In 2010, vaccines weren’t really a divisive topic that was politically aligned. That’s come later as the right started to take an interest, and then accelerated via COVID and disagreements about the various approaches implemented to manage the epidemic by the government that caused controversy - masks, lockdowns, and vaccines.
Which is to say, it’s not so much the liberal/left causing a problem here - I think they’re just holding the ground they’ve always had - that vaccines are generally safe and generally a good thing.
I think before it was mostly a nonpartisan topic, but after COVID it was kind of a thing where if you're on the left, you'd be on the side of science and thus vehemently defend vaccines while assuming the other side is a bunch of antivaxxers
and then the other side doesn't want to be associated with the other and thus ...
it should've never been politicized in the first place
Which is to say, it’s not so much the liberal/left causing a problem here - I think they’re just holding the ground they’ve always had - that vaccines are generally safe and generally a good thing.