This is false, because many careful studies have compared populations, otherwise identical, that differed in one particular -- one received vaccinations, the other didn't. The outcome is that there is no difference between them.

Think about this in everyday terms -- consider the financial advantage, the scientific prestige, that would accrue to someone who located such a link. Wealth, fame, the unrequited love of women. But even though this issue has been studied repeatedly, no one has been able to show a scientific correlation between vaccines and autism.

Andrew Wakefield pretended to show a link, but his motives are now obvious -- he received thousands of dollars in consulting fees from a group of lawyers trying cases related to this issue, and he sought a patent on a vaccine of his own design, a vaccine that would have enriched him if there was such a link. These facts call his objectivity into question. And examination of his "scientific" work shows a repeated pattern of fraud and deception.

I suggest that you think like a scientist. Scientists don't say what you have, in essence: "if it hasn't been disproven, that's an argument in its favor." Scientists only count positive evidence as support for a hypothesis, and there is none for this issue. Indeed all the studies come to the same conclusion -- there is no link between vaccines and autism.

If autism was something we had genetic or biological tests for, this would be a valid concern. Presently, however, we don't have a biomarker for autism - the studies determine whether children have autism by looking at their symptoms. If vaccines did cause a significant increase in symptoms, we should expect it to move some number of individuals from "undetectable" to "detectable" and we'd see that in the numbers.

There is the narrow possibility, which may well have been looked at but hasn't been discussed, that vaccines could make autism worse only when it is significant to begin with, so nothing is crossing the threshold between not-quite-autism to autism, but I don't think we have any more evidence cause us to expect that relative to the simpler hypothesis that vaccines have roughly the same impact at any degree of autism: none.