Why is this doctor combining the two pills? Hydroxychloroquine is the one being prescribed.
Chloroquine was used in the initial study and was found to have an antiviral effect, without zinc, against SARS-CoV. Chinese researchers substituted HCQ as it was available to them. There is a third quinoline, quinacrine (or mepacrine in other countries, trade name, Atabrine), which although unavailable in US can be made by compounding pharmacists. It is feared more dangerous than the others.