The purpose of this study is to evaluate the safety, reactogenicity, immunogenicity and persistence up to three years after administration of one dose of the MenACWY conjugate vaccine when given to young adults aged 18-25 years.

Administration of the candidate vaccine or of the active control (Mencevax™ ACWY) will be done in an open manner. The study consists of a vaccination phase during which subjects receive one vaccine dose (GSK's MenACWY conjugate vaccine or Mencevax™ ACWY vaccine) and 3 years of follow-up. There are in total 7 visits to the doctor: before and 2, 7 and 30 days after vaccination (vaccination phase) as well as 12, 24 and 36 months after vaccination (follow-up phase). 7 blood samples are taken: one at each visit.

Inclusion criteria:

• Healthy male or female between, and including, 18 and 25 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.
• 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.
• History of chronic alcohol consumption and/or drug abuse

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