I'm starting to wonder if perhaps the best thing we could do for the public health is to start a project analogous to Apollo, but for autism: massively fund studies to nail down what causes autism (and, ideally, how to cure it) within ten years.
My reasoning here has very little to do with autism itself, though finding the cause and (if possible) a cure would certainly be nice. My reasoning is that even though most antivaxxers don't find the no-proof argument ("there is literally no reason to believe that vaccines cause autism") to be compelling, most of them should find a counter-proof argument ("vaccines don't cause autism, because this other thing causes it") satisfying enough.
The nice version of the consequences of this is that most antivaxxers should finally accept that they have been duped, which should boost the voluntary vaccination rate. The not-so-nice version is that with a counter-proof in hand, it should be possible to take those parents who still believe, deem them incompetent to decide on this issue, and administer the vaccinations anyway. Either way, the vaccination rate goes back up.