[hhw]

The side effects have also been known for a long time, which is why dosage is carefully monitored in Lupus patients and blindness is an anticipated side effect.

My understanding is that another side effect of HCQ is that it extends the QT cycle, and given the duress COVID-19 puts on the heart, there is not an insignificant risk of cardiak arrest. There may not be as much data to show this as conclusively or prevalently as some might like, but the underlying mechanisms are well enough understood that it would be reckless to continue prescribing HCQ until it had been sufficiently demonstrated that the benefits outweighed this risk.

There really wasn't sufficient reason to think that HCQ would work in the first place, based on any understanding of how the drugs works. It was just the original, now discredited paper from China that opened up the floodgates in the first place. The antiviral properties are far too weak and would require far too high (dangerous) concentrations in vivo, far in excess of what's commonly prescribed for other purposes, to match the earlier in vitro results. If there's any benefit to HCQ, it would be from immunosupression. But dexamethasone serves that purpose much more effectively, and has shown much better results so it doesn't make much sense to continue exploring HCQ.