1. History of COVID-19 2. Received partial or complete course of any type of COVID-19 vaccine. 3. History of close contact with a person infected or suspected of COVID-19 within 6 months prior to screening. 4. Positive test for SARS-CoV-2 infection, including but not limited to RT-PCR at screening 5. Positive rapid serological test (IgM or IgG against SARS-CoV-2) at screening or prior to first vaccination if available 6. Pregnant or breastfeeding or intending to become pregnant or father children within the projected duration of the trial 7. Currently working in an occupation with a high risk of exposure to SARS-CoV-2 (eg. Healthcare worker, emergency response personnel having direct interactions with or providing direct care to patients) 8. History of infection of Middle East Respiratory Syndrome (MERS), or Severe Acute Respiratory Syndrome (SARS) 9. Positive serology test results for hepatitis C virus antibody, HIV antibody, and/or hepatitis B virus surface antigen at Screening 10. Currently taking marketed, investigational, off-label product for the prevention of MERS, SARS, or COVID-19 11. Is currently participating in or has participated in a study with an investigational product within 30 days preceding Day 1 12. Fever (tympanic temperature greater than 37.5 degree C), dry cough, fatigue, nasal obstruction, runny nose, sore throat, myalgia, diarrhea, shortness of breath or dyspnea within 14 days before administration 13. Subjects with abnormal indicators, such as blood biochemistry, blood routine and urine routine deemed clinically significant by the investigator, or the value is beyond grade 1 per toxicity grading scale 14. History of severe allergic reactions (such as acute anaphylaxis, urticaria, skin eczema, dyspnea, angioneurotic edema or abdominal pain) or allergy to known composition of PIKA COVID-19 vaccine 15. History of convulsion, epilepsy, encephalopathy or severe mental illness 16. Diagnosed with congenital malformations or developmental disorders, genetic defects, severe malnutrition 17. Diagnosed with severe liver and kidney diseases, uncontrollable hypertension (systolic pressure greater than 140 mmHg, diastolic pressure greater than 90 mmHg), diabetic complications, malignant tumors, acute viral or bacterial infections or acute onset of chronic disease 18. Diagnosed with congenital or acquired immune deficiency, HIV infection, lymphoma, leukemia or other autoimmune diseases 19. History of coagulation dysfunction (e.g. Coagulation factor deficiency, coagulation disease) 20. Vaccinated with live attenuated vaccine within 1 month, or other vaccine within 14 days before vaccination 21. Receiving immunotherapy or inhibitor therapy within 3 months (consistently oral or infusion for more than 14 days) 22. Received systemic immunosuppressants within 4 months prior to vaccination, or anticipating the need for immunosuppressant at any time during participation in the study. Topical or inhaled treatment is allowed if not used within 14 days prior to vaccination. 23. Receiving blood products within 3 months before administration 24. History of alcohol or drug abuse within 3 years before first vaccination 25. Has donated 450ml or greater of blood within 28 days prior to vaccination 26. History of anaphylaxis or angioedema including but not limited to history of anaphylaxis after any vaccine. 27. Any condition that, in the opinion of the investigator, would pose a health risk to the subject if e

1. History of COVID-19 2. Received partial or complete course of any type of COVID-19 vaccine. 3. History of close contact with a person infected or suspected of COVID-19 within 6 months prior to screening. 4. Positive test for SARS-CoV-2 infection, including but not limited to RT-PCR at screening 5. Positive rapid serological test (IgM or IgG against SARS-CoV-2) at screening or prior to first vaccination if available 6. Pregnant or breastfeeding or intending to become pregnant or father children within the projected duration of the trial 7. Currently working in an occupation with a high risk of exposure to SARS-CoV-2 (eg. Healthcare worker, emergency response personnel having direct interactions with or providing direct care to patients) 8. History of infection of Middle East Respiratory Syndrome (MERS), or Severe Acute Respiratory Syndrome (SARS) 9. Positive serology test results for hepatitis C virus antibody, HIV antibody, and/or hepatitis B virus surface antigen at Screening 10. Currently taking marketed, investigational, off-label product for the prevention of MERS, SARS, or COVID-19 11. Is currently participating in or has participated in a study with an investigational product within 30 days preceding Day 1 12. Fever (tympanic temperature greater than 37.5 degree C), dry cough, fatigue, nasal obstruction, runny nose, sore throat, myalgia, diarrhea, shortness of breath or dyspnea within 14 days before administration 13. Subjects with abnormal indicators, such as blood biochemistry, blood routine and urine routine deemed clinically significant by the investigator, or the value is beyond grade 1 per toxicity grading scale 14. History of severe allergic reactions (such as acute anaphylaxis, urticaria, skin eczema, dyspnea, angioneurotic edema or abdominal pain) or allergy to known composition of PIKA COVID-19 vaccine 15. History of convulsion, epilepsy, encephalopathy or severe mental illness 16. Diagnosed with congenital malformations or developmental disorders, genetic defects, severe malnutrition 17. Diagnosed with severe liver and kidney diseases, uncontrollable hypertension (systolic pressure greater than 140 mmHg, diastolic pressure greater than 90 mmHg), diabetic complications, malignant tumors, acute viral or bacterial infections or acute onset of chronic disease 18. Diagnosed with congenital or acquired immune deficiency, HIV infection, lymphoma, leukemia or other autoimmune diseases 19. History of coagulation dysfunction (e.g. Coagulation factor deficiency, coagulation disease) 20. Vaccinated with live attenuated vaccine within 1 month, or other vaccine within 14 days before vaccination 21. Receiving immunotherapy or inhibitor therapy within 3 months (consistently oral or infusion for more than 14 days) 22. Received systemic immunosuppressants within 4 months prior to vaccination, or anticipating the need for immunosuppressant at any time during participation in the study. Topical or inhaled treatment is allowed if not used within 14 days prior to vaccination. 23. Receiving blood products within 3 months before administration 24. History of alcohol or drug abuse within 3 years before first vaccination 25. Has donated 450ml or greater of blood within 28 days prior to vaccination 26. History of anaphylaxis or angioedema including but not limited to history of anaphylaxis after any vaccine. 27. Any condition that, in the opinion of the investigator, would pose a health risk to the subject if e