It's odd that the author only traces the political aspect back to 2015, when climate change denial has been a political issue since the turn of the millennium: https://en.m.wikipedia.org/wiki/Climate_change_policy_of_the...
And I'd heard of the anti-vaxx movement in the mid-90's.
I'm sure the crunchy-granola antivaxers are still out there, but they were a fringe group and remain a fringe group. But for the GOP it's mainstream.
COVID's a little different from general anti-vax, being driven by a hoax narrative from the President combined with the perception of rushing a vaccine through (with the intention of having it be an October surprise for the election). That makes everybody nervous, on all sides of the spectrum.