Immunogenicity and Safety Study of 1 and 2 Doses of GlaxoSmithKline (GSK) Biologicals' Meningococcal Vaccine MenACWY-TT (GSK134612) in Toddlers, Persistence up to 5 Years After Vaccination and Co-administration With Pfizer's Prevenar 13™Vaccine

The purpose of this study is to compare the immediate and long term (up to 5 years) immunogenicity and safety of GSK Biologicals' MenACWY-TT vaccine when given as a single dose or as 2 doses to toddlers aged 12 to 14 months. Also, this study will also assess if co-administration of GSK Biologicals' MenACWY-TT with the booster dose of Pfizer's Prevenar 13 adversely impacts the immunogenicity of either of the vaccines.

The Medicines Control Council (MCC) authorities requested that subjects be screened for HIV testing prior to study enrolment in South Africa to ensure that only HIV negative participants are enrolled. As such, HIV rapid test was added at Visit 1 only for subjects in South Africa. Subjects previously screened HIV positive will be excluded.

Eligibility Criteria:
Inclusion Criteria:

* Subjects' parent(s)/Legally Acceptable Representative(s) \[LAR(s)\] who, in the opinion of the investigator, can and will comply with the requirements of the protocol.
* A male or female between, and including, 12 and 14 months of age at the time of the first vaccination.
* Written informed consent obtained from the parent(s)/LAR(s) of the subject.
* Healthy subjects as established by medical history and clinical examination before entering into the study.
* Vaccination records showing the completion of the full primary vaccination schedule with Prevenar 13 and Diphtheria, Tetanus and Pertussis (DTP) containing vaccine according to local recommendations at least 5 months before the study entry.

Exclusion Criteria:

* Child in care.
* 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 or planned use during the study period.
* Chronic administration (defined as more than 14 days in total) of immunosuppressants or other immune-modifying drugs within six months prior to the first vaccine dose. For corticosteroids, this will mean prednisone 0.5 mg/kg/day, or equivalent. Inhaled and topical steroids are allowed.
* Planned administration/administration of a vaccine not foreseen by the study protocol within the period starting 30 days before and ending 30 days after the dose of vaccines, with the exception of a licensed inactivated influenza vaccine. Measles, Mumps Rubella (MMR) vaccine or Measles Mumps Rubella and Varicella (MMRV) vaccine can be co-administered with MenACWY-TT and/or Prevenar 13. A DTPa containing vaccine can be administered after the last blood sampling (at Visit 2 or 4 depending on the group).
* 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 vaccine/product (pharmaceutical product or device).
* Previous vaccination against Neisseria meningitidis.
* Previous booster vaccination against Streptococcus pneumoniae.
* Previous booster vaccination against Corynebacterium diphtheriae, Clostridium tetani and Bordetella pertussis.
* History of meningococcal disease.
* Any confirmed or suspected immunosuppressive or immunodeficient condition (congenital or secondary), including human immunodeficiency virus (HIV) infection, based on medical history and physical examination (no laboratory testing required)\*

  * Note: With the exception of HIV rapid testing which will be done for subjects in South Africa.
* Family history of congenital or hereditary immunodeficiency.
* History of any reaction or hypersensitivity, including to diphtheria toxoid, likely to be exacerbated by any component of the vaccines.
* Major congenital defects or serious chronic illness.
* History of any neurological disorders or seizures, including Guillain-Barré syndrome (GBS). History of a simple, single febrile seizure is permitted.
* Acute disease and/or fever at the time of enrollment.
* Administration of immunoglobulins and/or any blood products within the 3 months preceding the first dose of study vaccine or planned administration during the study period.