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.