Immunogenicity and Safety Study of an Investigational Quadrivalent Meningococcal Conjugate Vaccine Administered in Healthy Infants and Toddlers in China

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).