Safety, Immunogenicity, and Efficacy of INO-4800 for COVID-19 in Adults at High Risk of SARS-CoV-2 Exposure

Key Inclusion Criteria:

- Working or residing in an environment with high risk of exposure to SARS-CoV-2 for
whom exposure may be relatively prolonged or for whom personal protective equipment
(PPE) may be inconsistently used, especially in confined settings.

- Phase 2 only: Screening laboratory results within normal limits for testing laboratory
or are deemed not clinically significant by the Investigator.

- Be post-menopausal or be surgically sterile or have a partner who is sterile or use
medically effective contraception with a failure rate of < 1% per year when used
consistently and correctly from Screening until 3 months following last dose (Phase 2)
or until last dose (Phase 3).

Key Exclusion Criteria:

- Acute febrile illness with temperature higher than or equal to 100.4°F (38.0°C) or
acute onset of upper or lower respiratory tract symptoms (e.g., cough, shortness of
breath, sore throat).

- Positive serologic or molecular (Reverse transcription polymerase chain reaction
(RT-PCR)) test for SARS-CoV-2 at Screening (this criterion applies to all Phase 2
participants and only applies after approximately 402 participants positive for
SARS-CoV-2 serologic test are randomized in the Phase 3 segment of the study).

- Pregnant or breastfeeding or intending to become pregnant or intending to father
children within the projected duration of the trial starting from the Screening visit
until 3 months following the last dose (Phase 2) or until last dose (Phase 3).

- Known history of uncontrolled HIV based on a CD4 count less than 200 cells per cubic
millimeter (/mm^3) or a detectable viral load within the past 3 months.

- Is currently participating or has participated in a study with an investigational
product within 30 days preceding Day 0.

- Previous or planned receipt of an investigational (including Emergency Use
Authorization (EUA) or local equivalent authorization) or licensed vaccine for
prevention or treatment of COVID-19, middle east respiratory syndrome (MERS), or
severe acute respiratory syndrome (SARS) (documented receipt of placebo in previous
trial would be permissible for trial eligibility).

- Respiratory diseases (e.g., asthma, chronic obstructive pulmonary disease) requiring
significant changes in therapy or hospitalization for worsening disease during the 6
weeks prior to enrolment.

- Immunosuppression as a result of underlying illness or treatment.

- Lack of acceptable sites available for ID injection and EP.

- Blood donation or transfusion within 1 month prior to Day 0.

- Reported alcohol or substance abuse or dependence, or illicit drug use (excluding
marijuana use).

- Any illness or condition that in the opinion of the investigator may affect the safety
of the participant or the evaluation of any study endpoint.