The purpose of this study is to describe the safety and immunogenicity of MenACYW conjugate vaccine compared with locally-licensed meningococcal vaccines in healthy infants and toddlers in China.

Study details include:

• Study duration (including 6-month safety follow-up after the last dose): - Cohort I (Groups 1 and 2): approximately 211 or 271 days (approximately 7 or 9 months) - Cohort II (Groups 3 and 4): up to 18 months - Cohort III (Groups 5 and 6): up to 21 months - Cohort III (Group 7): approximately 16 months
• Vaccination Visits Period:
• Cohort I (Groups 1 and 2): a 2-dose vaccination at V01 (D01) and V02 (D31) or V03 (D91). Two blood samples are collected pre-vaccination (D01) and 30 days post the 2nd dose of vaccination (D61 or D121). Telephone calls (TCs) are planned on the 4th, the 9th, and the 21st day after each vaccination, and 5 TCs (1 TC/month) are planned for the 5 months post the last on-site visit for safety follow-up. For participants receiving the second vaccination with a 3-month interval: an on-site visit is planned 30 days post the 1st dose of vaccination (V02, D31) for participant diary collection.
• Cohort II (Groups 3 and 4): a 2-dose vaccination at V01 (D01) and V02 (D31) or V03 (D91). A 1-dose booster is planned for Group 3 only at 18 MoA (within the 18th month from the participant's birth date). Up to 4 blood samples will be collected. In the primary vaccination period, blood samples are collected before the first primary vaccination (D01) and 30 days post the 2nd dose of primary vaccination (D61 or D121). A blood sample will be collected from all participants at 18 MoA. A post-booster blood sample will be collected from participants in Group 3, 30 days post their booster vaccination. Telephone calls are planned on the 4th, the 9th, and the 21st day after each vaccination (including the booster dose), and 5 TCs (1 TC/month) are planned for the 5 months post the last on-site visit of the primary and the booster vaccination periods, respectively, for safety follow-up. For participants receiving the second vaccination with a 3-month interval: an on-site visit is planned 30 days post the 1st dose of vaccination (V02, D31) for participant diary collection. - Cohort III - Groups 5 and 6: a 3-dose primary vaccination at V01 (D01), V02 (D31) and V03 (D61), a 1-dose booster at 12 MoA (within the 12th months from the participant's birth date) on V05 or at 18 MoA (within the 18th months from the participant's birth date) on V06.

In total 4 blood samples are to be collected. In the primary vaccination period, blood samples are to be collected before the first primary vaccination (D01) and 30 days post the 3rd dose of primary vaccination (D91); in the booster vaccination period, blood samples are to be collected before booster vaccination at V05 (for participants receiving the booster at 12 MoA) or V06 (for participants receiving the booster at 18 MoA), and 30 days post booster vaccination (V05 + 30 days or V06 + 30 days). Telephone calls are planned on the 4th, the 9th, and the 21st day after each vaccination (including the booster dose), and 5 TCs (1 TC/month) are planned for the 5 months post the last on-site visit of the primary and the booster vaccination periods respectively for safety follow-up.

- Cohort III - Group 7: a 3-dose primary vaccination at V01 (D01), V02 (D61) and V03 (D121), a 1-dose booster at V05 at 12 MoA (within the 12th months from the participant's birth date).

In total 4 blood samples are to be collected. In the primary vaccination period, blood samples are to be collected before the first primary vaccination (D01) and 30 days post the 3rd dose of primary vaccination (D151); in the booster vaccination period, blood samples are to be collected before booster vaccination at V05 and 30 days post booster vaccination (V06). Telephone calls are planned on the 4th, the 9th, and the 21st day after each vaccination (including the booster dose), and 5 TCs (1 TC/month) are planned for the 5 months post the last on-site visit of the primary and the booster vaccination periods (ie, V04 and V06), respectively, for safety follow-up. A safety visit is planned on the 9th day after the first vaccination for the ESDR participants (the first 30 participants in this group).

Inclusion Criteria:

• For Cohort I: Aged 12 months through 23 months on the day of inclusion. For Cohort II: Aged 6 months through 11 months on the day of inclusion. For Cohort III: Aged 2 months through 5 months on the day of inclusion - Born at full term of pregnancy (≥37 weeks) or born after a gestation period of 27 through 36 weeks and medically stable as assessed by the investigator - Informed consent form has been signed and dated by the parent(s) or other LAR (and by an independent witness if required by local regulations). - Participant and parent/LAR are able to attend all scheduled visits and to comply with all study procedures. Exclusion Criteria:
• Known or suspected congenital or acquired immunodeficiency; or receipt of immunosuppressive therapy; or long-term systemic corticosteroid therapy - History of meningococcal infection - History of any neurological disorders - History of Guillain-Barré syndrome - History of an Arthus-type hypersensitivity reaction after a previous dose of tetanus toxoid-containing vaccine - At high risk for meningococcal infection during the study - Known systemic hypersensitivity to any of the study intervention components, or history of a life-threatening reaction to the study interventions used in the study or to a product containing any of the same substances - Self-reported thrombocytopenia, contraindicating intramuscular injection - Bleeding disorder, or receipt of anticoagulants in the 3 weeks preceding inclusion, contraindicating intramuscular injection - Chronic illness that, in the opinion of the investigator, is at a stage where it might interfere with study conduct or completion - Moderate or severe acute illness/infection (according to investigator judgment) or febrile illness (axillary temperature ≥37.5°C [99.5℉]) on the day of study intervention administration. A prospective participant should not be included in the study until the condition has resolved or the febrile event has subsided. - Receipt of any live vaccines within 14 days preceding the trial vaccination or planned receipt of any live vaccines in 14 days following trial vaccination, and receipt of any inactivated vaccines in 8 days preceding the trial vaccination or planned receipt of any live vaccines in 8 days following trial vaccination - For Cohort I (12 to 23 MoA): receipt of any other meningococcal vaccine except the meningococcal group A polysaccharide vaccine included in the NIP. The time since last vaccination of meningococcal group A or groups A and C polysaccharide vaccine of 6 months or less should be excluded. - For Cohorts II (6 to 11 MoA) and III (2 to 5 MoA): a vaccination history of any meningococcal vaccine. - Receipt of immune globulins, blood or blood-derived products in the past 3 months. - Receipt of oral or injectable antibiotic therapy within 72 hours prior to the first blood draw. - Participation at the time of study enrollment (or in the 4 weeks preceding the study intervention administration) or planned participation during the present study period in another clinical study investigating a vaccine, drug, medical device, or medical procedure. - In an emergency setting, or being hospitalized - Identified as a natural or adopted child of the Investigator or employee with direct involvement in the proposed study The above information is not intended to contain all considerations relevant to a participant's potential participation in a clinical trial.

Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org

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