Rapid Development and Implementation of a Remote ECG-monitored Prospective Randomized Clinical Trial During a Pandemic: Hydroxychloroquine Prophylaxis in COVID-19 Household Contacts

Inclusion Criteria: * exposure to a COVID-19-infected individual in the same household within five days of diagnosis; * age \>18 years; * ability to give informed consent to participate in a clinical study; * ability to swallow oral medications; * access to a smartphone Exclusion Criteria: * allergy or intolerance to hydroxychloroquine (PlaquenilR); * weight less than 85 pounds; * eye disease affecting the retina; * severe kidney or liver disease; * G6PD-deficiency; * porphyria; * long QTc EKG abnormality or family history of this; * other major EKG abnormalities; * taking medications that can affect the QT interval including flecainide, amiodarone, digoxin, procainamide, propafenone, sotalol, quinidine, dofetilide, levofloxacin, ciprofloxacin, azithromycin, erythromycin, amitriptyline, doxepin, desipramine, imipramine, fluoxetine, sertraline, venlafaxine, quetiapine, haloperidol, droperidol, thioridazine, ziprasidone, furosemide, sumatriptan or zolmitriptan, cisapride, arsenic, dolasetron, or methadone; * current pregnancy; * current hospitalization; * symptomatic with fever or cough; * lack of access to a smartphone