The aim of the study is to further characterize the safety and immunogenicity of Menactra® in the population <2 years of age when administered alone and when the second dose is administered concomitantly with the 4th dose of Pentacel®, a licensed pediatric vaccine.

Primary Objectives:

• To evaluate and compare the antibody responses to meningococcal serogroups A, C, Y, and W-135 induced by 2 injections of Menactra® in subjects aged 9 months at the first vaccination visit and 15 to 18 months at the second vaccination visit.
• To evaluate and compare the antibody responses to Pertussis (pertussis toxoid [PT], filamentous haemagglutinin [FHA] and pertactin [PRN]) antigens induced by a dose of Pentacel® when administered concomitantly with Menactra® to those elicited by a dose of Pentacel® administered alone.
• To evaluate and compare the antibody responses to polyribosylribitol phosphate (PRP), tetanus and diphtheria antigens induced by a dose of Pentacel® when administered concomitantly with Menactra® to those elicited by a dose of Pentacel® alone.

Observational Objectives:

• To describe the safety profile (immediate unsolicited AEs within 30 minutes of each trial vaccination, solicited reactions within 7 days of each vaccination, unsolicited AEs within 30 days of each vaccination, and serious adverse events [SAEs] throughout the course of the trial from Day 0 up to Day 30 after the last trial vaccination[s]) in all trial groups
• To describe the antibody responses to meningococcal serogroups A, C, Y, and W-135, measured by SBA HC, 30 days after the second Menactra® administration
• To describe the antibody responses to Pentacel® (PT, FHA, PRN, FIM, diphtheria, tetanus, polio, PRP) measured by enzyme-linked immunosorbent assay (ELISA), radioimmunoassay (RIA), or functional assays.

Participants will be vaccinated according to their randomized groups at age 9 months and at age 15 to 18 months. They will undergo immunogenicity assessment and safety monitoring post-vaccination.

Inclusion Criteria:

• Aged 9 months (249 to 305 days) for Groups 1 and 2, or 15 to 18 months (420 to 570 days) for Group 3 on the day of the first trial visit
• Informed consent form has been signed and dated by the parent(s) or other legally acceptable representative
• Received 3 doses of any DTaP-containing vaccines
• Received 3 doses of a Hib-containing vaccine, or 2 doses if the subject received PRP-OMP (PedvaxHIB® or Comvax®[HepB-Hib])
• Received at least 3 doses of a CRM197-based pneumococcal conjugate vaccine (Pneumococcal conjugate vaccine [PCV] or 13-Valent pneumococcal conjugate vaccine [PCV13])
• Subject and parent/ legally acceptable representative are able to attend all scheduled visits and to comply with all trial procedures.

Exclusion Criteria:

• Participation in the 4 weeks preceding the first trial vaccination or planned participation during the present trial period in another clinical trial investigating a vaccine, drug, medical device, or medical procedure
• Receipt of any vaccine in the 4 weeks preceding each trial vaccination or planned receipt of any vaccine in the 4 weeks following each trial vaccination, except for influenza vaccination, which may be received at least 2 weeks before or after the trial vaccination(s)
• Vaccination against meningococcal disease with either the trial vaccine or another vaccine, or receipt of the 4th dose of any DTaP-containing vaccines, receipt of the 4th dose of a Hib-containing vaccine, or receipt of the 3rd dose of PRP-OMP (PedvaxHIB® or Comvax® [Hep B-Hib]) prior to enrollment or during the conduction of the trial, except for Group 1 subjects, who may receive Hib vaccine at 12 months
• Receipt of immune globulins, blood or blood-derived products in the past 3 months
• Known or suspected congenital or acquired immunodeficiency; or receipt of immunosuppressive therapy, such as anti-cancer chemotherapy or radiation therapy, within the preceding 6 months; or long-term systemic corticosteroid therapy (prednisone or equivalent for more than 2 consecutive weeks within the past 3 months). Topical steroids are not included in this exclusion criterion
• History of invasive meningococcal infection, confirmed either clinically, serologically, or microbiologically
• Personal history of Guillain-Barré Syndrome
• History of encephalopathy (e.g., coma, decreased level of consciousness, prolonged seizures) within 7 days of a previous dose of a pertussis containing vaccine that is not attributable to another identifiable cause
• Known systemic hypersensitivity to any of the vaccine components, or history of a life-threatening reaction to one of the vaccines used in the trial or to a vaccine containing any of the same substances
• Known thrombocytopenia, as reported by the parent/ legally acceptable representative, contraindicating intramuscular vaccination
• Bleeding disorder, or receipt of anticoagulants in the 3 weeks preceding inclusion, contraindicating intramuscular vaccination
• In an emergency setting or hospitalized involuntarily
• Chronic illness that, in the opinion of the investigator, is at a stage where it might interfere with trial conduct or completion
• Moderate or severe acute illness/ infection (according to investigator judgment) or febrile illness (temperature ≥ 100.4°F [≥ 38.0°C]) on the day of vaccination. A prospective subject should not be included in the trial until the condition has resolved or the febrile event has subsided
• Receipt of oral or injectable antibiotic therapy within 72 hours prior to any trial blood draw (topical antibiotics, drops, or ointments are not included in this criterion)
• Identified as a natural or adopted child of the Investigator or employee with direct involvement in the proposed trial.