Safety and Immunogenicity of 2 Doses Versus 1 Dose of Acellular Pertussis Vaccines Containing Genetically-detoxified Pertussis Toxin in Young Adults Previously Primed With Acellular Pertussis Vaccines

Inclusion Criteria:

• Has provided written informed consent;
• Male or female, ages 18 to 30 years (inclusive) at the time of enrollment;
• With documented history of acellular pertussis immunization (5 doses);
• Free of clinically significant health problems, as determined by pertinent medicalhistory and clinical examination at study screening;
• Non-pregnant, non-lactating females :
• Able to attend all scheduled visits during one year and to understand and comply withthe study procedures;

Exclusion Criteria:

• Prior dTpa immunization within the last 5 years or prior dT immunization within thelast 2 years, or any other investigational vaccine likely to impact on interpretationof the trial data
• Suspected or confirmed pertussis infection within the last 10 years or documentedpertussis infection in a household member within the last 10 years;
• History of severe local or systemic reactions to any vaccination;
• Known hypersensitivity or allergy to diphtheria, tetanus, or pertussis-containingvaccines (including excipients);
• Receipt of investigational product up to 30 days prior to enrollment or ongoingparticipation in another interventional clinical trial;
• Receipt of licensed vaccines within 30 days of planned study immunization or ongoingparticipation in another clinical interventional trial likely to interfere with studyresults;
• Acute or chronic, clinically significant psychiatric, hematologic, pulmonary,cardiovascular, or hepatic or renal functional abnormality as determined by theInvestigator based on medical history and physical exam;
• Any confirmed or suspected immunosuppressive or immunodeficient condition, includinghuman immunodeficiency virus (HIV) infection, asplenia, cytotoxic therapy in theprevious 5 years, and/or diabetes;
• Has a known history of vaccine-induced Guillain-Barré Syndrome;
• Has an active malignancy or recent (<10 years) history of metastatic or hematologicmalignancy;
• Suspected or known alcohol and/or illicit drug abuse within the past 5 years;
• Pregnant or lactating female, or female intending to becoming pregnant during thestudy period;
• Administration of immunoglobulins within the 120 days preceding study entry or plannedadministration during the study period;
• History of blood donation (at least 450 ml) within 30 days of enrollment or plans todonate within the 30 days following and preceding each blood draw;
• Receipt of chronic (>14 days) immunosuppressants or other immune-modifying drugswithin 6 months of study entry:
• Any other significant finding that, in the opinion of the investigator, would increasethe risk of the individual's having an adverse outcome by participating in this study.