I think a contributing factor is the general demographics of the parties. Conservative areas tend to rural and less densely populated compared to liberal areas that tend to be higher density populations. Rural communities are more "take care of yourself" and I thinks a lot of our inability to meet eye to eye comes from different base assumptions.
I feel like it's a case where you the stereotypes exist to backwards explain any outcome that you want.
Like NYC and Boston famously have a "fuck you, mind you own business" stereotype contrasted with a rural stereotype expectation of cooperating for the community.
I think the higher order bit is Repliblicans pushing an anti-institutional agenda more recently (including Trump saying bad things about historically conservative institutions like the FBI) which naturally lines up with an antivax agenda.
And, it's not anti-science for the sake of anti-science. It's part of an overall anti-establishment theme. The point of it is to sell people on the idea that they are under attack and only one party (man) is their savior. To do that, they have to cleave people away from reality. So, it's all mistrust built primarily on misinformation and conspiracy theories, whether it's Q or COVID.
And, voilà: with these grievances and fears so viciously stoked, you now have an army of programmed drones under your command who believe they're fighting an existential war for their freedom vs simply being asked to be a responsible member of society.
That's how you end up with people like this woman, who are closer to the center of the party than many people want to admit:
An interesting wrinkle to this is all the media personalities and Democrat politicians (including our current VP) that we’re staunchly opposed to the vaccine while Trump was still president.
Now that Biden is president, it is apparently a different vaccine (for both sides of the aisle)
What the current VP said during the previous administration was that she was not confident that the previous administration would base their recommendations on what scientists said rather than what is politically expedient, and that she would go with what the scientists said when it came to evaluating COVID measures.
What she actually said: “If Dr. Fauci, if the doctors tell us that we should take it, I’ll be the first in line to take it. Absolutely,” Harris said. “But if Donald Trump tells us to take it, I’m not taking it.”
And again, she is just one example among very very many.
Generally, when someone says "If X ... but if Y" they are talking about the cases X && !Y and !X && Y. For the X && Y case you need to look at other statements. In Harris' case her other statements are that she did not consider Trump a creditable source of COVID treatment information.
Harris is saying that if Dr. Fauci says to take it she would regardless of what Trump says, and that if Trump says to take it but Dr. Fauci does not she would not take it.
For example in the UK vaccination rates amongst Conservative and Labour voters are the same.
So why is there such disparity in the US between Biden voters and Trump voters when it comes to Covid-denialism, pseudo-cures, and antivaxxing?