Evaluation of GlaxoSmithKline Biologicals' Boostrix® Vaccine in Comparison With Decavac™ Vaccine.

Inclusion Criteria:

- Subjects who the investigator believes that can and will comply with the requirements
of the protocol should be enrolled in the study.

- Males or females 65 years of age and older at the time of study entry.

- Free of an acute aggravation of the health status as established by medical history
and medical history and clinical examination before entering into the study.

- Written informed consent from all subjects.

Exclusion Criteria:

- Administration of a diphtheria-tetanus (Td) booster within the previous 5 years.

- Administration of a Tdap vaccine at any time prior to study entry.

- History of diphtheria and/or tetanus and/or pertussis disease.

- Use of any investigational or non-registered drug or vaccine other than the study
vaccines within 30 days preceding vaccination, or planned use during the entire study
period.

- Administration of other licensed vaccines within 2 weeks (for inactivated vaccines) or
4 weeks (for live vaccines) prior to enrolment in this study, with the exception of
influenza, vaccine, which may be administered at any time up to or during the study
period, including the day of study vaccination.

- Planned administration of any vaccine not foreseen by the study protocol up to 30 days
following vaccination, with the exception of influenza, vaccine, which may be
administered at any time up to or during the study period, including the day of study
vaccination. Pneumococcal and zoster vaccines can be administered at the discretion of
the investigator when the subject comes back at Visit 2.

- Chronic administration of immunosuppressants or other immune-modifying drugs within
six months prior to vaccination or planned administration during the study period.

- Any confirmed or suspected immunosuppressive or immunodeficient condition based on
medical history and physical examination.

- History of serious allergic reaction following any other tetanus toxoid, diphtheria
toxoid or pertussis-containing vaccine or any component of the study vaccines.

- History of encephalopathy within seven days of administration of a previous booster
dose of pertussis vaccine that is not attributable to another identifiable cause.

- Progressive neurologic disorder, uncontrolled epilepsy or progressive encephalopathy:
pertussis vaccine should not be administered to individuals with these conditions
until a treatment regimen has been established and the condition has stabilized.

- Acute (active) clinically significant pulmonary, cardiovascular, hepatic or renal
functional abnormality, as determined by clinical evaluation or pre-existing
laboratory screening tests.

- Acute disease at the time of vaccination.

- Administration of immunoglobulins and/or any blood products within the three months
preceding vaccination, or planned administration during the study period.

- Any medical condition that, in the opinion of the investigator, might interfere with
the evaluations required by the study.