1) Known G6PD deficiency 2) Contra-indication to hydroxychloroquine, azithromycin or Vitamin C: allergy to study interventions, epilepsy, serious hearing or visual problems, history of severe depression, calcium oxalate stones, advanced liver disease, pregnancy or lactating 3) Already receiving chloroquine, azithromycin, more than 3 grams Vitamin C daily or an experimental antiviral 4) History of fever (e.g. night sweats, chills) and/or acute respiratory infection (e.g. cough, shortness of breath, sore throat) of more than 7 days’ duration. Note, if study numbers not quickly reached, the investigators may decide to include those with symptoms of longer than 7 days 5) Calculated creatinine clearance of less than 30 mL/minute 6) Baseline ECG showing: QTc greater than or equal to (>=) 470 for males, QTc greater than or equal to (>=) 480 for females 7) Receipt of a drug known to increase QTc: quetiapine, amiodarone, sotalol

1) Known G6PD deficiency 2) Contra-indication to hydroxychloroquine, azithromycin or Vitamin C: allergy to study interventions, epilepsy, serious hearing or visual problems, history of severe depression, calcium oxalate stones, advanced liver disease, pregnancy or lactating 3) Already receiving chloroquine, azithromycin, more than 3 grams Vitamin C daily or an experimental antiviral 4) History of fever (e.g. night sweats, chills) and/or acute respiratory infection (e.g. cough, shortness of breath, sore throat) of more than 7 days’ duration. Note, if study numbers not quickly reached, the investigators may decide to include those with symptoms of longer than 7 days 5) Calculated creatinine clearance of less than 30 mL/minute 6) Baseline ECG showing: QTc greater than or equal to (>=) 470 for males, QTc greater than or equal to (>=) 480 for females 7) Receipt of a drug known to increase QTc: quetiapine, amiodarone, sotalol