I've been pondering over how we got to this point, with nonsensical opposition to COVID vaccines and mitigation measures. This is an older article, but it's still valid, IMO.
How Republican Coronavirus Vaccine Opposition Got to This Point - The New York Times (nytimes.com)
As I understand it, historically, anti-vax attitudes were very much on the fringes of both the left and the right. On the left, we had naturopathic "medicine" that eschewed modern practices. On the right it was primarily fundamentalist religious (and erroneous) interpretations of scripture that fed anti-vax mindsets.
With the onset of the COVID-19 pandemic, the mainstream on both sides of the political spectrum seemed to be onboard with sensible public health policies. But then, the right found that they could create a wedge issue that they could (cynically and irresponsibly) exploit. Trump, wanting all the credit for any progress against COVID, started undermining the experts who knew what they were talking about while playing footsie with the lunatic fringe. Right-wing parties in other countries - including my own - took note.
The rest is sad history.