the presence of any of the following will mean participants are ineligible: 1. known covid-19 positive test at baseline (if available) 2. symptomatic for possible covid-19 at baseline 3. known hypersensitivity reaction to hcq, chloroquine or 4-aminoquinolines 4. known retinal disease 5. known porphyria 6. known chronic kidney disease (ckd; egfr\<30ml/min) 7. known epilepsy 8. known heart failure or conduction problems 9. known significant liver disease (gilbert's syndrome is permitted) 10. known glucose-6-phosphate dehydrogenase (g6pd) deficiency 11. currently taking any of the following contraindicated medications: 1. digoxin 2. chloroquine 3. halofantrine 4. amiodarone 5. moxifloxacin 6. cyclosporin 7. mefloquine 8. praziquantel 9. ciprofloxacin 10. clarithromycin 11. prochlorperazine 12. fluconazole 12. currently taking hydroxychloroquine or having a clinical indication for taking hydroxychloroquine 13. currently breastfeeding 14. unable to be followed-up during the trial 15. current or future involvement in the active treatment phase of other interventional research studies (excluding observational/non-interventional studies) before study follow-up visit 16. not able to use or have access to a modern phone device/web-based technology 17. any other clinical reason which may preclude entry in the opinion of the investigator

the presence of any of the following will mean participants are ineligible: 1. known covid-19 positive test at baseline (if available) 2. symptomatic for possible covid-19 at baseline 3. known hypersensitivity reaction to hcq, chloroquine or 4-aminoquinolines 4. known retinal disease 5. known porphyria 6. known chronic kidney disease (ckd; egfr\<30ml/min) 7. known epilepsy 8. known heart failure or conduction problems 9. known significant liver disease (gilbert's syndrome is permitted) 10. known glucose-6-phosphate dehydrogenase (g6pd) deficiency 11. currently taking any of the following contraindicated medications: 1. digoxin 2. chloroquine 3. halofantrine 4. amiodarone 5. moxifloxacin 6. cyclosporin 7. mefloquine 8. praziquantel 9. ciprofloxacin 10. clarithromycin 11. prochlorperazine 12. fluconazole 12. currently taking hydroxychloroquine or having a clinical indication for taking hydroxychloroquine 13. currently breastfeeding 14. unable to be followed-up during the trial 15. current or future involvement in the active treatment phase of other interventional research studies (excluding observational/non-interventional studies) before study follow-up visit 16. not able to use or have access to a modern phone device/web-based technology 17. any other clinical reason which may preclude entry in the opinion of the investigator

the presence of any of the following will mean participants are ineligible: known covid-19 positive test at baseline (if available) symptomatic for possible covid-19 at baseline known hypersensitivity reaction to hcq, chloroquine or 4-aminoquinolines known retinal disease known porphyria known chronic kidney disease (ckd; egfr<30ml/min) known epilepsy known heart failure or conduction problems known significant liver disease (gilbert's syndrome is permitted) known glucose-6-phosphate dehydrogenase (g6pd) deficiency currently taking any of the following contraindicated medications: digoxin chloroquine halofantrine amiodarone moxifloxacin cyclosporin mefloquine praziquantel ciprofloxacin clarithromycin prochlorperazine fluconazole currently taking hydroxychloroquine or having a clinical indication for taking hydroxychloroquine currently breastfeeding unable to be followed-up during the trial current or future involvement in the active treatment phase of other interventional research studies (excluding observational/non-interventional studies) before study follow-up visit not able to use or have access to a modern phone device/web-based technology any other clinical reason which may preclude entry in the opinion of the investigator

the presence of any of the following will mean participants are ineligible: known covid-19 positive test at baseline (if available) symptomatic for possible covid-19 at baseline known hypersensitivity reaction to hcq, chloroquine or 4-aminoquinolines known retinal disease known porphyria known chronic kidney disease (ckd; egfr<30ml/min) known epilepsy known heart failure or conduction problems known significant liver disease (gilbert's syndrome is permitted) known glucose-6-phosphate dehydrogenase (g6pd) deficiency currently taking any of the following contraindicated medications: digoxin chloroquine halofantrine amiodarone moxifloxacin cyclosporin mefloquine praziquantel ciprofloxacin clarithromycin prochlorperazine fluconazole currently taking hydroxychloroquine or having a clinical indication for taking hydroxychloroquine currently breastfeeding unable to be followed-up during the trial current or future involvement in the active treatment phase of other interventional research studies (excluding observational/non-interventional studies) before study follow-up visit not able to use or have access to a modern phone device/web-based technology any other clinical reason which may preclude entry in the opinion of the investigator

the presence of any of the following will mean participants are ineligible: 1. known covid-19 positive test at baseline (if available) 2. symptomatic for possible covid-19 at baseline 3. known hypersensitivity reaction to hcq, chloroquine or 4-aminoquinolines 4. known retinal disease 5. known porphyria 6. known chronic kidney disease (ckd; egfr<30ml/min) 7. known epilepsy 8. known heart failure or conduction problems 9. known significant liver disease (gilbert's syndrome is permitted) 10. known glucose-6-phosphate dehydrogenase (g6pd) deficiency 11. currently taking any of the following contraindicated medications: 1. digoxin 2. chloroquine 3. halofantrine 4. amiodarone 5. moxifloxacin 6. cyclosporin 7. mefloquine 8. praziquantel 9. ciprofloxacin 10. clarithromycin 11. prochlorperazine 12. fluconazole 12. currently taking hydroxychloroquine or having a clinical indication for taking hydroxychloroquine 13. currently breastfeeding 14. unable to be followed-up during the trial 15. current or future involvement in the active treatment phase of other interventional research studies (excluding observational/non-interventional studies) before study follow-up visit 16. not able to use or have access to a modern phone device/web-based technology 17. any other clinical reason which may preclude entry in the opinion of the investigator

the presence of any of the following will mean participants are ineligible: 1. known covid-19 positive test at baseline (if available) 2. symptomatic for possible covid-19 at baseline 3. known hypersensitivity reaction to hcq, chloroquine or 4-aminoquinolines 4. known retinal disease 5. known porphyria 6. known chronic kidney disease (ckd; egfr<30ml/min) 7. known epilepsy 8. known heart failure or conduction problems 9. known significant liver disease (gilbert's syndrome is permitted) 10. known glucose-6-phosphate dehydrogenase (g6pd) deficiency 11. currently taking any of the following contraindicated medications: 1. digoxin 2. chloroquine 3. halofantrine 4. amiodarone 5. moxifloxacin 6. cyclosporin 7. mefloquine 8. praziquantel 9. ciprofloxacin 10. clarithromycin 11. prochlorperazine 12. fluconazole 12. currently taking hydroxychloroquine or having a clinical indication for taking hydroxychloroquine 13. currently breastfeeding 14. unable to be followed-up during the trial 15. current or future involvement in the active treatment phase of other interventional research studies (excluding observational/non-interventional studies) before study follow-up visit 16. not able to use or have access to a modern phone device/web-based technology 17. any other clinical reason which may preclude entry in the opinion of the investigator