An Open Label Study in Adults to Test the Efficacy of Mitoquinone/Mitoquinol Mesylate to Prevent Severe Viral Illness

Inclusion Criteria: * All enrolled participants must meet the following criteria: * Age 18-65 years old. * Asymptomatic (no symptoms of viral infection) on study entry. * Exposure to a person with at least two new onset independent symptoms or signs (fever) of respiratory viral disease * High risk exposure without use of masks and physical distancing to suspected case of viral illness (based on established symptoms of viral illness) in the household within 3 days prior to study entry. Rationale: Antivirals are most efficacious when given as early as possible post exposure. * Ineligible for FDA approved alternative treatments to prevent progression to severe COVID-19 based on established criteria https://www.cdc.gov/coronavirus/2019-ncov/need-extra-precautions/people-with-medical-conditions.html or FDA approved alternative treatment cannot be obtained or not indicated (e.g. allergy). * Without established significant coronary artery/vascular disease, lung, stroke, kidney, liver, heart disease) based on history. * Adequate renal function. This is defined as absence of documented history of any kidney disease. Exclusion Criteria: * Participants who meet any of the following criteria at screening will be excluded from the study: 1. Use of Coenzyme Q10 or Vitamin E \< 120 days from enrollment 2. Women with variations in physiological functions due to hormones that may effect immune function and (taking hormones, pregnant, breastfeeding, on contraceptives). 3. Pregnant (based on history). 4. History of known gastrointestinal disease (such as gastroparesis) that may predispose patients to nausea. Gastrointestinal symptoms are the most common side effects of MitoQ. 5. History of auto-immune diseases 6. Chronic viral hepatitis 7. History of underlying cardiac arrhythmia 8. History of severe recent cardiac or pulmonary event 9. A history of a hypersensitivity reaction to any components of the study drug or structurally similar compounds including Coenzyme Q10 and idebenone 10. Unable to swallow tablets 11. Use of any investigational products within 28 days of study enrollment 12. Any other clinical condition or prior therapy that, in the opinion of the investigator, would make the patient unsuitable for the study or unable to comply with the study requirements. Such conditions may include, but are not limited to, current or recent history of severe, progressive, or uncontrolled renal, hepatic, hematological, gastrointestinal, endocrine, pulmonary, neurological, or cerebral disease 13. Participants who are eligible for FDA approved alternative treatments to prevent progression to severe COVID-19 based on established criteria https://www.cdc.gov/coronavirus/2019-ncov/need-extra-precautions/people-with-medical-conditions.html