1. the subject has a history of contact with a person infected with sars-cov-2 (positive nucleic acid test) or a person suspected of being infected within 14 days; 2. have a history of severe allergies to any vaccines, foods, and drugs, such as urticaria, anaphylactic shock, skin eczema, allergic dyspnea, angioedema, etc.; 3. the subject has a history of hypersensitivity to any component of the study vaccine (sars-cov-2 mrna, dlin-mc3-dma, cholesterol, distearoylphosphatidylcholine, peg2000-dmg, phosphate buffer); 4. have a history of sars virus infection; 5. those with a medical history or family history of epileptic convulsions or convulsions, neurological diseases and mental diseases; 6. there is a history of thrombocytopenia or other coagulation disorders diagnosed by the hospital before enrollment; 7. the investigator judges that they are known or suspected to suffer from more serious diseases at the same time, including: respiratory diseases, tuberculosis, acute infection or active chronic disease, liver and kidney disease, cardiovascular disease (cardiopulmonary failure), and drug-uncontrollable hypertension (systolic blood pressure ≥ 160 mmhg, diastolic blood pressure ≥ 100 mmhg), malignant tumor, infection or allergic skin disease, hiv infection (test report can be provided); 8. congenital malformations, developmental disorders, or chronic diseases (such as down's syndrome, diabetes, sickle cell anemia or neurological disorders, guillain-barré syndrome) determined by the investigator to be unsuitable for participating in this research; 9. those with known immunological impairment or low function diagnosed by the hospital before enrollment; 10. there is evidence that he is a smoker, alcohol abuser and drug abuser; 11. positive sars-cov-2 nucleic acid test results and/or positive antibody test results before the first dose of vaccination; 12. female: a person with a positive urine pregnancy test, who is pregnant, breastfeeding, or has a pregnancy plan within 1 year; male: a person whose spouse has a pregnancy plan within 1 year; 13. any other investigational or unregistered product (drug, biological product, or device) is being used before the first dose of vaccine, or is planned to be used during the study; 14. those who received immune enhancement or immunosuppressive therapy within 6 months before the first dose of vaccine (continuous oral or infusion for more than 14 days); 15. has been diagnosed with congenital or acquired immunodeficiency, or suspected of having a systemic disease that may interfere with the conduct or completion of the study, such as: tuberculosis, hepatitis b, hepatitis c, human immunodeficiency virus (hiv); ), syphilis infection, etc.; 16. those who have received whole blood, plasma and immune globulin treatment within 6 months before the first dose of vaccine; 17. received other inactivated vaccines within 14 days before the first dose of vaccine, and received live attenuated vaccines within 28 days; 18. antipyretic, analgesic and anti-allergic drugs are being used within 3 days before enrollment; 19. subjects who, in the judgment of the investigator, cannot follow the research procedures, abide by the agreement, or plan to permanently relocate from the local area before the end of the study, or plan to leave the local area for a long time during the scheduled visit; 20. the relevant staff members involved in this research or their immediate family members (such as spouses, parents, siblings or children); 21. according to the judgment of the investigator, there are other circumstances that are not suitable for participating in this clinical trial.

