Immune Response and Safety Comparison of 3 Lots of GSK Biologicals' DTaP-IPV Candidate Vaccine to DTaP + IPV Vaccines

The aims of this trial are to demonstrate the consistency of three manufacturing lots of GSK Biologicals' DTaP-IPV candidate vaccine in terms of immunogenicity and to evaluate the non-inferiority of GSK Biologicals' DTaP-IPV vaccine with respect to immunogenicity and safety compared to the control vaccines (separate injections of GSK Biologicals' DTaP vaccine \[Infanrix\] and Aventis Pasteur's IPV vaccine \[IPOL\]) when administered as a 5th dose of DTaP and a 4th dose of inactivated poliovirus vaccine in subjects 4 to 6 years of age. Vaccines will be co-administered with the second dose of M-M-RII, which is recommended at this age. Concomitant administration of a US-licensed influenza vaccine will be allowed according to seasonal availability of vaccine and at the discretion of the investigator.

* Investigational groups: 3, each receive one of 3 lots of DTaP-IPV vaccine.
* Control: US-licensed DTaP (Infanrix) + US-licensed IPV (IPOL) vaccines administered in separate injections.
* Two study visits one month apart for a subset of subjects (Safety and Immunogenicity subset) with a blood draw at each visit. All other subjects will have one visit.
* A telephone contact 4-6 days after vaccination for all subjects, a telephone contact 31-38 days after vaccination for the Safety only subset and a telephone contact for all subjects during the extended safety follow-up phase (5 months following the active phase).

Eligibility Criteria:
Inclusion criteria:

* Male or female child between and including 4 and 6 years of age at the time of vaccination.
* Free of obvious health problems as established by medical history and brief medical evaluation before entering into the study.
* Received 4 doses of Infanrix and 3 doses of IPOL during the first 2 years of life.
* Vaccination against measles, mumps, and rubella in the second year of life.
* Subjects whom the investigator believed would comply with the requirements of the protocol.
* Written informed consent obtained before study entry from the parent(s) or guardian(s) of the subject.

Exclusion criteria:

* Use of any investigational or non-registered drug or vaccine other than the study vaccines within 30 days preceding the administration of study vaccines, or planned use during the study period.
* History of previous or intercurrent diphtheria, tetanus, pertussis, polio, measles, mumps, or rubella disease, or of vaccination against these diseases given after the second year of life.
* Known exposure to diphtheria, tetanus, pertussis, or polio, prior to vaccination.
* Poliovirus vaccination with one or more doses of OPV vaccine.
* Administration or planned administration of a vaccine not foreseen by the study protocol within 30 days of study vaccination and ending at Day 30.
* Chronic administration or administration of immunosuppressants or other immune modifying drugs within six months prior to study vaccination or planned administration during the study period ending at Day 30.
* Administration of immunoglobulins and/or any blood products within three months prior to study vaccination or planned administration during the study period ending at Day 30.
* Any confirmed or suspected immunosuppressive or immunodeficient condition, including human immunodeficiency virus infection.
* History of seizures or progressive neurological disorder, including infantile spasms, uncontrolled epilepsy or progressive encephalopathy.
* Major congenital defects or serious chronic illness.
* Acute disease at the time of enrollment.
* History of allergic disease or reactions likely to be exacerbated by any component of the vaccine(s), including allergic reactions to 2-phenoxyethanol, formaldehyde, neomycin, polymyxin B, streptomycin, gelatin, and/or latex.
* History of anaphylactic reaction to egg proteins or previous doses of the vaccine(s).
* Encephalopathy within 7 days of administration of previous dose of Infanrix.
* Fever ≥ 40.5°C or 104.9°F (rectal temperature) (39.5°C or 103.1°F, oral/axillary) within 48 hours of previous dose of Infanrix not due to another identifiable cause.
* Collapse or shock-like state (hypotonic-hyporesponsive episode) within 48 hours of previous dose of Infanrix.
* Persistent, severe, inconsolable screaming or crying lasting ≥ 3 hours which occurred within 48 hours of administration of previous dose of Infanrix.
* Thrombocytopenia following a previous dose of M-M-RII or its component vaccines.
* Inability to contact a parent/guardian of the subject by telephone.
* Blood dyscrasias (including current thrombocytopenia), leukemia, lymphomas or other malignant neoplasms affecting the bone marrow or lymphatic systems.
* Family history of congenital or hereditary immunodeficiency, unless the immune competence of the subject was demonstrated.