Chloroquine and hyrdorchloroquine have been in use for decades (70 years for chloroquine!) with millions taking them daily and a very well known safety profile. It was already FDA approved, could have been used by any doctor for COVID as an off-label treatment already. Everything about CQ/HCQ has been ridiculously politicized to the point that the facts have become very hard to find.
In fact, given the huge number of people taking them for lupus and other diseases (a significant fraction of a percent of the population, having autoimmune disorders and poor health and thus at greater COVID risk), we've basically had a biased but ultra-informative experiemnt already: What percentage of them got covid and what severity, as compared to general population, and compared to other comparable populations (autoimmune that isn't treated by CQ/HCQ)? It's not perfect, but it would have been very informative. CDC has this info. No ethical issues about it.
In fact, given the huge number of people taking them for lupus and other diseases (a significant fraction of a percent of the population, having autoimmune disorders and poor health and thus at greater COVID risk), we've basically had a biased but ultra-informative experiemnt already: What percentage of them got covid and what severity, as compared to general population, and compared to other comparable populations (autoimmune that isn't treated by CQ/HCQ)? It's not perfect, but it would have been very informative. CDC has this info. No ethical issues about it.