1. the subject has a history of contact with a person infected with sars-cov-2 (positive nucleic acid test) or a person suspected of being infected within 14 days; 2. have a history of severe allergies to any vaccines, foods, and drugs, such as urticaria, anaphylactic shock, skin eczema, allergic dyspnea, angioedema, etc.; 3. the subject has a history of hypersensitivity to any component of the study vaccine (sars-cov-2 mrna, dlin-mc3-dma, cholesterol, distearoylphosphatidylcholine, peg2000-dmg, phosphate buffer); 4. have a history of sars virus infection; 5. those with a medical history or family history of epileptic convulsions or convulsions, neurological diseases and mental diseases; 6. there is a history of thrombocytopenia or other coagulation disorders diagnosed by the hospital before enrollment; 7. the investigator judges that they are known or suspected to suffer from more serious diseases at the same time, including: respiratory diseases, tuberculosis, acute infection or active chronic disease, liver and kidney disease, cardiovascular disease (cardiopulmonary failure), and drug-uncontrollable hypertension (systolic blood pressure ≥ 160 mmhg, diastolic blood pressure ≥ 100 mmhg), malignant tumor, infection or allergic skin disease, hiv infection (test report can be provided); 8. congenital malformations, developmental disorders, or chronic diseases (such as down's syndrome, diabetes, sickle cell anemia or neurological disorders, guillain-barré syndrome) determined by the investigator to be unsuitable for participating in this research; 9. those with known immunological impairment or low function diagnosed by the hospital before enrollment; 10. there is evidence that he is a smoker, alcohol abuser and drug abuser; 11. positive sars-cov-2 nucleic acid test results and/or positive antibody test results before the first dose of vaccination; 12. female: a person with a positive urine pregnancy test, who is pregnant, breastfeeding, or has a pregnancy plan within 1 year; male: a person whose spouse has a pregnancy plan within 1 year; 13. any other investigational or unregistered product (drug, biological product, or device) is being used before the first dose of vaccine, or is planned to be used during the study; 14. those who received immune enhancement or immunosuppressive therapy within 6 months before the first dose of vaccine (continuous oral or infusion for more than 14 days); 15. has been diagnosed with congenital or acquired immunodeficiency, or suspected of having a systemic disease that may interfere with the conduct or completion of the study, such as: tuberculosis, hepatitis b, hepatitis c, human immunodeficiency virus (hiv); ), syphilis infection, etc.; 16. those who have received whole blood, plasma and immune globulin treatment within 6 months before the first dose of vaccine; 17. received other inactivated vaccines within 14 days before the first dose of vaccine, and received live attenuated vaccines within 28 days; 18. antipyretic, analgesic and anti-allergic drugs are being used within 3 days before enrollment; 19. subjects who, in the judgment of the investigator, cannot follow the research procedures, abide by the agreement, or plan to permanently relocate from the local area before the end of the study, or plan to leave the local area for a long time during the scheduled visit; 20. the relevant staff members involved in this research or their immediate family members (such as spouses, parents, siblings or children); 21. according to the judgment of the investigator, there are other circumstances that are not suitable for participating in this clinical trial.

the subject has a history of contact with a person infected with sars-cov-2 (positive nucleic acid test) or a person suspected of being infected within 14 days; have a history of severe allergies to any vaccines, foods, and drugs, such as urticaria, anaphylactic shock, skin eczema, allergic dyspnea, angioedema, etc.; the subject has a history of hypersensitivity to any component of the study vaccine (sars-cov-2 mrna, dlin-mc3-dma, cholesterol, distearoylphosphatidylcholine, peg2000-dmg, phosphate buffer); have a history of sars virus infection; those with a medical history or family history of epileptic convulsions or convulsions, neurological diseases and mental diseases; there is a history of thrombocytopenia or other coagulation disorders diagnosed by the hospital before enrollment; the investigator judges that they are known or suspected to suffer from more serious diseases at the same time, including: respiratory diseases, tuberculosis, acute infection or active chronic disease, liver and kidney disease, cardiovascular disease (cardiopulmonary failure), and drug-uncontrollable hypertension (systolic blood pressure ≥ 160 mmhg, diastolic blood pressure ≥ 100 mmhg), malignant tumor, infection or allergic skin disease, hiv infection (test report can be provided); congenital malformations, developmental disorders, or chronic diseases (such as down's syndrome, diabetes, sickle cell anemia or neurological disorders, guillain-barré syndrome) determined by the investigator to be unsuitable for participating in this research; those with known immunological impairment or low function diagnosed by the hospital before enrollment; there is evidence that he is a smoker, alcohol abuser and drug abuser; positive sars-cov-2 nucleic acid test results and/or positive antibody test results before the first dose of vaccination; female: a person with a positive urine pregnancy test, who is pregnant, breastfeeding, or has a pregnancy plan within 1 year; male: a person whose spouse has a pregnancy plan within 1 year; any other investigational or unregistered product (drug, biological product, or device) is being used before the first dose of vaccine, or is planned to be used during the study; those who received immune enhancement or immunosuppressive therapy within 6 months before the first dose of vaccine (continuous oral or infusion for more than 14 days); has been diagnosed with congenital or acquired immunodeficiency, or suspected of having a systemic disease that may interfere with the conduct or completion of the study, such as: tuberculosis, hepatitis b, hepatitis c, human immunodeficiency virus (hiv); ), syphilis infection, etc.; those who have received whole blood, plasma and immune globulin treatment within 6 months before the first dose of vaccine; received other inactivated vaccines within 14 days before the first dose of vaccine, and received live attenuated vaccines within 28 days; antipyretic, analgesic and anti-allergic drugs are being used within 3 days before enrollment; subjects who, in the judgment of the investigator, cannot follow the research procedures, abide by the agreement, or plan to permanently relocate from the local area before the end of the study, or plan to leave the local area for a long time during the scheduled visit; the relevant staff members involved in this research or their immediate family members (such as spouses, parents, siblings or children); according to the judgment of the investigator, there are other circumstances that are not suitable for participating in this clinical trial.

