The Institute of Medicine did a report saying there's no correlation between infant immunizations causing autism. If there was you would see a decrease in the incidence of autistic spectrum disorders because thimerosal, the mercury containing preservative, isn't used in unit doses, i.e. the way kids get their shots now for a few years already. IIRC, thimerosal is only used in multi dose annual influenza vaccines.
What has happened is that the definition of autism has been broadened as to be almost unrecognizable. This makes the number not credible, IMO.
The decrease has been established. Shhhh, they don't want the public to know.
Autism Rates Drop After Mercury Removed From Childhood Vaccines
03 Mar 2006
An article in the March 10, 2006 issue of the Journal of American Physicians and Surgeons shows that since mercury was removed from childhood vaccines, the alarming increase in reported rates of autism and other neurological disorders (NDs) in children not only stopped, but actually dropped sharply - by as much as 35%.