Most people determine what they think is true or false in really unreliable, irrational ways. If you ask someone about anything, religion, politics, health, diet etc, their reasoning almost never makes sense.
Take a classic mistake in reasoning 'my grandma smoked and lived until 90 so I'm gonna smoke too.' So the person smokes, maybe dies a decade or two early, which is sad, but the effect of that bad reasoning doesn't have a significant impact on society as a whole.
During the pandemic though suddenly you need everyone to think rationally in order to protect society as a whole, in order for the system to work.
I have a few anti-vaxxer friends and I'd talk to them sometimes during the days of the pandemic (as in an actual discussion, not a fight, I know that wouldn't help). I tried to explain how to reliably determine when something is (likely) true vs false, but none of them ever managed to change their thinking. Even a rational anti-vax argument seemed to be beyond them. For example you could say something like 'I'll take the vaccine, but not yet because it's not gone through the proper testing' and okay, I disagree, but fair enough, that's rational. Instead I'd get theories about population control, immigration (somehow), microscopic tentacle monsters in the vaccine (yes, seriously) and so on.
As I say, they're my friends, so overall I consider them good, kind people, but I'm kind of convinced nowadays that some people just don't have the mental ability to reason properly and idk really what we should do about that because there are going to be occasions again where that's going to hurt others.