Exploratory Trial to Evaluate the Safety and Immunogenicity of Menactra® and Menomune® Vaccines in Subjects ≥ 56 Years

Inclusion Criteria: * Ambulatory and healthy, as determined by medical history. * 56 years of age or older at the time of vaccination. * Signed Institutional Review Board (IRB)-approved informed consent form. * Able to attend all scheduled visits and to comply with all trial procedures. * For a woman, inability to become pregnant or a negative urine pregnancy test at the time of enrollment. Exclusion Criteria: * Any condition which, in the opinion of the Investigator, would pose a health risk to the participant or interfere with the evaluation of the vaccine. * Serious chronic disease (i.e., cardiac, renal, neurologic, metabolic, rheumatologic, psychiatric, etc) that is unstable or that might 1) interfere with the ability to participate fully in the study or 2) interfere with evaluation of the vaccines. * Known or suspected impairment of immunologic function. * Febrile illness within the last 72 hours or an oral temperature ≥ 100.4ºF at the time of inclusion. * History of documented invasive meningococcal disease or previous meningococcal vaccination. * Known or suspected receipt of a diphtheria-containing vaccine within the preceding 2 years. * Administration of immune globulin or other blood products within the last three months, or injected or oral corticosteroids or other immunomodulator therapy within six weeks of the study vaccine. Individuals on a tapering dose schedule of oral steroids lasting \< 7 days may be included in the trial as long as they have not received more than one course within the last two weeks prior to enrollment. * Systemic antibiotic therapy within the 72 hours prior to collection of any blood samples. * Received any vaccine in the 28-day period prior to enrollment or scheduled to receive any vaccination through Visit 2 for Groups 1 and 2 and through Visit 3 for Groups 3 and 4. Influenza vaccines may be received 2 weeks before or after a study vaccination. * Suspected or known hypersensitivity to latex or to any of the components of either Menactra® vaccine or Menomune® vaccine. * Previous personal history of Guillain-Barré syndrome. * Not available for the entire study period or unable to attend the scheduled visits or to comply with the study procedures. * In females of childbearing potential, a positive or equivocal urine pregnancy test at enrollment. * A nursing mother. * Participation in another interventional clinical trial in the 4 weeks preceding enrollment or planning to participate in another interventional clinical trial during the planned period of this study. * Current use of alcohol or recreational drugs that may interfere with the subject's ability to comply with trial visits or procedures. * Thrombocytopenia or bleeding disorder contraindicating intramuscular vaccination. * Subject deprived of freedom by an administrative or court order, or in an emergency setting, or hospitalized without his/her consent.