One of the techniques of propaganda is called "The Big Lie." You just keep repeating the same lie over and over again, and eventually people believe it because they remember having heard it before.

The disturbed person who keeps claiming he knows the clinical trial results has been proven time and time again to be a liar. It's best to put him on ignore so that if you happen upon a lie before it's deleted, you don't waste 10 seconds of your life reading his lies.