The purpose of this study is to evaluate the immunogenicity, safety and reactogenicity of one dose of four different formulations of the MenACWY conjugate vaccine when given to healthy subjects aged 15-19 years. The selection of the best formulation will be based on data obtained up to one month after the vaccine dose.

3 formulations of GSK's MenACWY conjugate vaccine will be administered in a double-blind manner, while the 4th one will be single-blinded. Administration of the candidate vaccine or of the active control (Mencevax™ ACWY) will be done in an open manner. Subjects will receive one vaccine dose (GSK's MenACWY conjugate vaccine or Mencevax™ ACWY vaccine), and will have 2 blood samples taken, before and one month after vaccination.

Inclusion criteria:

• Healthy male or female between, and including, 15 and 19 years of age at the time of vaccination.
• Written informed consent obtained. Subject with previously completed routine childhood vaccinations to the best of his/her knowledge or his/her parents'/guardians' knowledge.
• Female subjects should be of non-childbearing potential, or abstinent, or using an adequate contraception.

Exclusion criteria:

• Previous vaccination against OR history of OR exposure within previous 12 months to meningococcal serogroup A, C, W-135 or Y disease.
• Administration of a tetanus vaccine within 6 months before study vaccination.
• Any confirmed or suspected immunosuppressive or immunodeficient condition, including human immunodeficiency virus (HIV) infection.
• A family history of congenital or hereditary immunodeficiency.
• History of any neurologic disorders or seizures.
• Use of any investigational or non-registered product (drug or vaccine) other than the study vaccine within 30 days preceding the first dose of study vaccine, or planned use during the study period.

Patient-level data for this study will be made available through www.clinicalstudydatarequest.com following the timelines and process described on this site.