Eligibility Criteria:
standard constrain:
1. Persons with full capacity for civil conduct aged ≥60 years;
2. Subjects voluntarily agree to participate in the research and sign an informed consent form, and can provide valid identification; understand and comply with the requirements of the trial protocol; have the ability to understand (non-illiterate) research procedures and participate in the planned follow-up;
3. Axillary body temperature \<37.3℃;
4. Female subjects and male subjects of childbearing age agree to take effective contraceptive measures during the study period.
Exclusion criteria:
1. The results of physical examination and laboratory examination before screening are abnormal and clinically significant as judged by clinicians, or systolic blood pressure ≥160mmHg and/or diastolic blood pressure ≥100mmHg before screening;
2. 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, blood vessels Neuroedema, etc.; or any previous history of serious side effects after the use of any vaccine or drug;
3. People with a history of SARS and SARS-CoV-2 (meet any of the following: ①Have a history of SARS and SARS-CoV-2 infection or onset; ②During this SRAS-CoV-2 epidemic, there are patients who have been diagnosed with the new crown/ Suspected patient contact history);
4. Have taken antipyretic or analgesic within 24 hours before the first dose of vaccination;
5. Inoculate subunit vaccine and/or inactivated vaccine within 14 days before the first dose of vaccine, and inoculate live attenuated vaccine within 30 days;
6. People suffering from the following diseases:
* Acute (within 72 hours) feverish illness;
* Suffering from digestive system diseases (such as diarrhea, abdominal pain, vomiting, etc.) in the past 7 days;
* Suffering from congenital malformations or developmental disorders, genetic defects, severe malnutrition, etc.;
* Congenital or acquired immunodeficiency or autoimmune disease history or receiving immunomodulator treatment within 6 months, such as hormones; or monoclonal antibodies; or thymosin; or interferon, etc.; but local medication (such as ointment, Eye drops, inhalation or nasal spray);
* Known to have been diagnosed with infectious diseases, such as: tuberculosis, viral hepatitis and/or human immunodeficiency virus HIV antibody positive or syphilis specific antibody positive;
* Neurological diseases or neurodevelopmental dysfunction (for example, migraine, epilepsy, stroke, seizures in the last three years, encephalopathy, focal neurological deficits, Guillain-Barré syndrome, encephalomyelitis or transverse myelitis; History of mental illness or family history;
⑦Functional asplenia, as well as any cause of aspleen or splenectomy;
⑧Severe chronic diseases or conditions that cannot be controlled smoothly in the advanced stage, such as diabetes and thyroid disease;
⑨Severe liver and kidney diseases; respiratory diseases that currently require daily drug treatment (for example, chronic obstructive pulmonary disease \[COPD\], asthma) or any treatment for exacerbation of respiratory diseases (for example, asthma exacerbation) in the last 5 years; suffering from severe History of cardiovascular disease (such as congestive heart failure, cardiomyopathy, ischemic heart disease, arrhythmia, conduction block, myocardial infarction, pulmonary heart disease) or myocarditis or pericarditis;
⑩Have thrombocytopenia, any coagulation dysfunction or receive anticoagulant treatment, etc.;
?Tumor patients;
7. Have received blood or blood-related products, including immunoglobulin, within 3 months; or plan to use it during the research period;
8. Those who are already pregnant (including a positive urine pregnancy test), or are breastfeeding;
9. Any research or unregistered products (drugs, vaccines, biological products or devices) other than research products have been used within 3 months, or planned to be used during the research period;
10. The investigator believes that any disease or condition in the subject may put the subject at an unacceptable risk; the subject cannot meet the requirements of the protocol; it interferes with the assessment of the vaccine response.