Clinical Trial of COVID-19 Vaccine（SARS-CoV-2 Variant(Omicron BA.5) mRNA Vaccine） in Participants Aged 18 Years and Over

Study Overview
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Brief Summary
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This is a single-center, randomized, blinded, placebo-controlled clinical trial to evaluate the protective efficacy, safety and immunogenicity of one dose of the SARS-CoV-2 variant (Omicron BA.5) mRNA vaccine in people aged 18 years and older who had received two or three doses of inactivated COVID-19 vaccine.

Official Title
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A Single-center, Randomized, Blinded, Placebo-controlled Clinical Trial to Evaluate the Protective Efficacy, Safety and Immunogenicity of One Dose of the SARS-CoV-2 Variant (Omicron BA.5) mRNA Vaccine in People Aged 18 Years and Older Who Had Received Two or Three Doses of Inactivated COVID-19 Vaccine

Conditions
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SARS-CoV-2

Intervention / Treatment
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* Biological: SARS-CoV-2 Variant (Omicron BA.5) mRNA vaccine
* Drug: Saline solution


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Both male and female adults aged 18 and above who can provide identification; Know the contents of the informed consent form and the situation of the vaccination, sign the informed consent form voluntarily, and have the ability to use the thermometer, scale and fill in the diary card and contact card as required; Ability to communicate well with researchers, understand and comply with the requirements of the study; Two or three doses of COVID-19 inactivated vaccine have been completed and ≥6 months have passed since the last dose of COVID-19 inactivated vaccine; Healthy subjects or subjects with mild underlying diseases [stable condition with no worsening condition (no need for hospitalization or no major adjustment in treatment regimen, etc.) for at least 3 months prior to inclusion in the study]; Women who are not possibility to have children (amenorrhea for at least 1 year or surgical sterilization with medical records) or who are known not to be pregnant or lactating and who have used effective contraception for nearly 14 days before vaccination (e.g., Intrauterine or implantable contraceptive devices,oral contraceptives, injected or embedded contraceptives, slow-release topical contraceptives, intrauterine devices (IUD), condoms (male), diaphragm, cervical cap, etc.) (provide negative proof of pregnancy within 48 hours); SARS-CoV-2 etiology test (RT-PCR) was negative within 48 hours. Exclusion Criteria: Abnormal vital signs that are clinically significant (e.g. abnormal controlled blood pressure); Have been infected with COVID-19 or used any COVID-19 prophylactic medication other than 3 doses of COVID-19 inactivated vaccine within the last 6 months (for example, a history of any other non-COVID-19 inactivated vaccine on or off the market, or 1 or 4 doses of COVID-19 inactivated vaccine); History of severe acute respiratory syndrome (SARS), Middle East Respiratory Syndrome (MERS) and other human coronavirus infection or disease history; Axillary temperature ≥37.3℃ or fever within 24 hours on the day of vaccination (axillary temperature ≥37.3℃/ mouth temperature ≥37.5℃); A history of severe allergic reactions or allergic reactions to vaccines or drugs, such as urticaria, severe eczema, dyspnea, laryngeal edema, angioneurotic edema, etc.; Vaccination of any vaccine within 28 days prior to study vaccination; Enrolled in a clinical study of another drug within 28 days before vaccination or planned to participate in a clinical study of another drug within 6 months after vaccination; Have a genetic tendency to bleed or abnormal coagulation function (e.g. cytokine deficiency, coagulation disorder or thrombocytopenia), or a history of severe bleeding; A known history or diagnosis of a disease affecting immune system function, such as cancer (other than basal cell carcinoma of the skin), congenital or acquired immunodeficiency (e.g., HIV infection), uncontrolled autoimmune disease, etc.; Asplenia or functional asplenia; Long-term use (continuous use ≥14 days) of immunosuppressants or other immunomodulatory drugs (e.g., cortisol: prednisone or similar drugs) within 6 months prior to study vaccination; Interferon, etc.), but topical use (such as ointments, eye drops, inhalants or nasal sprays) is permitted, and the dose of topical use shall not exceed that recommended in the instructions; Received immunoglobulin and/or blood products within 3 months prior to study vaccination; Suspected or known alcohol dependence or drug abuse; Other factors considered inappropriate to be included in the study.

