Plenty of people have commented on Clinton's semi-fainting spell yesterday, but here's some psychology. Some that hasn't been debunked. Yet, anyway. (Y'all know that pretty much the entire field is in a replication crisis, right?)
Anywho, Hillary Clinton has been the subject of weird conspiracy theories for decades. Back in April, I used math (yes, math!) to explain why this gave us permission to be lazy and pay no attention to questions about whether or not she would be indicted for X. The answer would always be no. And hey, look, she wasn't indicted.
But conspiracy theories sometimes have other relevance. Lately, conspiracy theories have focused on Clinton's health. Enter pneumonia, lung left. (Maybe right. I dunno). The conspiracy theories are far more elaborate than that, but merely by existing, they... prime people to focus more on such moments, overanalyze them, ask whether or not the pneumonia is symptomatic of something else, and so forth.
And even if voters don't necessarily believe the conspiracy theories, the press are forced to cover such stuff, thereby sacrificing attention that could have been paid to something else.
Will it matter? Probably not. For what it's worth, the prediction markets have Trump's chances up to 27%, if we can believe such minor movement. I don't take the numbers as being that precise.
What is mattering? Here's what I have to say at this point. I keep referencing Alan Abramowitz and his "Time for a Change" model. The Republicans have an advantage this year. Three-in-a-row is rare, and only happens with strong economic growth. Democrats have won two in a row, and economic growth is only tepid. Clinton's lead is dependent on Trump's weakness as a candidate. Trump has been subdued lately. Without Trump acting like Trump, Clinton's lead is slipping. That's just a guess, though. Could the pneumonia thing play into it? Maybe a tiny, tiny bit. Like, virus small.