This is an interesting instance in which to measure that. It's hard to tease out the cause-and-effect here. You get the same thing with politicians: are they saying something to convince their constituents, or are they saying it because their constituents are already saying it and they know it's what they want to hear?

My suspicion is that it's some of each, and I'd bet that the numbers in red districts will rise some, but not a lot. Proportional to the ~2 million Fox News viewers, out of ~80 million people who voted Republican last time. Not that all Fox News viewers will rush out to be vaccinated, but that [say] 25% of them will and influence an equivalent number of non-viewers.

Pulling those numbers out of my ass, of course.