None

None

participants will be excluded from participation in the study if any of the following criteria are met at screening: 1. positive pregnancy test either at screening or just prior to the first vaccine administration. 2. participants who is breastfeeding or planning on breastfeeding from the time of the first vaccination through 60 days after the last vaccination. 3. has any medical disease or condition that, in the opinion of the site pi or appropriate sub-investigator, precludes study participation. 4. acute or chronic gastrointestinal conditions such as crohn's, ulcerative colitis, gastritis, proctitis, ibs, or any other inflammatory bowel disease. 5. currently taking histamine-2 (h2) blocker, proton pump inhibitor (ppi), promotility agent, or any chronic antacids. 6. presence of self-reported or medically documented significant medical or psychiatric condition(s). 7. significant cardiovascular disease (e.g., congestive heart failure, cardiomyopathy, ischemic heart disease), uncontrolled hypertension, history of myocarditis or pericarditis as an adult, myocardial infarction (mi) within past 6 months, coronary artery bypass surgery or stent placement, or uncontrolled cardiac arrhythmia. 8. neurological or neurodevelopmental conditions (e.g., history of migraines in the past 5 years, epilepsy, stroke, seizures in the last 3 years, encephalopathy, focal neurologic deficits, guillain-barré syndrome, encephalomyelitis, transverse myelitis, stroke or transient ischemic attack, multiple sclerosis, parkinson's disease, amyotrophic lateral sclerosis, creutzfeldt-jakob disease, or alzheimer's disease). exclusion criteria participants will be excluded from participation in the study if any of the following criteria are met at screening: 1. positive pregnancy test either at screening or just prior to the first vaccine administration. 2. participants who is breastfeeding or planning on breastfeeding from the time of the first vaccination through 60 days after the last vaccination. 3. has any medical disease or condition that, in the opinion of the site pi or appropriate sub-investigator, precludes study participation. 4. acute or chronic gastrointestinal conditions such as crohn's, ulcerative colitis, gastritis, proctitis, ibs, or any other inflammatory bowel disease. 5. currently taking histamine-2 (h2) blocker, proton pump inhibitor (ppi), promotility agent, or any chronic antacids. 6. presence of self-reported or medically documented significant medical or psychiatric condition(s). 7. significant cardiovascular disease (e.g., congestive heart failure, cardiomyopathy, ischemic heart disease), uncontrolled hypertension, history of myocarditis or pericarditis as an adult, myocardial infarction (mi) within past 6 months, coronary artery bypass surgery or stent placement, or uncontrolled cardiac arrhythmia. 8. neurological or neurodevelopmental conditions (e.g., history of migraines in the past 5 years, epilepsy, stroke, seizures in the last 3 years, encephalopathy, focal neurologic deficits, guillain-barré syndrome, encephalomyelitis, transverse myelitis, stroke or transient ischemic attack, multiple sclerosis, parkinson's disease, amyotrophic lateral sclerosis, creutzfeldt-jakob disease, or alzheimer's disease). 9. ongoing malignancy or recent diagnosis of malignancy in the last five years excluding basal cell and squamous cell carcinoma of the skin, which are allowed. 10. active autoimmune disease or any history of autoimmune disease determined by hx or lab/physical examination. 11. individuals at high risk for severe covid-19, including those with any of the following risk factors: 1. t2dm 2. asthma 3. respiratory conditions (including emphysema or copd) 4. tobacco use (vaping, smoking, chew) within 1 year 12. chronic kidney disease, estimated glomerular filtration rate (egfr) <60 ml/min/1.73m^2. 13. immunocompromised individuals with known or suspected immunodeficiency, as determined by medical history or lab/physical examination. 14. acute illness, as determined by the site pi or appropriate sub-investigator, with or without fever [oral temperature >/= 38.0 degrees celsius (100.4 degrees fahrenheit)] within 72 hours prior to each vaccination. 15. history of hepatitis b, hepatitis c, or human immunodeficiency virus (hiv). 16. participation in another investigational study involving any investigational product within 60 days, or 5 half-lives, whichever is longer, before the first vaccine administration. 17. participation in another clinical trial with an investigational agent that will be received during the study-reporting period. 18. has a history of hypersensitivity or severe allergic reaction (e.g., anaphylaxis, generalized urticaria, angioedema, other significant reaction) to any previous licensed or unlicensed vaccines. 