This study is a randomized, double-blind 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 consistency of three consecutive lots, immunogenicity and safety of 23-valent pneumococcal polysaccharide vaccine of commercial scale in participants aged 40-65 years.

This study is a randomized, double-blind phase Ⅳ clinical trial in subjects aged 40-65 years to evaluate the lot-to-lot consistency,immunogenicity and safety of 23-valent pneumococcal polysaccharide vaccine of commercial scale.The experimental vaccine was manufactured by Sinovac Biotech Co., Ltd.A total of 1800 subjects will be enrolled.The subjects will be randomly divided into three groups in a ratio of 1:1:1 to received one dose of vaccine on day 0.

Inclusion Criteria:

• Adults aged 40-65 years in stable health;
• The subjects can understand and voluntarily sign the informed consent form;
• 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;
• Autoimmune disease or immune deficiency/immunosuppression;
• 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 7 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.