Evaluation of the RD-X19 Treatment Device in Individuals With Mild to Moderate COVID-19

Inclusion Criteria 1. Positive for SARS-CoV-2 as detected using an FDA authorized SARS-CoV-2 antigen test at or within 24 hours of the screening visit. 2. COVID-19 signs and symptoms within 72 hours from symptom onset, including at least two moderate\* or greater symptoms from: cough, sore throat, nasal congestion, headache, unexplained chills and/or sweats, myalgia, fatigue, nausea (with or without vomiting). o Alternatively, subjects with the presence of at least one moderate symptom and either a) a fever with an oral temperature of at least 100.5° F or b) shortness of breath/difficulty breathing on exertion (e.g., walking, going up and down stairs) are also eligible for enrollment. 3. BMI \<40 4. Provides written informed consent prior to initiation of any study procedures. 5. Be able to understand and agrees to comply with planned study procedures and be available for all study visits. 6. Agrees to the collection of saliva, nasopharyngeal, and venous blood specimens per protocol. 7. Males or females, 18 to 65 years of age, inclusive. 8. No uncontrolled disease process(es) based on patient reported medical history (chronic or acute), other than direct COVID-19 signs and symptoms. 9. No physical or mental conditions or attributes at the time of screening, which in the opinion of the PI, will prevent full adherence to, and completion of, the protocol. * Symptom scoring is independent from the classification of COVID-19 disease severity at baseline. Guidance to study subjects for grading of signs and symptoms will be based on definitions used for the grading of TEAEs: * None (Grade 0): Not present * Mild (Grade 1): Symptoms that are usually transient and may require only minimal or no palliative or specific therapeutic intervention and generally do not interfere with the subject's usual activities of daily living. * Moderate (Grade 2): Symptoms that are usually alleviated with palliative or specific therapeutic intervention. The symptoms interfere with usual activities of daily living causing discomfort but pose no significant or permanent risk of harm to the study subject. * Severe (Grade 3): Events interrupt usual activities of daily living, or significantly effect clinical status, or may require intensive therapeutic intervention. Severe events are usually incapacitating. Exclusion Criteria 1. Positive urine pregnancy test at screening or females who intend to become pregnant during the study. 2. COVID-19 signs associated with severe respiratory distress or imminent serious medical outcomes.\^\^ \^\^Potential Study Subjects Presenting with any of the following should be referred for immediate medical care and are not eligible for the study * Fever \> 104° F * Cough with sputum production * Rales and/or rhonchi * Difficulty breathing with respiratory distress defined by a respiratory rate ≥30 per minute, heart rate ≥125 per minute, SpO2 ≤93% on room air at sea level or PaO2/FiO2 \<300. * Persistent pain or pressure in the chest * Confusion 3. Any medical disease or condition that, in the opinion of the site Principal Investigator (PI) or appropriate sub-investigator, precludes study participation. 4. Reports a recent positive test result (within the past 6 months) for hepatitis A, hepatitis B or, hepatitis C virus antibody, or HIV-1 antibodies at screening. 5. Has a history of alcohol abuse or other recreational drug (excluding cannabis) use within 1 month of Study Day 1. 6. Currently enrolled in or plans to participate in another clinical trial with a therapeutic investigational agent (e.g., monoclonal antibody, oral protease inhibitor) that will be received during the study period. 7. History of systemic antiviral therapies (e.g., remdesivir) within the past 30 days. 8. History of oral or parenteral corticosteroid use within the past 30 days. Active use of nasal or inhalable steroids is also exclusionary. Topical steroids are not exclusionary. 9. Has a history of hypersensitivity or severe allergic reaction (e.g., anaphylaxis, generalized urticaria, angioedema, other significant reaction) to sun exposure. 10. Currently undergoing photodynamic therapy (PDT) or photochemotherapy (PUVA) for an unrelated disease or condition that utilizes photosensitizing drugs including but not limited to 5-aminolevulinic acid, Methyl-5-aminolevulinic acid, porfimer sodium, methoxsalen (8-methoxypsoralen), 5-methoxypsoralen, trioxsalen. 11. Has any oral abnormality (e.g., ulcer, oral candidiasis, oral mucositis, gingivitis) that in the opinion of the investigator would interfere with device use and evaluation. 12. Any intra-oral body piercings that cannot be removed and remain removed for the duration of the study. Metal orthodontia is permitted as braces will be covered by the device mouthpiece. 13. Any individual without teeth or with a dental malformation that precludes directed use of the device as intended.