This is a randomized, double-blind, positive-controlled phase Ⅳ clinical trial of 23-valent pneumococcal polysaccharide vaccine manufactured by Sinovac Biotech Co., Ltd.The purpose of this study is to evaluate the immunogenicity and safety of 23-valent pneumococcal polysaccharide vaccine in population aged 2 years and older.

This study is a randomized, double-blind, positive-controlled phase Ⅳ clinical trial to evaluate the immunogenicity and safety of 23-valent pneumococcal polysaccharide vaccine in population aged 2 years and older.The experimental vaccine was manufactured by Sinovac Biotech Co., Ltd,the control vaccine was manufactured by Merck Sharp & Dohme.A total of 1800 subjects including 900 subjects aged 2~17 years,360 subjects aged 18~59 years and 540 subjects aged 60 years and above will be enrolled.Subjects in each age group will be randomly divided into two groups according to the ratio of 2:1, and received one dose of experimental vaccine or control vaccine.

Inclusion Criteria:

• Children aged 2 years and above in stable health;
• The subjects and/or guardians can understand and voluntarily sign the informed consent form (For subjects aged 8-17 years, both subjects and guardians need to sign the informed consent form.If the subject aged 16 to 17 years with full capacity for civil conduct and his/her labor income is his/her main source of living, the informed consent can be signed only by the subject himself/herself);
• Proven legal identity.

Exclusion Criteria:

• Have received any pneumococcal vaccine;
• History bacterial pneumonia or invasive pneumococcal infectious diseases caused by pneumococci and confirmed by culture.
• Women of childbearing age (menarche to premenopause) are pregnant (including positive urine pregnancy test), breastfeeding or planning pregnancy within 1 month;
• History of asthma, allergy to vaccines or vaccine components, and serious adverse reactions to vaccines, such as urticaria, dyspnea, and angioneurotic edema;
• Severe chronic diseases,such as severe cardiovascular diseases, hypertension(Systolic blood pressure ≥140mmHg and/or diastolic blood pressure ≥90mmHg) and diabetes that cannot be controlled by drugs, liver or kidney diseases,malignant tumors, etc.;
• Severe neurological disease (epilepsy, convulsions or convulsions) or mental illness;
• Diagnosed abnormal blood coagulation function (eg, lack of blood coagulation factors, blood coagulopathy, abnormal platelets) or obvious bruising or blood coagulation;
• Immunosuppressive therapy, cytotoxic therapy, inhaled corticosteroids (excluding allergic rhinitis corticosteroid spray therapy, acute noncomplicated dermatitis superficial corticosteroid therapy) in the past 6 months;
• A long history of alcohol or drug abuse;
• Receipt of blood products within in the past 3 months;
• Receipt of other investigational drugs within 30 days prior to receiving the investigational vaccine;
• Receipt of attenuated live vaccines or COVID-19 vaccines in the past 14 days;
• Receipt of inactivated or subunit vaccines in the past 7 days;
• Onset of various acute or chronic diseases within 3 days prior to the study;
• Underarm body temperature before vaccination>37.0°C;
• The subjects participated in other clinical trials during the follow-up period or will be planned to participate other clinical trials within 1 months;
• According to the investigator's judgment, the subject has any other factors that are not suitable for participating in the clinical trial.