Safety and Immunogenicity Study of Booster Vaccination in Different Doses of COVID-19 Vaccine (Vero Cell),Inactivated for Prevention of COVID-19

Study Overview
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Brief Summary
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This is a randomized, double-blinded, phase Ⅳ clinical trial of COVID-19 vaccine (Vero cell), Inactivated manufactured by Sinovac Life Sciences Co. , Ltd. The purpose of this study is to evaluate the safety and immunogenicity of booster vaccination using high-dosage or medium-dosage of COVID-19 vaccine (Vero cell), Inactivated in populations who have completed primary immunization 5-9 months

Detailed Description
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This study a randomized, double-blinded, phase Ⅳ clinical trial of COVID-19 vaccine (Vero cell), Inactivated.The purpose of this study is to evaluate the safety and immunogenicity of booster vaccination using high-dosage or medium-dosage of COVID-19 vaccine (Vero cell), Inactivated in populations who have completed primary immunization 5-9 months.A total of 340 subjects who have completed primary immunization using two-dose Coronavac® 5-9 months were be enrolled.All of subjects were be randomly divided into two groups in a 1:1 ratio to receive high-dosage or medium-dosage of COVID-19 vaccine (Vero cell), Inactivated.

Official Title
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A Randomized, Double-Blinded Clinical Trial to Evaluate the Immunogenicity Using Additional Dose of Medium-dosage or High-dosage COVID-19 Vaccine (Vero Cell), Inactivated in Populations Who Have Completed Primary Immunization 5-9 Months

Conditions
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COVID-19

Intervention / Treatment
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* Biological: High-dosage of COVID-19 vaccine (Vero cell), Inactivated
* Biological: Medium-dose COVID-19 Vaccine(Vero Cell),Inactivated


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy participants aged 18 years and above; Proven legal identity; The subjects can understand and voluntarily sign the informed consent form and be willing to complete the study in accordance with the study plan; Have received two doses of inactivated COVID-19 vaccine (CoronaVac®) manufactured by Sinovac Research & Development Co., Ltd and that is currently 5-9 months after the second dose. Exclusion Criteria: History of SARS-CoV-2 infection(laboratory confirmed); Have received three and more doses of inactivated COVID-19 vaccine; Known allergy to vaccines or vaccine ingredients, and serious adverse reactions to vaccines, such as urticaria, dyspnea, angioneurotic edema; Autoimmune disease such as systemic lupus erythematosus or immunodeficiency / immunosuppression such as AIDS, post-transplant; 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; 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; 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; Acute diseases or acute exacerbation of chronic diseases within 7 days prior to booster vaccination; Axillary temperature >37.0°C; Participated in other clinical trials prior to enrollment and during the followup period, or planned to participate in other clinical trials during the clinical trial period; According to the investigator's judgment, the subject has any other factors that are not suitable for participating in the clinical trial.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Experimental Group-High-dosage of COVID-19 vaccine (Vero cell), Inactivated<br>170 participants will receive one dose of booster vaccination with high-dosage of COVID-19 vaccine (Vero cell), Inactivated. | Biological: High-dosage of COVID-19 vaccine (Vero cell), Inactivated<br>* High-dose COVID-19 Vaccine(Vero Cell),Inactivated:1200SU inactivated SARS-CoV-2 virus in 0.5 mL of aluminium hydroxide solution per injection<br>* Other names: High-dose CoronaVac®;|
| Experimental: Experimental Group-Medium-dosage of COVID-19 vaccine (Vero cell), Inactivated<br>170 participants will receive one dose of booster vaccination with medium-dosage of COVID-19 vaccine (Vero cell), Inactivated. | Biological: Medium-dose COVID-19 Vaccine(Vero Cell),Inactivated<br>* Medium-dose COVID-19 Vaccine(Vero Cell),Inactivated: 600SU inactivated SARS-CoV-2 virus in 0.5 mL of aluminium hydroxide solution per injection<br>* Other names: Medium-dose CoronaVac®;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Immunogenicity index-GMT of neutralizing antibodies(CZ02 strain) | GMT of neutralizing antibodies(CZ02 strain) 14 days after the booster dose vaccination | 14 days after the booster dose vaccination | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Immunogenicity index-Seropositivity rate of neutralizing antibodies(CZ02 strain) | Seropositivity rate of neutralizing antibodies(CZ02 strain) 14 days after the booster dose vaccination | 14 days after the booster dose vaccination |