Phase Ⅲ Trial of Group ACYW135 Meningococcal Conjugate Vaccine in Children Aged 3-5 Months

The goal of this clinical trial is to evaluate the immunogenicity, safety, and immune persistence of the primary series of an investigational group ACYW135 meningococcal conjugate vaccine, as well as the immunogenicity and safety of a booster dose administered at 12 months of age, in healthy children aged 3 to 5 months.

The main questions it aims to answer are:

Is the immune response induced by the primary series of the investigational vaccine non-inferior to that of the licensed control vaccine? What is the safety profile of the investigational vaccine during the primary series and booster dose? Does the investigational vaccine provide immune persistence up to 12 months of age? What is the immunogenicity of a booster dose administered at 12 months of age? Researchers will compare the investigational vaccine group with the active comparator group (CanSinoBIO MCV-ACYW) during both the primary immunization phase and the booster phase.

Participants will:

Be randomly assigned in a 1:1 ratio to receive either three doses of the investigational vaccine or three doses of the control vaccine according to a 0,1,2-month schedule during the primary immunization phase; Receive a booster dose at 12 months of age (either investigational vaccine or control vaccine according to group assignment); Provide blood samples at four time points: before primary vaccination, 30 days after primary vaccination, before booster vaccination (12 months of age), and 30 days after booster vaccination; 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 880 participants will be enrolled.