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: SARS-CoV-2 Variant (Omicron BA.5) mRNA vaccine<br> | Biological: SARS-CoV-2 Variant (Omicron BA.5) mRNA vaccine<br>* One dose was administered by intramuscular injection, 100μg，1.0ml/dose<br>|
| Placebo Comparator: Placebo<br> | Drug: Saline solution<br>* One dose was administered by intramuscular injection, 0.5ml/vial<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Person-year incidence of symptomatic COVID-19 of any severity among persons 18 years of age and older who had received 2 or 3 doses of inactivated COVID-19 vaccine | Person-year incidence of symptomatic COVID-19 of any severity 14 days after vaccination (≥D14) with a booster dose of study vaccine or placebo among persons 18 years of age and older who had received 2 or 3 doses of inactivated COVID-19 vaccine | 14 days after vaccination or placebo | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Person-year incidence of severe and critical COVID-19 in persons aged 18 years and older who had received 2 or 3 doses of inactivated COVID-19 vaccine | Person-year incidence of severe and critical COVID-19 after 14 days (≥D14) after booster immunization with 1 dose of study vaccine or placebo in persons aged 18 years and older who had received 2 or 3 doses of inactivated COVID-19 vaccine | 14 days after vaccination or placebo | 
| Person-year incidence of COVID-19 resulting in death in persons aged 18 years and older who had received 2 or 3 doses of inactivated COVID-19 vaccine | Person-year incidence of COVID-19 resulting in death 14 days (≥D14) after booster vaccination with 1 dose of study vaccine or placebo in persons aged 18 years and older who had received 2 or 3 doses of inactivated COVID-19 vaccine | 14 days after vaccination or placebo | 
| Person-year incidence of symptomatic COVID-19 of any severity among persons aged 18-59 years and ≥60 years who had received 2 or 3 doses of inactivated COVID-19 vaccine | Person-year incidence of symptomatic COVID-19 of any severity 14 days (≥D14) after booster immunization with 1 dose of study vaccine or placebo among persons aged 18-59 years and ≥60 years who had received 2 or 3 doses of inactivated COVID-19 vaccine | 14 days after vaccination or placebo | 
| GMT of true virus neutralizing antibodies against the current major circulating strain of SARS-CoV-2 in subjects in the immunization subgroup | In the immunization subgroup, true virus neutralizing antibodies GMT against the current major circulating strain of SARS-CoV-2 were detected 7 days, 14 days, 28 days, 3 months, and 6 months after receiving one dose of study vaccine or placebo | 7 days, 14 days, 28 days, 3 months, and 6 months after vaccination or placebo | 
| GMI of true virus neutralizing antibodies against the current major circulating strain of SARS-CoV-2 in subjects in the immunization subgroup | In the immunization subgroup, true virus neutralizing antibodies GMI against the current major circulating strain of SARS-CoV-2 were detected 7 days, 14 days, 28 days, 3 months, and 6 months after receiving one dose of study vaccine or placebo | 7 days, 14 days, 28 days, 3 months, and 6 months after vaccination or placebo | 
| SCR of true virus neutralizing antibodies against the current major circulating strain of SARS-CoV-2 in subjects in the immunization subgroup | In the immunization subgroup, true virus neutralizing antibodies SCR against the current major circulating strain of SARS-CoV-2 were detected 7 days, 14 days, 28 days, 3 months, and 6 months after receiving one dose of study vaccine or placebo | 7 days, 14 days, 28 days, 3 months, and 6 months after vaccination or placebo | 
| GMT of S protein IgG against the current major circulating strain of SARS-CoV-2 in the immunization subgroup | GMT of S protein IgG against the current major circulating strain of SARS-CoV-2 7 days, 14 days, 28 days, 3 months, and 6 months after receiving one dose of study vaccine or placebo in the immunization subgroup | 7 days, 14 days, 28 days, 3 months, and 6 months after vaccination or placebo | 
| GMI of S protein IgG against the current major circulating strain of SARS-CoV-2 in the immunization subgroup | GMI of S protein IgG against the current major circulating strain of SARS-CoV-2 7 days, 14 days, 28 days, 3 months, and 6 months after receiving one dose of study vaccine or placebo in the immunization subgroup | 7 days, 14 days, 28 days, 3 months, and 6 months after vaccination or placebo | 
| SCR of S protein IgG against the current major circulating strain of SARS-CoV-2 in the immunization subgroup | SCR of S protein IgG against the current major circulating strain of SARS-CoV-2 7 days, 14 days, 28 days, 3 months, and 6 months after receiving one dose of study vaccine or placebo in the immunization subgroup | 7 days, 14 days, 28 days, 3 months, and 6 months after vaccination or placebo | 
| Incidence of adverse events in people aged 18 years and older who had received 2 or 3 doses of inactivated COVID-19 vaccine | Incidence of adverse events at 30 minutes, 0-14 days and 0-28 days after booster vaccination of 1 dose of study vaccine or placebo in people aged 18 years and older who had received 2 or 3 doses of inactivated COVID-19 vaccine | 30 minutes, 0-14 days and 0-28 days after vaccination or placebo | 
| Incidence of serious adverse events (SAE) in people aged 18 years and older who had received 2 or 3 doses of inactivated COVID-19 vaccine | Incidence of serious adverse events (SAE) within 6 months after booster immunization with 1 dose of study vaccine or placebo in people aged 18 years and older who had received 2 or 3 doses of inactivated COVID-19 vaccine | within 6 months after vaccination or placebo | 
| Incidence of AESI in people aged 18 years and older who had received 2 or 3 doses of inactivated COVID-19 vaccine | Incidence of AESI within 6 months after booster immunization with 1 dose of study vaccine or placebo in people aged 18 years and older who had received 2 or 3 doses of inactivated COVID-19 vaccine | within 6 months after vaccination or placebo | 
| Pregnancy events among persons aged 18 years and older who had received 2 or 3 doses of inactivated COVID-19 vaccine | Pregnancy events within 6 months after booster vaccination with 1 dose of study vaccine or placebo (including: pregnancy outcomes, delivery characteristics, delivery of newborns, and growth and development within 1 month after birth) among persons aged 18 years and older who had received 2 or 3 doses of inactivated COVID-19 vaccine | within 6 months after vaccination or placebo |