which, in the opinion of the investigator
• would pose a health risk to the subject
• or might interfere with the ability to participate fully in the study
• or might interfere with evaluation of the vaccine
• or would otherwise make participation inappropriate according to the investigator's clinical judgment
• History of diphtheria, tetanus, pertussis, confirmed either clinically, serologically, or microbiologically
• Known systemic hypersensitivity to any of the vaccine components or history of a life threatening reaction to a vaccine containing the same substances of the study vaccine
• Vaccination in the last 5 years against tetanus, diphtheria, and/or pertussis
• Known or suspected congenital immunodeficiency, or current / previous acquired immunodeficiency, or current / previous receipt of immunosuppressive therapy such as anti-cancer chemotherapy or radiation therapy, or current / previous (within the last 6 months) systemic corticosteroid therapy
• Participation in another clinical trial investigating a vaccine, drug, medical device, or medical procedure in the 4 weeks preceding the trial inclusion
• Planned participation in another clinical trial during the present trial period
• Receipt of blood or blood-derived products in the past 3 months, that might interfere with assessment of the immune response
• Receipt of any vaccine within the 4 weeks preceding the trial vaccination, except for influenza vaccination, which may be received at least 2 weeks before the study vaccine
• Planned receipt of any vaccine during the trial period
• Clinical or known serological evidence of systemic illness including Hepatitis B, Hepatitis C and/or Human Immunodeficiency Virus (HIV) infection
• At high risk for diphtheria, tetanus or pertussis infection during the trial
• Known pregnancy, or a positive urine pregnancy test
• Currently breastfeeding a child
• Known thrombocytopenia, contraindicating intramuscular (IM) vaccination, or a history of thrombocytopenia
• Bleeding disorder, or receipt of anticoagulants in the 3 weeks preceding inclusion, contraindicating IM vaccination
• History of acute disseminated encephalomyelitis, encephalopathy, Guillain-Barré Syndrome (GBS), or autoimmune disease
• Deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized involuntarily
• Current alcohol abuse or drug addiction that might interfere with the ability to comply with trial procedures
• Identified as an employee of an Investigator, a study center, a study-affiliated vendor, or the Sponsor, with direct or indirect involvement in the proposed study or other studies under the direction of that Investigator or study center; or identified as a spouse or child (whether natural or adopted) of such an employee.