the subject has a history of contact with a person infected with sars-cov-2 (positive nucleic acid test) or a person suspected of being infected within 14 days; have a history of severe allergies to any vaccines, foods, and drugs, such as urticaria, anaphylactic shock, skin eczema, allergic dyspnea, angioedema, etc.; the subject has a history of hypersensitivity to any component of the study vaccine (sars-cov-2 mrna, dlin-mc3-dma, cholesterol, distearoylphosphatidylcholine, peg2000-dmg, phosphate buffer); have a history of sars virus infection; those with a medical history or family history of epileptic convulsions or convulsions, neurological diseases and mental diseases; there is a history of thrombocytopenia or other coagulation disorders diagnosed by the hospital before enrollment; the investigator judges that they are known or suspected to suffer from more serious diseases at the same time, including: respiratory diseases, tuberculosis, acute infection or active chronic disease, liver and kidney disease, cardiovascular disease (cardiopulmonary failure), and drug-uncontrollable hypertension (systolic blood pressure ≥ 160 mmhg, diastolic blood pressure ≥ 100 mmhg), malignant tumor, infection or allergic skin disease, hiv infection (test report can be provided); congenital malformations, developmental disorders, or chronic diseases (such as down's syndrome, diabetes, sickle cell anemia or neurological disorders, guillain-barré syndrome) determined by the investigator to be unsuitable for participating in this research; those with known immunological impairment or low function diagnosed by the hospital before enrollment; there is evidence that he is a smoker, alcohol abuser and drug abuser; positive sars-cov-2 nucleic acid test results and/or positive antibody test results before the first dose of vaccination; female: a person with a positive urine pregnancy test, who is pregnant, breastfeeding, or has a pregnancy plan within 1 year; male: a person whose spouse has a pregnancy plan within 1 year; any other investigational or unregistered product (drug, biological product, or device) is being used before the first dose of vaccine, or is planned to be used during the study; those who received immune enhancement or immunosuppressive therapy within 6 months before the first dose of vaccine (continuous oral or infusion for more than 14 days); has been diagnosed with congenital or acquired immunodeficiency, or suspected of having a systemic disease that may interfere with the conduct or completion of the study, such as: tuberculosis, hepatitis b, hepatitis c, human immunodeficiency virus (hiv); ), syphilis infection, etc.; those who have received whole blood, plasma and immune globulin treatment within 6 months before the first dose of vaccine; received other inactivated vaccines within 14 days before the first dose of vaccine, and received live attenuated vaccines within 28 days; antipyretic, analgesic and anti-allergic drugs are being used within 3 days before enrollment; subjects who, in the judgment of the investigator, cannot follow the research procedures, abide by the agreement, or plan to permanently relocate from the local area before the end of the study, or plan to leave the local area for a long time during the scheduled visit; the relevant staff members involved in this research or their immediate family members (such as spouses, parents, siblings or children); according to the judgment of the investigator, there are other circumstances that are not suitable for participating in this clinical trial.