Immunogenicity and Safety of an Inactivated COVID-19 Vaccine

This study is a randomized, placebo-controlled and opened, phase 4 clinical trial to evaluate the safety and immunogenicity of an inactivated COVID-19 vaccine(CoronaVac）in healthy population aged 18 years and older . The experimental vaccine is manufactured by Sinovac Research and Development Co.,Ltd. A total of 270 healthy subjects will be enrolled, including 135 adults aged 18-59 years and 135 elderly elderly aged 60 years and older. Subjects in each age group will be divided into two groups in a ratio of 1:1. Subjects in the experimental group will receive two doses of CoronaVac on day 0 and day 28. Subjects in the control group will receive one dose of 23-valent Pneumococcal Polysaccharide Vaccine on day 0 and one dose of Inactivated Hepatitis A Vaccine on day 28.

Inclusion criteria

• Healthy population aged 18 years and above;
• The subjects can understand and voluntarily sign the informed consent form;
• Proven legal identity.

Exclusion criteria

• History of SARS-CoV-2 infection;
• Have received any COVID-19 vaccine;
• Participants with abnormal fasting blood glucose or diabetes;
• History of asthma, history of allergy to the vaccine or vaccine components,or serious adverse reactions to the vaccine, such as urticaria, dyspnea,and angioedema;
• Autoimmune disease or immunodeficiency / immunosuppression;
• Severe chronic diseases, severe cardiovascular diseases, hypertension 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;
• Thyroid disease or history of thyroidectomy, spleenlessness, functional spleenlessness, spleenlessness or splenectomy resulting from any condition;
• Diagnosed abnormal blood coagulation function (eg, lack of blood coagulation factors, blood coagulopathy, abnormal platelets) or obvious bruising or blood coagulation;
• Diseases or factors that are prone to thrombosis or bleeding, such as thrombophlebitis, major surgery/trauma, hereditary thrombotic disorder, sepsis, inflammatory bowel disease, severe varicose veins, May-Thurner syndrome, fibrinolytic activity enhancement disease, history of cardiac stent surgery, allergic purpura, etc.;
• Immunosuppressive therapy, cytotoxic therapy, inhaled corticosteroids (excluding allergic rhinitis corticosteroid spray therapy, acute noncomplicated dermatitis superficial corticosteroid therapy) in the past 6 months;
• Abnormal hematological laboratory test results outside the reference range during previous physical examination within one year: Blood routine indicators (white blood cell count, hemoglobin, platelet count), Coagulation function test (prothrombin time PT, activated partial prothrombin time APTT, fibrinogen FIB, thrombin time TT, international standardized ratio INR, D-dimer), other indicators (blood glucose, platelet factor 4 HIT ELISA, erythrocyte sedimentation rate);
• History of alcohol or drug abuse;
• Receipt of blood products within in the past 3 months;
• Receipt of other investigational drugs in the past 30 days;
• Receipt of attenuated live vaccines in the past 14 days;
• Receipt of inactivated or subunit vaccines in the past 7 days;
• Axillary temperature >37.0°C;
• Already pregnant (including a positive urine pregnancy test) or are breastfeeding, planning to get pregnant within 3 months;
• History of taking aspirin drugs and other drugs that affect blood coagulation;
• According to the investigator's judgment, the subject has any other factors that are not suitable for participating in the clinical trial.