I DO think it is note-worthy that children with heavy metal poisoning have symptoms almost identical to autism. It is hard to say what proportion of cases that are labeled as autism are really a matter of toxins in the body, and how many are a deficiency in vitamin D, and how many are something else.
Re proving efficacy, if they really were effective it would be extremely easy to prove so once and for all. A double-blind placebo-controlled study, with appropriate monitoring to ensure that there was no fraud.
It sticks out like a sore thumb that they never published this sort of study, which is considered by the whole scientific community as THE sort of study to do. There is no good reason why they can't. (Unlike something like comparing homebirth to hospital birth. That couldn't be done double-blind, or even single-blind, because it would be impossible for both the patient and doctor not to be aware of their location.)
Instead, the sorts of studies they do are comparing one vaccine to another. Or, vaccinating a population, exposing them to the disease, and seeing how many people catch it. If 90% of people don't catch it, they consider it 90% effective. But we don't know what percentage of people would have caught it if unvaccinated.
Because they haven't done the correct sort of studies, the only info we have to go on is government statistics about the rates of diseases in different years. If you look at that stuff, you see that all the "vaccine-preventable diseases" were steadily declining over decades, and the vaccines arrived last minute to take the credit. The theory that makes more sense to me is that improvements in sanitation were the cause.
Another fact that supports the sanitation theory is that in first-world countries the diseases disappeared at roughly the same rate, even if there was no vaccination for it. While in third-world countries, the diseases lingered long after the vaccinations were made widely available.
