Interestingly, anti-vaxerism used to be a subculture on the left. I used to go to a Unitarian church, some time before the pandemic. There was no lack of anti-vaxers there.
There were even anti-vaxers in the 1950s. I can remember my parents talking about someone or another and my mom chiming in with, "she's one of those people who won't get their kids vaccinated. She's dumb, dumb!"
Everybody seems to have forgotten that Trump was originally very pro-vaccine. Operation Warp Speed and all that. But he fell in line behind his followers. That’s the kind of "leader" he is.