A Ph 2 Trial With an Oral Tableted COVID-19 Vaccine

Part 1: This is an open-label, dose-ranging phase of the study to determine the safety and immunogenicity of an orally administered adenoviral-vector based vaccine (VXA-COV2-1.1-S) expressing a SARS-CoV-2 antigen and dsRNA adjuvant. Post screening activities, healthy adult volunteers, either naïve or prior vaccinated with an mRNA COVID-19 vaccine, aged 18 - 55 yrs old, and then 56 - 75 yrs old, will be enrolled into the study in 8 subgroups. Participants will receive either a low or a high dose of an oral tableted vaccine at Days 1 and Day 29. The 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. An independent data monitoring committee (IDMC) will provide safety oversight through the duration of the trial. Safety and immunogenicity data will inform on the dose selection for Part 2. Part 2: This will be a placebo-controlled phase with the vaccine dose level selected from Part 1. Subjects will receive two doses of vaccine or placebo at Days 1 and 29. Subjects will be followed as in Part 1 for safety and immunogenicity. They will also be followed for 6 months for efficacy.