Though the causes of autism have not yet been determined, some things, like vaccines, have been exonerated. It is much more likely that some of the thousands of industrial pollutants, endocrine disrupters, carcinogens, etc, are to blame. It will take more time to find which ones.
But anti-vaxxers don't care about the facts anymore, if they ever did. Their egos are so dependent on dumb conspiracy theories, they would emotionally collapse if they admitted they were wrong.