A Clinical Trial of ACYW135 Group Meningococcal Polysaccharide Conjugate Vaccine (CRM197 Vector) in a 4 to 6 Year-old Population

Inclusion Criteria: * Children aged 4\~6 years old * Complete at least two doses of basic immunization with polysaccharide influenza vaccine according to the immunization program * The legal guardian or delegate has given informed consent, voluntarily signed the informed consent form, and is able to comply with the requirements of the clinical study protocol Exclusion Criteria: * Fever before inoculation, axillary temperature \>37.0℃ * Previous history of immunization with meningococcal polysaccharide conjugate vaccine * Congenital malformations or developmental disorders, genetic defects, severe malnutrition, etc. * History of epilepsy, convulsions or seizures or a history of psychiatric illness or family history * Volunteers with current meningitis or a history of meningitis * Volunteers treated with immunosuppressive therapy, cytotoxic therapy, glucocorticoids (excluding topical treatment, surface treatment for acute uncomplicated dermatitis, spray treatment for allergic rhinitis) within the past 6 months (\<6 months) * Received blood/plasma products or immunoglobulins within 60 days (\<60 days) prior to study vaccination or planned to receive blood/plasma products or immunoglobulins throughout the study period * Suffering from serious chronic diseases or conditions that are in a progressive stage and cannot be controlled smoothly, such as thyroid disease * Volunteers with known or suspected diseases that are judged by the investigator to affect vaccination such as seve…