OK then what about all the travellers who've regularly used quinine analogues visiting malaria infested regions? Were any major qualms raised then when these drugs were used against malaria? No. Yes they do have side effects like cardiac arrhythmias and ECGs can be monitored so those with dodgy tickers could be advised to take favilavir or another antiviral like remdesavir if availiable. Or use lower doses. To achieve micromolar concentrations intracellular only 50 - 100 mg hydroxychloroquine daily would be necessary over a period of a week or so, together with 30 mg Zn citrate as supplement in case of Zn deficiency. I have contacted the BBC about this under their Q and answer session and hope to ask their reporters why the NHS and government are doing precisely nothing about anti viral treatment here in the face of good evidence that it has been highly effective elsewhere (China, S Korea, Japan). Let's see if it is effective in Italy now it has at long last been approved there. Nothing to stop Amazon distributing it on humanitarian grounds.
The issue is whether the anti-malarial doses are as high as the necessary anti-viral doses.
Malarial prophylactic dose:
Usual Adult Dose for Malaria Prophylaxis
Suppression: 400 mg (310 mg base) orally on the same day every week
From : https://www.drugs.com/dosage/h…e_for_Malaria_Prophylaxis
That is 60mg per day
For malarial treatment it is 400mg or 800mg per day.
Anti-viral dose used in trial:
All patients in Marseille center were proposed oral
hydroxychloroquine sulfate 200 mg, three times per day during ten day
That is 600mg per day.
See the difference? This is a drug which has known side effects on heart. Malaria also has known effects (it kills) so you balance that when treating the disease.
Not that we should not use it, just that risk/benefit needs to be considered at the 10X higher dosage.
You suggest it may be protective (or something) at much lower dosages. I'm not sure on what evidence? But I'm all for more trials to find out! I agree, at lower doses it is pretty safe (though even so not completely).