As I've commented before (probably in vain), "no evidence" does not mean "no immunity." It just means what it says, at this point we have no evidence--either way (those supposed case reports are not evidence). I cannot conceive of a way this early for there to be any evidence, so it should be no surprise that we have no evidence. It doesn't mean anything more than that.
What the Stanford "study" shows is what can happen when the normal processes of science are short-circuited in an emergency that produces nonstop public/media attention: you get a lot of junk science. When investigators are not rushed, they are more likely to craft better-designed studies. When IRB approval is not rushed or bypassed, problems with methodology are more likely to be noticed. When researchers wait for normal peer review and don't put out press releases or "preprints," the first product to reach the public is likely to be much better.
What the Stanford "study" shows is what can happen when the normal processes of science are short-circuited in an emergency that produces nonstop public/media attention: you get a lot of junk science. When investigators are not rushed, they are more likely to craft better-designed studies. When IRB approval is not rushed or bypassed, problems with methodology are more likely to be noticed. When researchers wait for normal peer review and don't put out press releases or "preprints," the first product to reach the public is likely to be much better.