Inclusion Criteria:  Is between 18 and 80 years of age. Is within 72 hours from onset of symptoms consistent with COVID-19 at time of study screening. Has at least 2 of the following: fever (oral temperature ≥38°C), cough, shortness of breath, chest x-ray changes consistent with COVID-19 at time of screening. Has a laboratory-confirmed SARS-CoV-2 infection as determined by FDA-approved rapid diagnostic (e.g., PCR) assay. Has a score of ≤ 2 on the 8-category National Institute of Allergy and Infectious Diseases (NIAID) ordinal rating scale at time of screening. [Protocol Appendix 22.2] Agrees to the collection of blood and urine samples, nasopharyngeal (NP) swabs, and non-invasive oxygen monitoring (via pulse oximeter) as required by study protocol. Patient or their legally authorized representative is willing and able to provide written informed consent prior to performing study procedures. Understands and agrees to comply with planned study procedures. Women of childbearing potential must agree to either abstinence or use of at least one primary form of contraception not including hormonal contraception from the time of screening through Day 29 following randomization. All subjects of childbearing potential, including males with partners of childbearing potential, must use highly effective methods of birth control defined as those, alone or in combination, that result in a low failure rate (i.e., less than 1% per year) when used consistently and correctly [Protocol Appendix 22.3]. Abstinence is NOT an acceptable method of contraception UNLESS it is the subject's normal practice  Exclusion Criteria:  Is currently hospitalized. Prior history of, or considered to be at risk for, agranulocytosis, nephropathy, liver disease or interstitial pneumonia. Current or historic positive human immunodeficiency virus (HIV) test. Presence of organ transplant. Receipt of cancer chemotherapy or immunomodulatory drugs including but not limited to biologics such as anti-CD20, anti-TNF, anti-IL6; alkylating agents (e.g., cyclophosphamide), antimetabolites (e.g., azathioprine), or chronic corticosteroid use equivalent to prednisone >10 gm/day, during the 2 months prior to screening. Confirmed positive for influenza at screening. Confirmed positive for respiratory syncytial virus (RSV) at screening. Pregnant or breastfeeding. Current use of, or known allergy to cysteamine, bucillamine or penicillamine (e.g., for Wilson's disease, rheumatoid arthritis). Current participation in any other clinical trial of an experimental treatment for any indication including COVID-19. Receipt of any experimental treatment for COVID-19 (herbal, homeopathic, over the counter, off-label, compassionate use, or clinical trial related) within the 30 days prior to screening. Receipt of any medication for treatment or prevention of COVID-19 being used pursuant to an Emergency Use Authorization (e.g., vaccine) prior to or during study participation