My personal belief is that there a lot of people who believe stupid things out there (and it's all only amplified by the news and social media), and for anti vaxxers especially I don't think an authority figure saying 'You have to get the measles vaccine!' is going to help much, unfortunate as it is. :(
We managed to cut the smoking rate pretty dramatically, including in about half over the last decade. Public policy is not ineffective, we just need competent people to wield it.
Also smoking smells and has other negative externalities, which doesn't hurt.