Objectives:

• To present the rates of adverse reactions after a dose of DAPTACEL® vaccine administered to children 4 to 6 years of age who have previously received four doses of PENTACEL™ vaccine.
• To present immunogenicity before and after a single dose of DAPTACEL® vaccine administered to children 4 to 6 years of age who have previously received four doses of PENTACEL™ vaccine.

This study is designed to assess the safety and immunogenicity of DAPTACEL® vaccine administered at 4 to 6 years of age according to the US standard of care. The study population consists of PENTACEL™-primed subjects from Aventis Pasteur's pivotal studies 494-01 and 494-03. These children will receive DAPTACEL® vaccine as a 5th dose immunization between 4 to 6 years of age.

Inclusion Criteria :

• Aged ≥ 4 years and 6 years.
• Signed and dated Investigational Review Board-approved informed consent from a parent or legally authorized representative.
• Judged to be in good health on the basis of reported medical history and physical examination.
• Able and willing to attend the scheduled visits and to comply with the study procedures.
• Has documented complete infant series and 4th dose in Study 494-01 or Study 494-03, consisting of four previous administrations of PENTACEL™.

Exclusion Criteria :

• Received a 5th dose of DTaP-containing vaccine scheduled at 4 to 6 years of age.
• Serious underlying chronic disease, including, but not limited to:
• Diabetes mellitus; malignancy; cardiopulmonary disease; renal, endocrinologic, or hepatic dysfunction; or hematologic disorder; or
• Unstable or evolving neurologic disorders that may predispose the subject to seizures or neurologic deterioration.
• Known or suspected primary or acquired disease of the immune system.
• Administration of immune globulin or other blood products within the last 3 months, or injected or oral corticosteroids or other immunomodulatory therapy within 6 weeks of the study vaccine. Individuals on a tapering dose schedule of oral steroids lasting <7 days may be included in the trial as long as they have not received more than 1 course within the last 2 weeks prior to enrollment.
• Had allergy shots started or had changes in regimen or dosing of allergy shots within the last 4 weeks.
• Receipt of any other vaccine within the past 30 days, or planning to receive another vaccine within 30 days before the Visit 2 blood draw, with the exclusion of M-M-R®II and IPV.
• Any other condition which, in the opinion of the Investigator, would pose a health risk to the subject or interfere with the evaluation of the vaccine.
• Enrolled in another vaccine trial.
• Personal history of physician-diagnosed or laboratory-confirmed pertussis disease within the past 30 months.
• Known or suspected allergy to any of the vaccines or vaccine components intended for use in this study.

Temporary contraindications:

• A subject who meets either of the following criteria at the time of planned vaccination will have enrollment deferred until complete resolution of symptoms:

Oral temperature ≥ 100.4°F (≥ 38.0ºC) (Note: A tympanic thermometer should not be used).

• Any moderate or severe acute illness with or without fever.