On November 19, 2025, RFK Jr. changed a section on the CDC website titled “Vaccines and Autism.” The website now states, “The claim ‘vaccines do not cause autism’ is not an evidence-based claim because studies have not ruled out the possibility that infant vaccines cause autism.”
You can never prove never.
However, 24 studies performed in 7 countries on 3 continents involving thousands of children and costing tens of millions of dollars have all found the same thing. Children who have received the MMR vaccine were not at greater risk of developing autism than those who didn’t receive it. Researchers could have done a hundred studies, or a thousand studies, or a million studies but that still wouldn’t have proven that it couldn’t happen.
You can never prove never. However, given the scientific data, it’s fair to state that vaccine doesn’t cause autism. The same can be said (for the same reasons) of thimerosal and alumninum salts.
You can’t prove I’ve never been to Witchita, Kansas, you can only show a series of pictures of buildings in Witchita with me not standing next to them. We can’t “prove” that RFK, Jr. is wrong. But he is. Vaccines are probably the best studied of all environmental influences, have never shown to cause autism. We can say that with certainty.