At what point does a body of evidence become massive enough to count as proof? When has a question been answered enough times that it can be put to rest?

When it comes to the safety and effectiveness of vaccines, it sometimes seems as though public health advocates must constantly roll the burden of proof toward a mountaintop that never comes into view.

The latest salvo against vaccinations came courtesy of Robert Kennedy Jr. and Robert De Niro. At a joint appearance this week, Kennedy offered $100,000 to anyone who could turn up a study showing that it is safe to administer vaccines to children and pregnant women, with a specific call out to concerns about mercury. De Niro was there to lend his endorsement and a patina of Oscar-winning gravitas.

Both men have an unreliable history when it comes to their views about vaccinations. Kennedy’s reference to mercury alludes to thimerosal, a preservative once used in vaccines, which he has long maintained can lead to autism. (It doesn’t.) A meeting earlier this year between then President-elect Donald Trump (who has hair-raising views of his own about vaccines) and Kennedy caused grave concern within the medical community, myself included. Kennedy claimed Trump asked him to helm a commission on vaccine safety (even though the United States already has a vaccine safety commission), but it has yet to materialize.

De Niro came under fire for endorsing a film that purports a link between vaccinations and autism, though instead of mercury, it blames the measles/mumps/rubella (MMR) vaccine...

...https://www.washingtonpost.com/news/to-your-health/wp/2017/02/17/the-evidence-for-vaccine-safety-is-abundant-that-will-be-100000-please/?utm_term=.e0aa1f7c5dd8