Are you talking about the Henry Ford study?
https://www.google.com/amp/s/news.yahoo.com/amphtml/hydroxychloroquine-the-drug-trump-cant-quit-180041001.html
It wasn’t double-blind or randomized and even the CEO admits it’s not definitive.
You’re going to need more than this to justify widespread use of HXQ when there are many other studies pointing in the opposite direction.
However, research into this and any other possible treatment should continue.