A Phase 2, Double-Blind, Multi-Center, Randomized, Placebo-Controlled, Dose-Ranging Trial to Determine the Safety, Immunogenicity and Efficacy of an Adenoviral-Vector Based Vaccine Expressing Severe Acute Respiratory Syndrome (SARS-CoV-2) and dsRNA Adjuvant Administered Orally

Number of Participants Who Experienced a Solicited Symptom of Reactogenicity

Time Frame: Up to 7 days after Dose 1 (Days 1 to 8) and Dose 2 (Days 29 to 36)

Solicited symptoms of reactogenicity were predefined systemic signs and symptoms of reactogenicity for which the participant was specifically questioned, and which were noted by the participant in their daily Solicited Symptom Diary for 7 days after each vaccination, including: * fever (any temperature 100°F or higher) * headache * myalgia (muscle pain) * abdominal pain * anorexia (defined and not eating) * nausea * vomiting * diarrhea * malaise/fatigue

Severity of Solicited Symptoms of Reactogenicity

Time Frame: Up to 7 days after Dose 1 (Days 1 to 8) and Dose 2 (Days 29 to 36)

Solicited symptoms of reactogenicity were predefined systemic signs and symptoms of reactogenicity for which the participant was specifically questioned, and which were noted by the participant in their daily Solicited Symptom Diary for 7 days after each vaccination, including: * fever (any temperature 100°F or higher) * headache * myalgia (muscle pain) * abdominal pain * anorexia (defined and not eating) * nausea * vomiting * diarrhea * malaise/fatigue Participants were instructed to rate solicited symptoms of reactogenicity that were collected in their Solicited Symptom Diary with the below grades, against pre-defined criteria as noted in the protocol: * Grade 1 - Mild * Grade 2 - Moderate * Grade 3 - Severe * Grade 4 - Life Threatening Participants with multiple solicited symptoms were only counted once, the highest severity of which was used.

Number of Participants Who Experienced an Unsolicited Treatment-emergent Adverse Event (TEAE) During the Active Treatment Period

Time Frame: Day 1 to Day 57

A TEAE was any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention, occurring after first dose of study drug. A serious TEAE was any TEAE that met any of the following criteria: * Resulted in death. * Was life-threatening. * Required inpatient hospitalization or prolongation of existing hospitalization. * Resulted in persistent or significant disability/incapacity. * Was a congenital anomaly/birth defect. * Was a suspected transmission of any infectious agent via a medicinal product. * Was a significant medical event, as judged by the investigator.

Severity of Unsolicited TEAEs During the Active Treatment Period

Time Frame: Day 1 to Day 57

All unsolicited TEAEs during the active treatment period were assessed by the investigator using the below scale: * Mild: Events that required minimal or no treatment and did not interfere with the participant's daily activities. * Moderate: Events that resulted in a low level of inconvenience or concern with the therapeutic measures. Moderate events may have caused some interference with functioning. * Severe: Events that interrupted a participant's usual daily activity and may have required systemic drug therapy or other treatment. Severe events were usually incapacitating. * Life Threatening: Any adverse drug experience that placed the participant, in the view of the investigator, at immediate risk of death from the reaction as it occurred. Participants with multiple TEAEs during the active treatment period were only counted once, the highest severity of which was used.

Number of Participants Who Experienced a Medically Attended Adverse Event (MAAE) During the Active Treatment Period

Time Frame: Day 1 to Day 57

MAAEs were defined as TEAEs with medically-attended visits including hospital, emergency room, urgent care clinic, or other visits to or from medical personnel for any reason. Routine study visits were not considered medically-attended visits. New onset of chronic illness/diseases (NOCI) and adverse events of special interest (AESIs) were collected as part of the MAAEs. As defined in the protocol, adverse events for potential immune-mediated medical conditions as well as events associated with thrombosis and thrombocytopenia were considered AESIs.

Severity of MAAEs During the Active Treatment Period

Time Frame: Day 1 to Day 57

All MAAEs during the active treatment period were assessed by the investigator using the below scale: * Mild: Events that required minimal or no treatment and did not interfere with the participant's daily activities. * Moderate: Events that resulted in a low level of inconvenience or concern with the therapeutic measures. Moderate events may have caused some interference with functioning. * Severe: Events that interrupted a participant's usual daily activity and may have required systemic drug therapy or other treatment. Severe events were usually incapacitating. * Life Threatening: Any adverse drug experience that placed the participant, in the view of the investigator, at immediate risk of death from the reaction as it occurred. Participants with multiple MAAEs during the active treatment period were only counted once, the highest severity of which was used.