This study is to assess the safety, reactogenicity and immunogenicity of a SK SARS-CoV-2 recombinant protein subunit vaccine (NBP2001) in healthy adults.

This is a first-in-human, Phase I, randomized, placebo-controlled, observer-blinded study to assess the safety, reactogenicity and immunogenicity of a SK SARS-CoV-2 recombinant protein subunit vaccine (NBP2001) in healthy adults.

A total of 50 healthy adults between 19 and 55 years of age will be enrolled and block-randomized in a 4:1 ratio to receive 2 doses of either one NBP2001 formulation (Test group 1 or 2) or placebo saline (Placebo group).

Over the study period, participants will commonly attend 10 planned visits. Telephone calls will be made 7 days after each vaccination (Day 7+3 after Visit 2 and Visit 4). However, sentinel participants will be required to return at Day 7(+ 3 days) after 1st vaccination for rigorous safety assessment.

Study vaccination will comprise 2 intramuscular injections of saline placebo, or a 30 or 50μg dose of NBP2001 in an injection volume of approximately 0.5mL. The study vaccines will be injected preferably into the deltoid muscle of the upper arm at a 28-day interval.

Halting rules based on reactogenicity and safety outcomes are defined, and enrollment and study vaccination may be paused during the study if any halting rules are met.

Inclusion Criteria:

Age

1. Participant must be 19 to 55 years of age inclusive, at the time of signing the informed consent.

   Type of Participant and Disease Characteristics

2. Participants who are healthy as determined by medical evaluation including medical history, physical examination, clinical laboratory tests, and medical judgement of the investigator

3. Participants who are able to attend all scheduled visits and comply with all study procedures.

   Weight

4. Body mass index (BMI) within the range 18-30 kg/m2 at screening (inclusive)

   Sex and Contraceptive/Barrier Requirements

5. Female participants of childbearing potential must agree to be heterosexually inactive, or agree to consistently use at least one acceptable method of contraception from at least 21 days prior to the 1st study vaccination to 8 weeks after the last study vaccination

6. Female participants with a negative urine or serum pregnancy test at screening

   Informed Consent

7. Capable of giving signed informed consent which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in this protocol.

Exclusion Criteria:

Medical Conditions

1. Any clinically significant respiratory symptoms (e.g. cough, sore throat), febrile illness (tympanic temperature >38°C), or acute illness within 72 hours prior to the 1st study vaccination. A prospective participant should not be included until 72 hours after the condition has resolved.

2. History of virologically-confirmed COVID-19 disease, or definite or suspected exposure to anyone known to have SARS-CoV-2 infection

3. History of virologically-confirmed SARS or MERS disease

4. History of congenital, hereditary, acquired immunodeficiency, or autoimmune disease

5. Any positive test results for hepatitis B, C, or HIV at screening

6. History of bleeding disorder or thrombocytopenia which is contraindicating intramuscular vaccination in the investigator's opinion

7. History of hypersensitivity and severe allergic reaction (e.g. anaphylaxis, Guillain-Barre syndrome) to any vaccines or components of the study intervention

8. History of malignancy within 5 years prior to the 1st study vaccination

9. Significant chronic illness that, in the opinion of the investigator, might increase risk of severe COVID-19, or interfere with the evaluation of the study objectives (e.g. asthma, chronic pulmonary disease, cardiovascular disease, chronic liver disease, diabetes mellitus, uncontrolled hypertension, renal disorders)

10. History of, or planned surgery under general anesthesia from 1 year prior to the 1st study vaccination through the study period

11. Any other conditions which, in the opinion of the investigator, might interfere with the evaluation of the study objectives (e.g. neurologic or psychiatric conditions)

12. Female participants who are pregnant or breastfeeding

13. Current smokers or a recent smoking history within 12 weeks prior to the 1st study vaccination. Occasional smokers who smoke up to 10 cigarettes per month may be allowed to participate at the investigator's discretion

    Prior/Concomitant therapy

14. Receipt of any medications or vaccinations intended to prevent COVID-19.

15. Receipt of any vaccine within 4 weeks prior to the 1st study vaccination or planned receipt of any vaccine from enrollment through 28 days after the last study vaccination (Visit 7), except for influenza vaccination, which may be received at least 2 weeks prior to the 1st study vaccination. This exception includes monovalent pandemic influenza vaccines and multivalent influenza vaccines

16. Receipt of immunoglobulins and/or any blood or blood products within 12 weeks prior to the 1st study vaccination

17. Chronic use (more than 2 consecutive weeks) of immunosuppressive therapy, such as anti-cancer chemotherapy or radiation therapy; or long-term systemic corticosteroid therapy (≥10mg prednisone/day or equivalent for more than 2 consecutive weeks) within 12 weeks prior to the 1st vaccination. The use of topical and nasal glucocorticoids will be permitted.

    Prior/Concurrent Clinical Study Experience

18. Participation in another clinical study involving study intervention within 6 months prior to the 1st study vaccination, or concurrent, planned participation in another clinical study with study intervention during this study period.

    Other Exclusions

19. Investigators, or study staff who are directly involved in the conduct of this study or supervised by the investigator, and their respective family members.

20. Healthcare worker or emergency response personnel in an occupation with a high risk of exposure to SARS-CoV-2