It can all be blamed on Jenny McCarthy and Oprah Winfrey. McCarthy wrote a book about her belief that the specific vaccine that treats three childhood diseases gave her child Autism, and because Oprah generally has incredible (nigh on megalomaniacal) sway with large demographics of the world. McCarthy's book got a lot more traction than it probably ever should have.
Let's face it, it's a book written by Jenny McCarthy, a woman with no credentials in the field and I'm sure it's lacking in research as well.
EDIT: That being said, I knew a kid in high school who was on the Autism spectrum and he had been highly vaccinated as an infant, however, it should be noted he was not just getting the standard suite of childhood vaccinations, he was getting the whole suite of travel prophylactics, every time his family moved to a new country, which because of his father's job, was a lot all over the world.
It has some credence because he was an identical twin, but looked drastically different from his brother (he was short and squat and his brother was much taller and not nearly as squat). That being said again, he received well over what any child would ever receive, and vaccines that a child would probably never receive. You shoot anyone up with enough of anything and bad thing are going to happen.