Inclusion Criteria:

• Positive laboratory test for COVID-19 based on local laboratory standard.
• Age greater than or equal to 18 years of age.
• At least one symptom of coronavirus as utilized by the CDC within 24 hours of enrollment (https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/symptoms.html). [Currently those symptoms include: Fever or chills, cough, shortness of breath or difficulty breathing, fatigue, muscle or body aches, headache, new loss of taste or smell, sore throat, congestion or running nose, nausea or vomiting, or diarrhea].

Exclusion Criteria:

• Age less than 18 years.
• •  
• Randomization > 7 days of symptom onset.
• Currently taking an angiotensin converting enzyme inhibitor (ACEi) or Angiotensin receptor blocker (ARB).
• Prior reaction or intolerance to an ARB or ACE inhibitor, including but not limited to angioedema.
• Pregnant or breastfeeding women.
• Women able to have children not currently taking a protocol allowed version of contraception: intrauterine device, Depo-formulation of hormonal contraception (e.g. medroxyprogesterone acetate / Depo- Provera), subcutaneous contraceptive (e.g. Nexplanon), daily oral contraceptives with verbalized commitment to taking daily throughout the study, condom use or abstinence during the study. All women of child bearing age enrolled in this fashion will be informed of the teratogenic risks.
• Patient reported history or electronic medical record history of kidney disease, defined as:
  • Any history of dialysis;
  • History of chronic kidney disease stage IV;
  • Estimated Glomerular Filtration Rate (eGFR) of < 30ml/min/1.73 m^2 (must be have been measured within 1 month of enrollment);
  • Other kidney disease that in the opinion of the investigator, would affect losartan clearance.
• Patient reported dehydration and significantly decreased urine output in the past 72 hours.
• Most recent systolic blood pressure prior to enrollment < 110 mmHg.
• Patient reported history or electronic medical record history of severe liver disease, defined as:
  • Cirrhosis;
  • History of hepatitis B or C;
  • Other liver disease that in the opinion of the investigator, would affect losartan clearance;
  • Documented AST or ALT > 3 times the upper limit of normal within 3 months of randomization (if available in electronic medical record).
• Potassium > 5.0 mmol/L (must have been measured within 1 month) of enrollment.
• Concurrent treatment with aliskiren.
• Inability to obtain informed consent.
• Enrollment in another blinded randomized clinical trial for COVID.