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:

• Provide written informed consent prior to initiation of any study procedures
• Able and willing (in the investigator's opinion) to comply with all study requirements
• Are men or non-pregnant women aged 18 years or older at enrollment
• Are in good health*

*As defined by absence of clinically significant medical conditions defined by the CDC as increasing risk for severe corona virus disease-19 (COVID-19) (see exclusion criteria), or other acute or chronic medical conditions determined by medical history, physical examination (PE), 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). Any prescription change that is due to change of health care provider, insurance company, etc., or done for financial reasons, and in the same class of medication, will not be considered a deviation of this inclusion criterion. Any change in prescription medication due to improvement of a disease outcome, as determined by the participating site PI or appropriate sub- investigator, will not be considered a deviation of this inclusion criterion. Subjects may be on chronic or as needed (prn) medications if, in the opinion of the participating site PI or appropriate sub-investigator, they pose no additional risk to subject safety or assessment of reactogenicity and immunogenicity, and do not indicate a worsening of medical diagnosis/condition. Similarly, medication changes in the 60 days prior to enrollment as well as subsequent to enrollment and study vaccination are acceptable provided the change was not precipitated by deterioration in the chronic medical condition, and there is no anticipated additional risk to the subject or interference with the evaluation of responses to study vaccination.

• Agree to refrain from blood donation during the course of the study
• Plan to remain living in the area for the duration of the study
• 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 50 and = / / = 110 pounds

• Screening laboratory evaluations are within acceptable ranges at the site where the leukapheresis procedure will be performed
• Negative urine or serum pregnancy test at screening and on the day of the leukapheresis procedure for women of childbearing potential
• Adequate bilateral antecubital venous access
• No use of blood thinners, aspirin, or nonsteroidal anti-inflammatory drugs (NSAIDs) at least 5 days before the leukapheresis procedure

Exclusion Criteria

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

• History of prior confirmed (PCR or antigen test positive) COVID-19 less than 112 days prior to enrollment.
• Positive for anti-nucleoprotein SARS-CoV-2 specific antibody by enzyme-linked immunosorbent assay (ELISA) and had the history of upper respiratory illness (URI) compatible with COVID-19 during the 112 days prior to enrollment (seropositivity without a history of URI during the 112 days prior to enrollment will be considered remotely infected persons eligi