As far as I know, the biggest impact right now seem to be: anti-clotting medication, steroids, turning the patient on his belly and avoiding intubation for as long as possible.
Health authorities didn't change recommendations on masks and dexamethasone due to twitter lobbying; they changed them because evidence emerged that they were safe and and least somewhat effective.
That said, I was really highlighting a recent example of how poor communication is, and how fast opinion can shift.
I'm sorry, does this address the comment at all? There was indeed, this spring, real scientific debate over the potential efficacy of hydroxychloroquine. But the raging Twitter wars over it did not constitute that debate.
I was asked if there's consensus regarding the effectiveness of HCQ. Currently, there is not. Not long ago, medical professionals were recommending it and there was, at least publicly, a consensus of sorts based on the positive results of early studies.
I then pointed out how fast consensus shifted from 'this stuff is awesome' to 'this stuff is stupid' because I believe it's relevant for anyone trying to formulate their own opinion about how solid that consensus really is.
The twitter wars and the general terrible communication online is a totally separate topic, and the one I was originally commenting on because /u/gbrown seemed to have a more positive outlook than I do on the subject.
At any given time there are thousands and thousands of unproven drugs under development or being evaluated for new applications. There are even many possible covid treatments being evaluated without similar controversy, because no-one with a large audience has suggested self-medication.
Hopefully the hydroxychloroquine thing is a one-off, and public figures will be more careful in future about public promotion of unapproved drugs. It would be extremely dangerous, and damaging to legitimate scientific investigation, if this sort of thing becomes common.
Similar case that springs to mind is the chap who had to infect himself to prove that stomach ulcers were caused by bacteria.
https://www.nobelprize.org/prizes/medicine/2005/press-releas...
Lyn Margulis did not and will not ever have that pleasure, because, like Rosalind Franklin, (a) she was female, and (b) she's now dead.
General rule: controversial theories, in a vacuum, are fine.
Promoting controversial theories in a manner likely to lead people to die (hydroxycloroquine self-medication, bleach-drinking, deliberate self-infection): not fine.
Twitter and Youtube are full of people promoting all sorts of nonsense, and also legitimate unorthodox theories (there is a difference; there's a huge gap between, say, "the earth is flat" and "dark matter isn't a thing") without any trouble. It's when you get into the realm of health advice that is likely to injure people that there's a problem.
I would assume that this incredibly smart scientist (for all her HIV and 9/11 bonkers and disgusting lunacy) would not be using Twitter as the medium for her scientific discussions.
I'm fascinated by how especially conspiracy theory people equate fighting on Reddit/Twitter/YouTube/… with real scientific debate.