Not in an antiviral context, and certainly not for SARS-CoV-2.
Yes, which is why all of the studies keep saying that it's too dangerous to use as treatment for covid-19.
It may be too toxic, it may not cause a noticeable effect, but currently it is a big question mark.
[1] Except now we know (and we always thought this) that it won't save their life; it'll increase their risk of death.
As has been mentioned elsewhere, we'll have to answer soon, but power speaks with a forked tongue in this case. Too many anecdotal observations to be comfortable in the very loud politicization of the science.
The Lancet study and others cannot be accepted a conclusion to the safety & efficacy of early/prophylactic use. Let's wait for and encourage some proper, specific studies.