Chimpanzee Adenovirus and Self-Amplifying mRNA Prime-Boost Prophylactic Vaccines Against SARS-CoV-2 in Healthy Adults

Inclusion Criteria:

Subjects eligible to participate in this trial must meet all of the following inclusion criteria:

1. Provide written informed consent prior to initiation of any study procedures
2. Able and willing (in the investigator's opinion) to comply with all study requirements
3. Are males or non-pregnant females aged 18 years or older at enrollment

4. Are in good health*

   *As defined by absence of clinically significant medical conditions defined by The Centers for Disease Control and Prevention (CDC) as increasing risk for severe coronavirus disease 2019 (COVID-19) disease (see exclusion criteria), or other acute or chronic medical conditions determined by medical history, physical examination, screening laboratory test results, and/or clinical assessment of the investigator that are either listed as exclusion criteria below or in the opinion of the investigator would increase risk for study participation or affect the assessment of the safety of subjects. Chronic medical conditions should be stable for the last 60 days (no hospitalizations, emergency room or urgent care for condition, or invasive medical procedures). This includes no change in chronic prescription medications in the 60 days prior to enrollment

5. Agree to refrain from blood donation during the course of the study
6. Plan to remain living in the area for the duration of the study

7. Women of childbearing potential (WOCBP)* must plan to avoid pregnancy for at least 60 days after the last study vaccination and be willing to use an adequate method of contraception** consistently for 30 days prior to first study vaccine and for at least 60 days after the last study vaccine.

   *Not sterilized via bilateral oophorectomy, tubal ligation/salpingectomy, hysterectomy, or successful Essure (R) placement (permanent, non-surgical, non-hormonal sterilization with documented radiological confirmation test at least 90 days after the procedure); still menstruating; or < 1 year has passed since the last menses if menopausal

   **Acceptable methods of birth control include the following: oral contraceptives, injection hormonal contraceptive, implant hormonal contraceptive, hormonal patch, intrauterine device, spermicidal products and barrier methods (such as cervical sponge, diaphragm, or condom with spermicide), abstinence, monogamous with a vasectomized partner, non-male sexual relationship

8. Women of childbearing potential must have a negative urine or serum pregnancy test within 24 hours prior to each study vaccination

9. Vital signs within acceptable ranges:

   • Heart rate > 50 and < 100 beats per minute
   • Systolic blood pressure = / < 140 millimeters of mercury (mmHg)
   • Diastolic blood pressure = / < 90 mmHg
   • Temperature < 37.8°C (100.0°F)
10. Clinical screening lab evaluations (white blood cell (WBC), hemoglobin (HgB), platelets (PLT), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total bilirubin (T Bili), creatine kinase, (CK), serum creatinine (Cr) and prothrombin time (PT)/partial thromboplastin time (PTT)) are within acceptable normal reference ranges at the clinical lab being used, with the exception that ALT, AST, ALP, and creatinine values that are below the reference range will not be exclusionary as these values below reference range are clinically insignificant. Any other screening lab value outside the reference range that is thought to be clinically insignificant by a site investigator must be discussed with the DMID Medical Officer prior to enrollment
11. Must agree to genetic testing and storage of samples for secondary research

Exclusion Criteria:

Subjects eligible to participate in this trial must not meet any of the following exclusion criteria:

1. History of prior confirmed coronavirus disease 2019 (COVID-19)
2. Positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by enzyme-linked immunosorbent assay (ELISA) or by nasal swab polymerase chain reaction (PCR) at screening.

3. Presence of medical comorbidities that would place the subject at increased risk for severe COVID-19*

   *chronic kidney disease, chronic lung disease (including moderate-to-severe asthma), chronic heart disease (heart failure, coronary artery disease or cardiomyopathies), cerebrovascular disease, body mass index(BMI) > / = 30 kg/m2, diabetes mellitus, chronic liver disease, sickle cell disease

4. Increased risk of occupational exposure to SARS-CoV-2 (healthcare workers and emergency response personnel)
5. Prior receipt of an investigational SARS-CoV-2 vaccine (including under emergency use authorization [EUA]), approved or investigational adenovirus vectored vaccines, approved or investigational vaccines with an LNP component, or any other approved or investigational vaccine likely to impact the interpretation of the trial data
6. On current treatment or prevention agents with activity against SARS-CoV-2
7. Current smoking or vaping
8. History of smoking or vaping in prior year
9. Breastfeeding, pregnant, or planning to become pregnant during the course of the study.
10. Participation in another research study involving receipt of an investigational product in the 60 days preceding enrolment or planned use during the study period
11. Receipt or planned receipt of any live, attenuated vaccine within 28 days before or after study vaccination
12. Receipt or planned receipt of any subunit or killed vaccine within 14 days before or after vaccination
13. Administration of immunoglobulins and/or any blood products within the three months preceding the planned administration of first study vaccination or at any time during the study
14. Any confirmed or suspected immunosuppressive or immunodeficient state, including HIV infection, asplenia, recurrent, severe infections and chronic (more than 14 continuous days) immunosuppressant medication within the past 6 months (inhaled, ophthalmic and topical steroids are allowed)
15. History of allergic disease or reactions likely to be exacerbated by any component of the vaccine, including urticaria, respiratory difficulty or abdominal pain (or any immediate allergic reaction of any severity to polysorbate due to potential cross-reactive hypersensitivity with the polyethylene glycol component of the vaccine)
16. Any history of hereditary angioedema, acquired angioedema, or idiopathic angioedema
17. Any history of anaphylaxis, including but not limited to reaction to vaccination
18. Any history of severe allergic drug reaction
19. History of cancer (except basal cell carcinoma of the skin and cervical carcinoma in situ)
20. History of serious ongoing, unstable psychiatric condition that in the opinion of the investigator would interfere with study participation
21. Seizure in the past 3 years or treatment for seizure disorder in the past 3 years
22. Bleeding disorder (e.g., Factor deficiency, coagulopathy or platelet disorder), or prior history of significant bleeding or bruising following IM injections or venipuncture
23. Suspected or known current alcohol abuse. Suspected or known drug abuse in the 5 years preceding enrollment
24. Seropositive for HIV, hepatitis B surface antigen (HBsAg) or seropositive for hepatitis C virus (antibodies to HCV)

25. Have an acute illness* within 72 hours prior to study vaccination

    *An acute illness which is nearly resolved with only minor residual symptoms remaining is allowable if, in the opinion of the site PI or appropriate sub-investigator, the residual symptoms will not interfere with the ability to assess safety parameters as required by the protocol

26. Any other condition that in the opinion of the investigator would pose a health risk to the participant if enrolled or could interfere with evaluation of the trial vaccine or interpretation of study results