Immuno,Safety of GSK Vaccine 134612 Given at Age of 12-15 Months 15-18 Months Post-priming With GSK Vaccine 792014

The purpose of the study is to characterize the immunogenicity \& safety of a booster dose of GSK Biologicals' meningococcal vaccine 134612 given at 12-15 months of age or at 15-18 months of age (co-administered with Infanrix®) in healthy toddlers primed with GSK Biological's Hib-meningococcal vaccine 792014. This study is single-blinded for the primary phase and open-label for the booster phase.

The purpose of this study is to evaluate the titer of antibody for serogroups A, C, Y and W-135 and the safety of a booster dose of GSK Biologicals' meningococcal vaccine 134612 given to toddlers who were primed with GSK Biological's Hib-meningococcal vaccine 792014. In addition, this study will provide immunogenicity and safety data on the co-administration of Infanrix with meningococcal vaccine 134612 as compared to Infanrix administered alone.

Depending on the group the subject is assigned to, one or two blood samples will be taken out of the subject's arm during the study.

The protocol posting has been updated following a protocol amendment.

Eligibility Criteria:
Inclusion Criteria:

* Subjects for whom the investigator believes that parents/guardians can and will comply with the requirements of the protocol.
* A male or female between, and including, 6 and 12 weeks of age (+ 6 days) at the time of the first vaccination.
* Written informed consent obtained from the parent or guardian of the subject.
* Healthy subjects as established by medical history and clinical examination before entering into the study.
* Born after 36 weeks gestation.
* For inclusion in the booster phase, subjects must have received all three doses in the primary phase.

Exclusion Criteria:

Exclusion criteria for enrolment (primary phase)

* Use of any investigational or non-registered product (drug or vaccine) other than the study vaccine(s) within 30 days preceding the first dose of study vaccine, or planned use during the study period.
* Chronic administration (defined as more than 14 days) of immunosuppressants or other immune-modifying drugs since birth.
* Planned administration/ administration of a vaccine not foreseen by the study protocol within 30 days of the first dose of study vaccine(s).
* Previous vaccination against Neisseria meningitidis, Haemophilus influenzae type b, diphtheria, tetanus, pertussis, and/or poliovirus; more than one previous dose of hepatitis B vaccine.
* History of Neisseria meningitidis, hepatitis B, Haemophilus influenzae type b, diphtheria, tetanus, polio or pertussis diseases.
* Any confirmed or suspected immunosuppressive or immunodeficient condition based on medical history and physical examination
* History of allergic disease or reactions likely to be exacerbated by any component of the vaccines, or by dry natural latex rubber.
* Major congenital defects or serious chronic illness.
* History of any neurologic disorders or seizures.
* Acute disease at time of enrollment.
* Administration of immunoglobulins and/or any blood products since birth or planned administration during the study period.
* Concurrent participation in another clinical study, at any time during the study period, in which the subject has been or will be exposed to an investigational or a non-investigational product (pharmaceutical product or device).

Exclusion criteria for enrolment (booster phase)

* Use of any investigational or non-registered product (drug or vaccine) other than the study vaccine(s) within 30 days preceding entry into the booster phase (Visit 4), or planned use during the study period.
* Chronic administration (defined as more than 14 days) of immunosuppressants or other immune-modifying drugs since birth.
* Planned administration/administration of a vaccine not foreseen by the study protocol within 30 days of entry into the booster phase (Visit 4) with the exception of Prevnar® and Hib (see the following three criteria) (Note; licensed influenza vaccine is allowed throughout the study)
* Planned administration/administration of a fourth dose of Prevnar® within 30 days of a booster dose of Infanrix®
* Previous administration of a booster dose of Hib prior to entry to the booster phase.
* Previous administration of a primary dose of Hib vaccine that is not part of the study protocol.
* Previous vaccination against Neisseria meningitidis that is not part of the study protocol.
* Previous vaccination with diphtheria, tetanus and pertussis antigens outside of the primary phase of the study.
* History of Neisseria meningitidis, Hib, diphtheria, tetanus or pertussis diseases.
* Any confirmed or suspected immunosuppressive or immunodeficient condition based on medical history and physical examination.
* History of allergic disease or reactions likely to be exacerbated by any component of the vaccines, or by dry natural latex rubber.
* Major congenital defects or serious chronic illness.
* History of any neurologic disorders or seizures.
* Acute disease at time of enrollment.
* Administration of immunoglobulins and/or any blood products within the past 3 months or planned administration during the study period.
* Concurrent participation in another clinical study, at any time during the study period, in which the subject has been or will be exposed to an investigational or a non-investigational product (pharmaceutical product or device).