Eligibility Criteria:
Inclusion Criteria:
* Healthy subjects of ≥ 18 years old.
* The subject can understand and voluntarily sign the informed consent.
* The subject can The subject canprovide legal identification.
Exclusion Criteria:
* Have a history of close contact with a confirmed case of SARS-CoV-2, an asymptomatic infection in the previous 14 days, or a travel history/residential history in a community where a case has been reported.
* Have a history of contact with a person infected with SARS-CoV-2(a person with a positive nucleic acid test) in the previous 14 days.
* Patients with fever or respiratory symptoms who have been to middle or high-risk areas in the past 14 days or have exit history, or come from communities with case reports.
* In the past 14 days, there have been 2 or more cases of fever and/or respiratory symptoms in small areas such as homes, offices, school classes, etc.
* Have a history of SARS.
* Have a history of SARS-CoV-2 infection.
* Positive in SARS-CoV-2 IgG or IgM antibody screening.
* Positive in RT-PCR test of SARS-CoV-2 in throat swab.
* Positive in HIVantibody screening.
* Women who are breastfeeding, pregnant, or planning to become pregnant during the study period (based on the subject's self-report and blood pregnancy test results for women of childbearing age), or men who plan to conceive their partners during the study period.
* Subjects with body mass index (BMI) ≥35 kg/m2.
* Have a history of asthma, a history of vaccine or vaccine component allergy, have serious adverse reactions to the vaccine, such as urticaria, dyspnea, angioedema.
* Subjects with congenital malformations or developmental disorders, genetic defects, severe malnutrition, etc.
* Subjects with autoimmune diseases or immunodeficiency/immunosuppression.
* Subjects with severe chronic diseases, severe cardiovascular diseases, hypertension and diabetes that cannot be controlled by drugs, liver and kidney diseases, malignant tumors, etc.
* Subjects with severe neurological disease (epilepsy, convulsions or convulsions) or mental illness.
* Subjects with thyroid disease or history of thyroidectomy, no spleen, functional asthenia, and any spleen or splenectomy caused by any condition.
* Abnormal blood coagulation function diagnosed by a doctor (such as coagulation factor deficiency, coagulopathy, abnormal platelet) or obvious bruise or coagulation disorder.
* Have received immunosuppressant therapy, cytotoxic therapy, and inhaled corticosteroids in the past 6 months (excluding corticosteroid spray therapy for allergic rhinitis and surface corticosteroid therapy for acute non-complicated dermatitis).
* Physical examination or chest CT imaging reveals clinically significant abnormalities.
* Abnormal laboratory test results such as hematology and biochemistry that are beyond the reference value range and have clinical significance.
1. Routine blood test: white blood cell count, hemoglobin, platelet count.
2. Blood biochemical index detection: alanine aminotransferase (ALT), aspartate aminotransferase (AST), fasting blood glucose, C-reactive protein, total bilirubin (TBIL), creatinine (CR), creatine phosphokinase (CPK).
3. Urine routine indicators: urine protein (PRO), urine sugar, urine red blood cells.
4. Coagulation function test: prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT), fibrinogen (FIB).
* Have a long history of alcohol or drug abuse.
* Received blood products within 3 months before receiving trial vaccine.
* Received other study drugs within 30 days before receiving the trail vaccine.
* Received a live attenuated vaccine within 14 days before receiving the experimental vaccine.
* Received a subunit or inactivated vaccine within 7 days before receiving the experimental vaccine.
* Various acute or chronic diseases occurred in the past 7 days.
* Axillary body temperature\>37.0℃ before vaccination.
* According to the judgment of the investigator, the subject has any other factors that are not suitable for participating in the clinical trial.
Exclusion criteria of subsequent dose:
If one of the following (1) to (4) adverse events (AE) occurs, the vaccination is prohibited, but other research steps can be continued according to the investigator's judgment; if one of the following (5), (6) adverse events occurs , The investigator will judge whether to inoculate; if one of the following events (7) to (10) occurs, the vaccination can be postponed within the time window specified in the plan.
* (1)The subjects used the same vaccine other than the experimental vaccine during the study.
* (2)Any serious adverse reactions that are causally related to vaccination.
* (3)Severe allergic or hypersensitivity reactions after vaccination (including urticaria/skin rash within 30 minutes after vaccination).
* (4)Any confirmed or suspected autoimmune disease or immunodeficiency disease, including human immunodeficiency virus (HIV) infection.
* (5)Acute or new-onset chronic disease after vaccination.
* (6)Other reactions (including severe pain, severe swelling, severe activity limitation, persistent high fever, severe headache, or other systemic or local reactions) are judged by the investigator.
* (7)Acute illness at the time of vaccination (Acute illness refers to moderate or severe illness with or without fever).
* (8)Axillary temperature \>37.0℃ before vaccination.
* (9)Vaccination of subunit vaccine or inactivated vaccine within 7 days, live attenuated vaccine within 14 days.
* (10)According to the investigator's judgment, the subject has any other factors that are not suitable for vaccination.