I'm going to hop on my anti-anti-vaxxer soapbox for a moment.
There is currently a measles outbreak in Ottawa. Without question, the outbreak is the result of people deciding not to have their children immunized with the MMR vaccine. (Measles, Mumps and Rubella, for those who didn't waste a large number of their formative years watching ER and House.)
In 1998, Andrew Wakefield (I refuse to give him the title doctor), published a study linking the MMR vaccine to autism. It has since been proven to be a total fraud with hand-picked cases, altered medical records and falsified lab data. However, a substantial fraction of parents decided not to immunize their children based on it. This dropped the level of immunization down below the level of herd immunity and people (especially small children) began to be blinded, deafened and killed from measles for the first time in half a century.
Measles is a particularly difficult disease to avoid since the patient is contagious for 3 weeks before displaying any symptoms. It's very easy to catch if you haven't been immunized, usually only with a single exposure. People with weakened immune systems, children under 2 and pregnant women are likely to have severe complications.
An doctor wrote an article in the Globe and Mail talking about how mothers will walk miles across minefields in developing countries in order to get their children vaccinated. It makes her sad to know that somewhere this year, doctors will have to tell mothers in the Western world that their children died because of an entirely preventable disease. And likely not because they chose not to vaccinate, but because people around them chose not to.
I recognize that autism can be scary and it's human nature to reach for an easy explanation. When we have countless examples of companies hiding results to avoid profit loss or "studies" which are really just advertisements for the sponsoring companies, it's hard to know who to trust.
I highly recommend the book The Panic Virus by Seth Mnookin to look at the autism-vaccine question in detail.