The immunogenicity and safety of AdCLD-CoV19-1 OMI (5.0x10^10 VP (0.5 mL)/dose/Vial) administered as a booster in healthy adults aged 19 years old and above will be evaluated. Outcome assessment will be performed in comparison with Comirnaty Bivalent.

Inclusion Criteria:

1. Individual aged 19 and above and willing to provide written informed consent to participate study voluntarily.

2. Individual fall under one or more of the following at the date of IP administration

   • At least past 16 weeks (112 days) without additional COVID-19 vaccination since the last COVID-19 vaccination.
   • At least past 16 weeks (112 days) since the release of quarantine due to COVID-19 confirmation.

3. Individual who agrees to use medically acceptable contraceptive methods† for at least 4 weeks prior to screening and 12 weeks post IP administration.

4. Individual who agrees not to donate or transfuse blood (including whole blood, plasma components, platelet components, platelet plasma components) throughout the study participation.

Exclusion Criteria:

1. Individual fall under one or more of the following at the date of IP administration

   • History of COVID-19 within 16 weeks (-111~0 days) or considered to be infected prior to IP administration.
   • History of receiving COVID-19 vaccine within 16 weeks (-111~0 days) prior to IP administration.

2. Clinically significant abnormalities on clinical laboratory tests, electrocardiograms, and chest X-rays performed during screening visit.

3. Positive HIV test result on the screening test.

4. Acute febrile illness with (≥38°C), or any suspected infectious diseases, or COVID-19-like symptoms (cough, shortness of breath, chills, myalgia, headache, sore throat, loss of taste/smell, etc.) within 3 days prior to administration of IP.

5. Any serious medical or psychiatric disease which in opinion of investigator judges unable to participate.

   • Respiratory diseases: Asthma, Chronic Obstructive Pulmonary Disease (COPD), active or latent tuberculosis which require medication, or individual who has received treatment due to worsening of the listed respiratory disease within 5 years prior to administration of IP.
   • Serious cardiovascular diseases: Congestive heart failure, coronary artery disease, myocardial infarction, uncontrolled hypertension, thrombocytopenia or venous thrombosis, capillary leakage syndrome, myocarditis, pericarditis, etc.
   • Neurologic diseases: Epilepsy, seizure within past 3 years, migraine, stroke, encephalopathy, Guillain-Barre Syndrome, encephalomyelitis, transverse myelitis, etc.
   • Malignant cancer diagnosed within past 5 years (skin basal cell and squamous cell carcinoma are excluded).
   • Immune function disorders including autoimmune hypothyroidism, psoriasis.
   • Immunodeficiency diseases.
   • History of dependently administering psychotropic drugs or narcotic analgesics within 24 weeks prior to administration of IP, or psychiatric disease or behavioral impairment that, in the opinion of the investigator, could interfere with the participant's ability to participate in the study.
   • Other hepatobiliary, renal, endocrine, urinary tract, muscular skeletal diseases which the investigator considers clinically significant.

6. History of splenectomy.

7. Known history of allergic or hypersensitivity to the components of IP.

8. Known history of serious adverse reaction, allergies or hypersensitivity related to vaccination.

9. Individual with history of bleeding diathesis or thrombocytopenia, or history of severe bleeding or bruising after intramuscular injection or venipuncture or is receiving an anticoagulant (Individual receiving low dose aspirin (less than 100mg/day) can be enrolled in judgement of investigator).

10. History of hereditary or idiopathic angioneurotic edema.

11. History of systemic urticaria within 5 years prior to administration of IP.

12. Individual with history of solid organ or bone marrow transplantation.

13. Individual who is suspected or with history of drug or alcohol abuse within 24 weeks prior to administration of IP.

14. History of licensed drug for COVID-19 prevention aside from COVID-19 vaccine within 52 weeks prior to administration of IP.

15. Use of immunosuppressive or chronic use of systemic steroids within 6 weeks prior to administration of IP (Topical steroids, nasal spray and inhalers are allowed).

    • Immunosuppressive: Azathioprine, Cyclosporine, Interferon, G-CSF, Tacrolimus, Everolimus, Sirolimus, Cyclophosphamide, 6-Mercaptopurine, Methotrexate, Rapamycin, Leflunomide, etc.
    • Chronic steroid: >10 mg/day prednisone equivalent for periods exceeding 14 days.

16. Individual who has administered other investigational product or device within 24 weeks prior to screening visit.

17. Individual who has received or planned to receive any other vaccines within 28 days prior and after the administration of IP (Flu vaccines can be administered up to 14 days prior to the date of IP administration).

18. Receipt of immunoglobulin or blood-derived products within 12 weeks prior to administration of IP.

19. Individual with scheduled surgery throughout the study period.

20. Pregnant or lactating women.

21. Individual directly related to the investigator and meets the following:

    • Personnel relationship or subordinate-superior relationship (employees of the investigator's department, staffs of this trial).
    • Students or researchers in the immediate department of the school to which the investigator belongs (e.g., medical university).

22. Individual who is unfit for this study for any other reason in judgement of investigator.