Is there any link between the MMR vaccine and autism?

Mumps, measles and rubella can lead to potentially deadly complications like pneumonia and encephalitis. 

But scientific research shows that MMR does not cause autism. For example, a study of more than half a million children in Denmark showed that the likelihood of autism was the same in kids who weren't immunized as those who were.

So why do some people think there's a link? Partly it's because children with autism are often diagnosed around the same time as they get their shots. Some people assume those events are related — but just because things happen close together doesn't mean they're connected.

It's just like: If you eat a ham sandwich and then get hit by a car. The ham sandwich did not cause the car to hit you.

Another reason is a now-discredited 1998 study that claimed to show a link between MMR and autism. It was led by a doctor who was also receiving consulting fees from lawyers planning to sue vaccine makers. Most of the study's authors have now disavowed its findings. And after a comprehensive review, the British Medical Journal concluded the study was "an elaborate fraud", involving falsified data and misrepresentations to the families involved.

The tragedy is that the myth of a connection with autism has caused real, devastating damage. In 2000, the autism scare caused MMR immunization rates in Ireland to drop to 76 per cent. Measles cases immediately soared to 1,200 infections, compared to 148 the year before — and several children died as a result.