Phase Ⅲ Trial of Group ACYW135 Meningococcal Conjugate Vaccine in Children Aged 6-11 Months

The goal of this clinical trial is to evaluate the immunogenicity, safety, and persistence of the immune response of a group ACYW135 meningococcal conjugate vaccine in healthy children aged 6 to 11 months.

The main questions it aims to answer are:

Is the immune response induced by the investigational vaccine non-inferior to that of the licensed control vaccine following the primary series? What is the safety profile of the investigational vaccine during the primary series and booster dose? Does the investigational vaccine provide durable immune persistence up to 18 months of age? What is the immunogenicity of a booster dose administered at 18 months of age? Researchers will compare the investigational vaccine group with the active comparator group (licensed group ACYW135 meningococcal conjugate vaccine (CRM197 carrier), CanSinoBIO) during the primary immunization phase. Only the investigational group will receive a booster dose at 18 months of age to evaluate booster immunogenicity and safety.

Participants will:

Be randomly assigned in a 1:1 ratio to receive either two doses of the investigational vaccine or two doses of the control vaccine according to a 0,1-month schedule during the primary immunization phase; In the investigational group only, receive a booster dose at 18 months of age; Provide blood samples at three time points: before primary vaccination, 30 days after primary vaccination, and at 18 months of age to assess primary immunogenicity and immune persistence; In the investigational group only, provide an additional blood sample 30 days after the booster dose to assess booster immunogenicity; Be observed for 30 minutes after each dose for immediate adverse reactions; Have solicited local and systemic adverse events recorded for 7 days after each dose using diary cards; Have unsolicited adverse events recorded for 30 days after each dose using diary cards; Be monitored for serious adverse events for at least 6 months after the last dose administered; A total of 1040 participants will be enrolled.