Immunogenicity and Safety of a Booster Dose of a Quadrivalent Meningococcal Conjugate Vaccine in Children

This was an open-label, multi-center study to describe the immune persistence of the priming dose and describe the immunogenicity and safety of a booster dose of Meningococcal Polysaccharide (Serogroups A, C, Y, and W) Tetanus Toxoid (MenACYW) conjugate vaccine in children in Finland who had been vaccinated 3 years earlier as toddlers with either MenACYW conjugate vaccine or Nimenrix® as part of the MET54 study (NCT03205358). The objectives were: * To describe the antibody persistence of meningococcal serogroups A, C, Y, and W before a booster dose in children who received either MenACYW conjugate vaccine or Nimenrix® 3 years earlier as toddlers. * To describe the antibody responses to meningococcal serogroups A, C, Y, and W 30 days after a booster dose of MenACYW conjugate vaccine in children who received either MenACYW conjugate vaccine or Nimenrix® 3 years earlier as toddlers. * To describe the antibody responses against tetanus toxoid 30 days after a booster dose of MenACYW conjugate vaccine in children who received either MenACYW conjugate vaccine or Nimenrix® 3 years earlier as toddlers. * To describe the safety profile of a booster dose of MenACYW conjugate vaccine in children who received either MenACYW conjugate vaccine or Nimenrix® 3 years earlier as toddlers.