This is a First in Human, randomized, placebo-controlled Phase I/II trial to evaluate the safety and immunogenicity of the intradermal COVID-19 vaccine, EXG-5003 in healthy adults.

Inclusion Criteria:

• Has provided written consent for participation
• Age between 20 and 55
• Has a negative nucleic acid-based test result for SARS-CoV-2
• Has a negative antibody test result for SARS-CoV-2

Exclusion Criteria:

• Signs and symptoms consistent with COVID-19 upon screening
• History of COVID-19
• Presence of uncontrolled cardiovascular, hematologic, respiratory, hepatic, renal, gastrointestinal, or neuropsychiatric disease
• Presence of diabetes mellitus
• Presence of active autoimmune disease
• Positive for HBc, HCV or HIV antibody
• History of anaphylactic shock
• History of epilepsy
• Presence of active malignancy
• Presence of lung disease (e.g., COPD, asthma)
• Positive urine pregnancy test within 24 hours
• Pregnant, lactating, planned pregnancy of self (if female) or partner (if male) within 90 days after administration of the trial drug
• If female and premenopausal, not agreeable to contraception for 90 days after second administration of the trial drug
• If male, not agreeable to contraception for 90 days after second administration of the trial drug
• Presence of clinically relevant electrocardiogram or vital sign abnormality at screening
• Participated in a clinical trial of a drug or a medical device within 30 days or a biologic within 90 days
• Received any SARS-CoV-2 vaccine
• Received within 90 days, or is planning to receive during the study period, an immunoglobulin or blood product
• Received within 180 days, or is planning to receive during the study period, a biologic product with immunosuppressive properties
• Received for 14 days or more within 180 days, or is planning to receive during the study period, a corticosteroid
• Deemed ineligible for the study as determined by the principal investigator or a co-investigator