19. chronic use (more than 14 continuous days) or anticipated use within the next 6 months of any medications that may be associated with impaired immune responsiveness. including, but not limited to the following excluded drugs: systemic or inhaled corticosteroids, allergy injections, immunoglobulin, interferon, immunomodulators, cytotoxic drugs, or other similar or toxic drugs during the preceding 6-month period prior to vaccine administration (day 1). the use of low dose topical, ophthalmic, otic, and intranasal steroid preparations will be permitted. 20. anticipating the need for immunosuppressive treatment within the next 6 months. 21. receipt of immunoglobulin and/or any blood or blood products within the 4 months before the first vaccine administration or at any time during the study. 22. blood dyscrasias or significant disorder of coagulation, based on history or abnormal laboratory results. 23. chronic liver disease, including fatty liver. 24. has a history of alcohol abuse or other recreational drug (excluding cannabis) use within 6 months before the first vaccine administration. 25. received or plans to receive a licensed, live vaccine within 4 weeks before or after each vaccination. 26. received or plans to receive a licensed, inactivated vaccine within 2 weeks before or after each vaccination. 27. receipt of any other sars-cov-2, mers, sars-cov-1 or other experimental coronavirus vaccine at any time prior to or during the study. 28. close contact of anyone known to have covid-19 infection within 30 days prior to vaccine administration. 29. confirmed or suspected positive covid-19 test results via diagnostic or antibody test. 30. current treatment with investigational agents for prophylaxis of covid-19. 31. current use of any prescription or over-the-counter medications within 7 days prior to vaccination, unless approved by the investigator or necessary to manage a chronic condition. 32. plans to travel outside the participating country from enrollment through 28 days after the second vaccination. 33. healthcare worker at high risk of contracting sars-cov-2 34. reside in a skilled nursing home, have a requirement for skilled nursing care, and/or non-ambulatory. 35. medical or psychiatric condition including recent (with the past year) or active suicidal ideation/behavior or abnormality, self-reported or medically documented, that may increase the risk of study participation or make the participant inappropriate for the study based on the investigator's judgement.

participants will be excluded from participation in the study if any of the following criteria are met at screening: 1. positive pregnancy test either at screening or just prior to the first vaccine administration. 2. participants who is breastfeeding or planning on breastfeeding from the time of the first vaccination through 60 days after the last vaccination. 3. has any medical disease or condition that, in the opinion of the site pi or appropriate sub-investigator, precludes study participation. 4. acute or chronic gastrointestinal conditions such as crohn's, ulcerative colitis, gastritis, proctitis, ibs, or any other inflammatory bowel disease. 5. currently taking histamine-2 (h2) blocker, proton pump inhibitor (ppi), promotility agent, or any chronic antacids. 6. presence of self-reported or medically documented significant medical or psychiatric condition(s). 7. significant cardiovascular disease (e.g., congestive heart failure, cardiomyopathy, ischemic heart disease), uncontrolled hypertension, history of myocarditis or pericarditis as an adult, myocardial infarction (mi) within past 6 months, coronary artery bypass surgery or stent placement, or uncontrolled cardiac arrhythmia. 8. neurological or neurodevelopmental conditions (e.g., history of migraines in the past 5 years, epilepsy, stroke, seizures in the last 3 years, encephalopathy, focal neurologic deficits, guillain-barré syndrome, encephalomyelitis, transverse myelitis, stroke or transient ischemic attack, multiple sclerosis, parkinson's disease, amyotrophic lateral sclerosis, creutzfeldt-jakob disease, or alzheimer's disease). exclusion criteria participants will be excluded from participation in the study if any of the following criteria are met at screening: 1. positive pregnancy test either at screening or just prior to the first vaccine administration. 2. participants who is breastfeeding or planning on breastfeeding from the time of the first vaccination through 60 days after the last vaccination. 3. has any medical disease or condition that, in the opinion of the site pi or appropriate sub-investigator, precludes study participation. 4. acute or chronic gastrointestinal conditions such as crohn's, ulcerative colitis, gastritis, proctitis, ibs, or any other inflammatory bowel disease. 5. currently taking histamine-2 (h2) blocker, proton pump inhibitor (ppi), promotility agent, or any chronic antacids. 