Here are the 4 most promising COVID-19 drugs according to WHO Updated : May 11, 2020 06:32 PM IST All in all, more than 20 COVID-19 studies in China used chloroquine or hydroxychloroquine, WHO notes, but their results have been hard to come by. Researchers in France have published a study in which they treated 20 COVID-19 patients with hydroxychloroquine. Chinese researchers who report treating more than 100 patients with chloroquine touted its benefits in a letter in BioScience. Published : March 23, 2020 06:31 PM IST