Clinical Trial of Recombinant COVID-19 Vaccine (Sf9 Cells) in Children and Adolescents

This is a phase Ⅰ/Ⅱ, single-center, randomized, double-blind, placebo-controlled study, to evaluate the safety, tolerability and immunogenicity of the recombinant COVID-19 vaccine (Sf9 cells) in the subjects from healthy aged 6-17 years with immunization procedures 0, 21, 42 days and doses (10μg/20μg/40μg).

This is a phase Ⅰ/Ⅱ, single-center, randomized, double-blind, placebo-controlled study, to evaluate the safety, tolerability and immunogenicity of the recombinant COVID-19 vaccine (Sf9 cells) in the subjects from healthy aged 6-17 years with immunization procedures 0, 21, 42 days and doses (10μg/20μg/40μg). The phase Ⅰ clinical trials designed 4 research group, including immunization procedures 0, 21 42 days , three doses (10μg/0.25ml, 20μg/0.5ml, 40μg/1.0ml) and two ages group (6-11 and 12-17years): Each group including 30 participants. Vaccination or placebo group will be randomly assigned to receive in a 2:1 ratio, 120 in total. The phase Ⅱ clinical trials designed 4 research group, including immunization procedures 0, 21 42 days , three doses (10μg/0.25ml, 20μg/0.5ml, 40μg/1.0ml) and two ages group (6-11 and 12-17years): Each group including 120 participants. Vaccination or placebo group will be randomly assigned to receive in a 2:1 ratio, 480 in total.

Eligibility Criteria:
Inclusion Criteria:

* Aged 6-17 years；
* The subject and/or guardian can understand and voluntarily sign the informed consent form (double signature is required for 8-17 years old)；
* Reproductive women have a negative pregnancy test before each vaccination；
* The subjects are able and willing to comply with the requirements of the clinical trial protocol, and can complete the study follow-up for approximately 13.5 months.

Exclusion Criteria:

* History of SARS-CoV-2 infection.
* The COVID-19 antibody (IgG and IgM) screening was positive.
* History of asthma, history of allergy to vaccines or vaccine components, or severe adverse reactions to vaccines, such as urticaria, dyspnea, and angioedema.
* Congenital malformations or developmental disorders, genetic defects, severe malnutrition, etc.
* Autoimmune diseases or immunodeficiency/immunosuppression.
* Severe chronic diseases that cannot be controlled by drugs, severe cardiovascular diseases, diabetes, liver and kidney diseases, malignant tumors, etc.
* Severe neurological disease (epilepsy, convulsions or convulsions) or mental illness.
* Any condition caused by thyroid disease or history of thyroidectomy, hypersplenism, or splenectomy.
* Diagnosis of abnormal blood clotting function (for example, lack of clotting factors, coagulopathy, abnormal platelets) or obvious bruising or blood clotting.
* In the past 6 months, received immunosuppressive therapy, cytotoxic therapy, inhaled corticosteroids (excluding corticosteroid spray therapy for allergic rhinitis, and superficial corticosteroid therapy for acute uncomplicated dermatitis).
* Laboratory test results with clinically significant abnormalities (severity level 2 and above) (applicable to phase I clinical trials only).
* Received blood products in the last 3 months.
* Receive other study drugs or vaccines within the past 30 days.
* Vaccination against live attenuated vaccines in the past 30 days.
* Inactivated vaccine or subunit vaccine in the past 14 days.
* Acute disease or acute exacerbation of chronic disease in the last 7 days.
* Axillary temperature\> 37.0°C.
* According to the judgment of the investigator, the subject has other factors that are not suitable for participating in the clinical trial.

Subsequent dose exclusion criteria:

In this trial, the second/third dose of vaccination may be stopped in some cases. This includes allergic reactions, severe hypersensitivity reactions, or grade 3 or higher adverse reactions that cannot be tolerated after previous vaccination/placebo. If these reactions occur, the subject should not continue to receive the second/third vaccination.