This following article(not peer reviewed yet, in pre-print) is a
multicenter, randomized, placebo-controlled, double-blind, parallel-group trial. It provided a loading dose of hydroxychloroquine (HCQ) 600 mg twice on day 1 followed by 400 mg daily for 29 days or placebo. The outcome was a confirmed or suspected COVID-19 infection. 1360 people participated.
The regimen was safe, no differences in the safety profiles of HCQ and placebo were detected.
Regarding the COVID-19 infection outcome, there was a slight difference in favor of HCQ, however, it was not statistically significant. It would take a larger study to be able to determine if the difference was significative.