Co-administration of Meningococcal Vaccine GSK134612 and Pneumococcal Vaccine GSK1024850A vs Individual Administration

The purpose of this study is to demonstrate, in 12-23 months old subjects, the non-inferiority of meningococcal vaccine GSK134612 and pneumococcal vaccine GSK1024850A when co-administered, compared to each vaccine administered individually.

Multi-center study with 3 parallel groups. One group will receive 2 vaccines injections at the same visit (pneumococcal+ meningococcal), one group will receive a pneumococcal vaccine followed one month later by a meningococcal vaccine, and the last group will receive the meningococcal vaccine followed one month later by the pneumococcal vaccine.

All subjects will have one blood sample taken before vaccination and one blood sample taken one month after each vaccination (i.e. the first group will have 2 blood samples taken, and the other two groups will have 3 blood sample taken)

Eligibility Criteria:
Inclusion Criteria:

* Subjects who the investigator believes that their parents/guardians can and will comply with the requirements of the protocol.
* A male or female between, and including, 12 and 23 months of age at the time of the first booster vaccination, who previously participated in study 109661 conducted in Mexico or in study 109861 conducted in Taiwan and who received 3 doses of the GSK1024850A vaccine.
* 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.

Exclusion Criteria:

* Use of any investigational or non-registered product (drug or vaccine) other than the study vaccines within 30 days preceding the first dose of study vaccine(s), or planned use during the study period.
* Chronic administration (defined as more than 14 days) of immunosuppressants or other immune-modifying drugs within six months prior to the first vaccine dose.
* Planned administration/ administration of a vaccine not foreseen by the study protocol within 30 days before the first dose of vaccine(s) and 30 days after the last dose of vaccine(s).
* Concurrently participating 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).
* Previous vaccination with a meningococcal vaccine.
* Previous administration of a fourth dose of a pneumococcal vaccine
* Previous vaccination with tetanus toxoid within the last month (including also tetanus toxoid given as part of Hib-TT conjugate vaccine).
* History of meningococcal or pneumococcal invasive disease.
* History of reactions or allergic disease likely to be exacerbated by any component of the vaccines.
* Hypersensitivity reaction due to previous vaccination with GSK1024850A vaccine.
* History of seizures (this criterion does not apply to subjects who have had a single, uncomplicated febrile convulsion in the past) or progressive neurological disease.
* Any confirmed or suspected immunosuppressive or immunodeficient condition, including human immunodeficiency virus (HIV) infection, based on medical history and physical examination (no laboratory testing required).
* A family history of congenital or hereditary immunodeficiency, unless the child has previously been documented, through laboratory testing, to have normal immune function.
* Major congenital defects or serious chronic illness.
* Acute disease at the time of enrolment.
* Administration of immunoglobulins and/or any blood products within the three months preceding the first dose of study vaccine or planned administration during the study period.