A total of 900 subjects are planned to be randomly divided into 2 doses of low-dose experimental vaccine group, 2 doses of high-dose experimental vaccine group, 2 doses of placebo group, 3 doses of low-dose experimental vaccine group, 3 doses of high-dose experimental vaccine group and 3 doses of placebo group, the sample size of each group was 150 cases.

A total of 900 subjects are planned to be randomly divided into 2 doses of low-dose experimental vaccine group, 2 doses of high-dose experimental vaccine group, 2 doses of placebo group, 3 doses of low-dose experimental vaccine group, 3 doses of high-dose experimental vaccine group and 3 doses of placebo group, the sample size of each group was 150 cases.

Subjects in the 2 dose group were injected with 2 doses of test vaccine or placebo in the upper arm deltoid muscle according to the 0,1 month immunization program, and subjects in the 3 dose group were injected with 3 doses of test vaccine or placebo in the upper arm deltoid muscle according to the 0, 1, 2 month immunization program .

Inclusion Criteria:

• Persons with full civil capacity aged 18-59 years (both included);
• The subjects themselves voluntarily agreed to participate in the study, and signed an informed consent form, and can provide valid identification; understand and comply with the requirements of the trial protocol;
• Body temperature under armpit <37.3℃;
• Female and male subjects of childbearing age agreed to take effective contraceptive measures during the study.

Exclusion Criteria:

• The vital signs and physical examination results of the population specified in the plan have clinical significance as determined by the clinician;
• A history of severe allergies to any component of the test vaccine, including aluminum preparations, such as: anaphylactic shock, allergic laryngeal edema, allergic purpura, thrombocytopenic purpura, local allergic necrosis (Arthus reaction), dyspnea, vascular neuropathy Edema, etc.; or any previous history of serious side effects after using any vaccine or drug;
• Those with a history of SARS and SARS-CoV-2 (meet any of the following: ① previous history of SARS and SARS-CoV-2 infection or morbidity; ② during the current SARS-CoV-2 epidemic, there are patients diagnosed/suspected with the new crown Contact history);
• Have taken antipyretics or painkillers within 24 hours before the first dose of vaccination;
• Within 14 days before the first dose of vaccination, subunit vaccines, inactivated vaccines, and live attenuated vaccines within 30 days;
• People with the following diseases: Acute febrile disease; Digestive diseases (eg, diarrhea, abdominal pain, vomiting, etc.) in the past 7 days; Congenital malformations or developmental disorders, genetic defects, severe malnutrition, etc.; Congenital or Acquired immunodeficiency or a history of autoimmune diseases or treatment with immunomodulators within 6 months, such as hormones; or monoclonal antibodies; or thymosin; or interferon, etc.; however, topical medications (such as ointment, eye drops, Inhalation or nasal spray); known to be diagnosed with infectious diseases, such as: patients with tuberculosis, viral hepatitis and/or human immunodeficiency virus HIV positive or syphilis specific antibody positive; neurological disease or Neurodevelopmental dysplasia (eg, migraine, epilepsy, stroke, seizures in the last three years, encephalopathy, focal neurological deficit, Guillain-Barré syndrome, encephalomyelitis or transverse myelitis); history of psychiatric illness or family History; functional spleenlessness, and spleenlessness or splenectomy for any reason; severe chronic disease or disease in progress that cannot be controlled smoothly, such as diabetes, thyroid disease; severe liver and kidney disease; respiratory tract that currently requires daily medication Diseases (eg, chronic obstructive pulmonary disease [COPD], asthma) or any treatment that exacerbates respiratory diseases (eg, asthma exacerbations) within the last 5 years; has severe cardiovascular disease (eg, congestive heart failure, cardiomyopathy, Ischemic heart disease, arrhythmia, conduction block, myocardial infarction, pulmonary heart disease) or a history of myocarditis or pericarditis; with thrombocytopenia, any coagulopathy, or treatment with anticoagulants; tumor patients;
• Have received blood or blood-related products, including immunoglobulin, within 3 months; or plan to use it during the study;
• Women who are breastfeeding or pregnant (including a positive urine pregnancy test);
• Have used any research or unregistered product (medicine, vaccine, biological product or device) other than the research product within 3 months, or plan to use it during the research;
• The researchers believe that any disease or condition in the subject may put the subject at an unacceptable risk; the subject cannot meet the protocol requirements; and interfere with the assessment of vaccine response.