6. presence of self-reported or medically documented significant medical or psychiatric condition(s). 7. significant cardiovascular disease (e.g., congestive heart failure, cardiomyopathy, ischemic heart disease), uncontrolled hypertension, history of myocarditis or pericarditis as an adult, myocardial infarction (mi) within past 6 months, coronary artery bypass surgery or stent placement, or uncontrolled cardiac arrhythmia. 8. neurological or neurodevelopmental conditions (e.g., history of migraines in the past 5 years, epilepsy, stroke, seizures in the last 3 years, encephalopathy, focal neurologic deficits, guillain-barré syndrome, encephalomyelitis, transverse myelitis, stroke or transient ischemic attack, multiple sclerosis, parkinson's disease, amyotrophic lateral sclerosis, creutzfeldt-jakob disease, or alzheimer's disease). 9. ongoing malignancy or recent diagnosis of malignancy in the last five years excluding basal cell and squamous cell carcinoma of the skin, which are allowed. 10. active autoimmune disease or any history of autoimmune disease determined by hx or lab/physical examination. 11. individuals at high risk for severe covid-19, including those with any of the following risk factors: 1. t2dm 2. asthma 3. respiratory conditions (including emphysema or copd) 4. tobacco use (vaping, smoking, chew) within 1 year 12. chronic kidney disease, estimated glomerular filtration rate (egfr) <60 ml/min/1.73m^2. 13. immunocompromised individuals with known or suspected immunodeficiency, as determined by medical history or lab/physical examination. 14. acute illness, as determined by the site pi or appropriate sub-investigator, with or without fever [oral temperature >/= 38.0 degrees celsius (100.4 degrees fahrenheit)] within 72 hours prior to each vaccination. 15. history of hepatitis b, hepatitis c, or human immunodeficiency virus (hiv). 16. participation in another investigational study involving any investigational product within 60 days, or 5 half-lives, whichever is longer, before the first vaccine administration. 17. participation in another clinical trial with an investigational agent that will be received during the study-reporting period. 18. has a history of hypersensitivity or severe allergic reaction (e.g., anaphylaxis, generalized urticaria, angioedema, other significant reaction) to any previous licensed or unlicensed vaccines. 19. chronic use (more than 14 continuous days) or anticipated use within the next 6 months of any medications that may be associated with impaired immune responsiveness. including, but not limited to the following excluded drugs: systemic or inhaled corticosteroids, allergy injections, immunoglobulin, interferon, immunomodulators, cytotoxic drugs, or other similar or toxic drugs during the preceding 6-month period prior to vaccine administration (day 1). the use of low dose topical, ophthalmic, otic, and intranasal steroid preparations will be permitted. 20. anticipating the need for immunosuppressive treatment within the next 6 months. 21. receipt of immunoglobulin and/or any blood or blood products within the 4 months before the first vaccine administration or at any time during the study. 22. blood dyscrasias or significant disorder of coagulation, based on history or abnormal laboratory results. 23. chronic liver disease, including fatty liver. 24. has a history of alcohol abuse or other recreational drug (excluding cannabis) use within 6 months before the first vaccine administration. 25. received or plans to receive a licensed, live vaccine within 4 weeks before or after each vaccination. 26. received or plans to receive a licensed, inactivated vaccine within 2 weeks before or after each vaccination. 27. receipt of any other sars-cov-2, mers, sars-cov-1 or other experimental coronavirus vaccine at any time prior to or during the study. 28. close contact of anyone known to have covid-19 infection within 30 days prior to vaccine administration. 29. confirmed or suspected positive covid-19 test results via diagnostic or antibody test. 30. current treatment with investigational agents for prophylaxis of covid-19. 31. current use of any prescription or over-the-counter medications within 7 days prior to vaccination, unless approved by the investigator or necessary to manage a chronic condition. 32. plans to travel outside the participating country from enrollment through 28 days after the second vaccination. 33. healthcare worker at high risk of contracting sars-cov-2 34. reside in a skilled nursing home, have a requirement for skilled nursing care, and/or non-ambulatory. 35. medical or psychiatric condition including recent (with the past year) or active suicidal ideation/behavior or abnormality, self-reported or medically documented, that may increase the risk of study participation or make the participant inappropriate for the study based on the investigator's judgement.