COVID-19 PEP- High-risk Individuals in Long-term and Specialized Care - Canada

Inclusion Criteria: 1. Age over 40 with two or more high-risk comorbidities that have been found to confer a higher risk of mortality including but not limited to : chronic lung disease to include: Chronic obstructive lung disease, interstitial lung disease or diffuse parenchymal disease moderate to severe asthma * Cardiac conditions to include: recent myocardial infarction (within the last three months) or poorly controlled heart failure * severe obesity (body mass index \[BMI\] of 40 or higher) * Diabetes (type 1 or 2) * chronic kidney disease undergoing dialysis * liver cirrhosis OR Age over 60. 2. Patient/resident in an Institute (to include a rehabilitation, long term care facility, mental health facility or veteran's care) that provides bed-based care in shared semi-private or ward rooms (i.e. two or more to a room) with a patient with confirmed COVID-19 for at least 6 hours in the absence of contact and droplet precautions. 3. Exposure with a documented or suspected COVID-19 case or from a symptomatic ( defined as common symptoms of COVID-19 including but not limited to fever, lethargy, dry cough, shortness of breath) health care worker providing direct patient contact within 3 feet without a mask for \> 15min or any physical contact with the staff. Exposure may occur in single or shared bedrooms. Exposure may occur in a common dining or activity or sitting area. Any patient sharing a room or within 3 feet for \> 15min or any physical contact without a mask will be considered as a contact. Patients or staff are considered as infectious for 48hrs before any symptoms onset and until masked or cleared by 2 negative swabs. 4. No prior treatment with acetaminophen or NSAIDs or willing to stop present prescription of regular or PRN acetaminophen. 5. Informed consent (in person or by telephone/e-mail with SDM) Exclusion Criteria: 1. Greater than 96 hours since last exposure 2. Presence of fever (T\>37.8), new onset cough, or shortness of breath at enrollment 3. A baseline O2 saturation less than 90% (as measured by pulse oximetry) on room air 4. Screening ECG QTc interval greater than 500ms by either a 12 lead or 6 lead ECG. 5. Concomitant drug-drug interactions (Artemether, Dapsone, Lumefantrine or Mefloquine amiodarone, digoxin, dofetilide, flecainide, procainamide, sotalol, or propafenone levofloxacin, ciprofloxacin, moxifloxacin, azithromycin, clarithromycin, erythromycin, ketoconazole, or itraconazole methadone sumatriptan, or zolmitriptan systemic chemotherapy.) 6. Already on active palliative care measures (Palliative performance score (PPS) less than 30%) 7. Hypersensitivity reaction to chloroquine, hydroxychloroquine or aminoquinolines 8. History of retinal disease due to previous use of 4-aminoquinoline 9. Prior documented and known at enrollment, retinal eye disease or maculopathy including but not limited to diabetic retinopathy, retinal detachment, retinitis pigmentosa or macular degeneration 10. Known glucose-6 phosphate dehydrogenase (G6PD) deficiency 11. Known Porphyria 12. Acute delirium 13. Inability to swallow oral study drug/placebo (even after crushed in the same manner as regular prescribed medications) 14. Diagnosis of immunodeficiency (e.g. HIV, transplantation) or receiving systemic steroid therapy (\>10mg prednisone daily or equivalent) or any other form of immunosuppressive therapy prior to trial treatment 15. Women who are pregnant or breastfeeding