Immunogenicity and Safety of an Investigational Quadrivalent Meningococcal Conjugate Vaccine in Toddlers

The purpose of the study was to evaluate the immunogenicity and describe the safety of a single dose of Meningococcal Polysaccharide (Serogroups A, C, Y and W) Tetanus Toxoid (MenACYW) Conjugate vaccine compared to the licensed Meningococcal polysaccharide groups A, C, W-135 and Y (Nimenrix®) Conjugate vaccine in toddlers 12 to 23 months of age in the European Union (EU). The toddlers were either meningococcal vaccine naïve or had received monovalent meningococcal C (MenC) vaccination during infancy to evaluate any potential impact of the meningococcal vaccine background on the immunogenicity and safety profile of the investigational product. Primary Objectives: * To demonstrate the non-inferiority of the antibody response to meningococcal serogroups A, C, Y, and W after a single dose of MenACYW Conjugate vaccine or Nimenrix® in toddlers who either were meningococcal vaccine naïve or had received monovalent MenC vaccination during infancy. * To demonstrate the non-inferiority of the antibody response to meningococcal serogroups A, C, Y, and W after a single dose of MenACYW Conjugate vaccine or Nimenrix® in meningococcal vaccine naïve toddlers. Secondary Objectives: * To compare the antibody responses (geometric mean titers \[GMTs\]) to meningococcal serogroups A, C, Y, and W after a dose of MenACYW Conjugate vaccine or Nimenrix® as measured by serum bactericidal assay using human complement (hSBA) in toddlers who either were meningococcal vaccine naïve or had received monovalent MenC vaccination during infancy. * To compare the antibody responses (GMTs) to meningococcal serogroups A, C, Y, and W after a dose of MenACYW Conjugate vaccine or Nimenrix® as measured by hSBA in meningococcal vaccine naïve toddlers. * To compare the antibody responses (GMTs) to meningococcal serogroups A, C, Y, and W after a dose of MenACYW Conjugate vaccine or Nimenrix® as measured by hSBA in toddlers who received monovalent MenC vaccination during infancy.