This is an open-label, dose-ranging trial to determine the safety and immunogenicity of an orally administered adenoviral-vector based vaccine (VXA-COV2-1) expressing a SARS-CoV-2 antigen and dsRNA adjuvant. Post screening activities, healthy adult volunteers aged 18 - 54 yrs old, inclusive, will be enrolled into the study. Participants will receive an oral dose of vaccine at Days 1 and a subject will also receive a second dose at Day 29; total study period will last ~ 2 months during the active phase, with a total 12 month safety follow-up period post last vaccination. Safety, reactogenicity and immunogenicity assessments will be performed at set times during the study active and follow-up periods. Subjects will be monitored for symptoms of COVID-19 throughout the duration of the study follow-up period.~Approximately 10 healthy male and female adult volunteers 18 to 54 years old who were enrolled in the main study will be included in a boost extension substudy for an additional 12 months from dosing for a total participation period of 24-25 months.
VXA-CoV2-1 is a non-replicating Ad5 vector adjuvanted oral tableted vaccine being developed to prevent COVID-19, the disease resulting from Severe Acute Respiratory Syndrome coronavirus (SARS-CoV-2) infection. The study is designed to evaluate the safety and immunogenicity of VXA-CoV2-1 vaccine with repeat dosing at multiple dose levels. Safety and immunogenicity will be evaluated for up to 12 months after the second dose of VXA-CoV2-1.