The purpose of this study was to explore the safety and immunogenicity of the experimental vaccine compared with the control vaccines. It is planed to enroll a total of 1,200 subjects, including 300 subjects in each of the 3-5 months old, 6-11 months old, 12-23 months old and 2-15 years old groups, who will be randomly assigned to the trial in a 1:1 ratio to study group or control group. The 3-5 month-old group will have three doses vaccination at 0, 1 and 2 month, and a booster dose at 12 months of age; the 6-11month-old and 12-23 month-old groups will each have total two doses vaccination; the 2-15 year-old group will have one dose vaccination.

The purpose of this study was to evaluate the safety and immunogenicity of the experimental vaccine(ACYW135 Meningococcal Polysaccharide Conjugate Vaccine) compared with the control vaccines(ACYW135 Meningococcal Polysaccharide Conjugate Vaccine and ACYW135 Meningococcal Polysaccharide Vaccine). It is planed to enroll a total of 1,200 subjects, including 300 subjects in each of the 3-5 months old, 6-11 months old, 12-23 months old and 2-15 years old groups, who will be randomly assigned to the trial in a 1:1 ratio to study group or control group. The 3-5 month-old group will have three doses vaccination at 0, 1 and 2 month, and a booster dose at 12 months of age; the 6-11month-old and 12-23 month-old groups will each have total two doses vaccination(at month 0, 1 or at month 0, 3); the 2-15 year-old group will have one dose vaccination. The immunogenicity and immune persistence will be evaluated by rabbit complement serum bactericidal assay.

Inclusion Criteria:

• 3~5 months old:

  1. 3~5 months old;
  2. The subject's legal guardian voluntarily agrees to his or her child's participation in this trial and signs an informed consent form;
  3. The subject and/or the subject's legal guardian can comply with the relevant requirements of the clinical trial protocol;
  4. Have not vaccinated by any meningococcal vaccine in the past.

• 6~23 months old:

  1. 6~23 months old;
  2. The subject's legal guardian voluntarily agrees to his or her child's participation in this trial and signs an informed consent form;
  3. The subject and/or the subject's legal guardian can comply with the relevant requirements of the clinical trial protocol;
  4. Have not vaccinated by any other meningococcal vaccines except meningococcal group A polysaccharide vaccine in the past. If have 1 dose vaccinated of meningococcal group A polysaccharide vaccine, it will be 3 months or more separated from the previous dose of meningococcal group A polysaccharide vaccine. If two doses of meningococcal group A polysaccharide vaccine have been vaccinated, the interval between the last dose of meningococcal group A polysaccharide vaccine should be more than 6 months or more.

• 2~15 years old:

  1. 2~15 years old;
  2. The subject's legal guardian voluntarily agrees to his or her child's participation in this trial and signs an informed consent form (subjects aged 8-15 years old are also required to sign an informed consent form);
  3. The subject and/or the subject's legal guardian can comply with the relevant requirements of the clinical trial protocol; Subjects aged 2 to 6 years old have not previously been vaccinated with any meningococcal vaccine other than meningococcal polysaccharide vaccine, and the interval between the previous dose of meningococcal polysaccharide vaccine and vaccination should be more than 12 months or more; 7~15 years old participants have not received any meningococcal vaccine in the past 3 years.

Exclusion Criteria:

1. The temperature before vaccination on the day of vaccination is >37.0℃;
2. Have a history of invasive disease caused by meningococci confirmed by culture;
3. Have a history of severe allergic reactions that require medical intervention (such as oral and throat swelling, dyspnea, hypotension or shock caused by allergies); have a history of allergies to vaccines or vaccine components (especially those allergic to diphtheria toxoid), and have concerns about vaccination History of other serious adverse reactions;
4. Those with a clearly diagnosed history of thrombocytopenia or other coagulation disorders, which may cause contraindications for intramuscular injection;
5. Suffer from acute disease or acute attack of chronic disease within 3 days before vaccination;
6. Have a history of epilepsy, progressive neurological disease, Guillain-Barré syndrome, convulsions (except simple febrile convulsions) and mental illness;
7. Known or suspected immunological dysfunction, including immunosuppressant treatment (radiation therapy, chemotherapy, corticosteroids, antimetabolites, cytotoxic drugs), human immunodeficiency virus (HIV) infection, etc.;
8. Known severe congenital malformations; suffering from developmental disabilities or clinically diagnosed serious chronic diseases (such as Down syndrome, diabetes, sickle cell anemia or neurological diseases);
9. Known or suspected to have serious diseases that are judged by the researcher to affect vaccination, including respiratory diseases, digestive system diseases, endocrine system diseases, immune system diseases, cardiovascular diseases, liver and kidney diseases, malignant tumors, skin diseases, etc. ;
10. Long-term use (continuous use for ≥14 days) of immunosuppressants or other immunomodulatory drugs (such as corticosteroids: prednisone or similar drugs) within 6 months before vaccination with the experimental vaccine, but local use (such as ointments, eye drops, inhalants, or nasal sprays), topical administration should not exceed the dosage recommended in the label;
11. Have received blood products including gamma globulin or immune globulin treatment within 3 months before vaccination (<3 months);
12. Asplenia or functional asplenia, asplenia or splenectomy caused by any condition;
13. Have been vaccinated with live attenuated vaccines within 14 days (including 14 days) before vaccination, and have been vaccinated with other subunits, inactivated vaccines or recombinant protein vaccines other than live attenuated vaccines within 7 days (including 7 days);
14. Currently participating in or planning to participate in other drug clinical trials during the entire trial period after receiving the experimental vaccine;
15. Any situation that the researcher believes may affect the evaluation of the trial.