The measles outbreak has grown to at least 166 cases in 18 states and the District of Columbia. Despite overwhelming evidence that the vaccine is safe, some parents are still not convinced.

To understand the anti-vaccine movement meet Nicholas Wildman, 19 years old, six feet tall, and still in diapers with severe autism.

His parents showed a video of him to CBS News' Ed Bradley on "60 Minutes" 15 years ago.

"I should have never have had him have that vaccine" for measles, mumps and rubella, his mother said.

Compelling video perhaps. But one problem: science has discredited the link, first floated by a British doctor named Andrew Wakefield in the journal The Lancet in 1998.

A nurse vaccinates a baby against diseases like measles. The current outbreak of the illness is said to be the result of some parents believing vaccinations are a cause of autism. CBS News

Dr. Paul Offit, director of the Vaccine Education Center at the Children's Hospital of Philadelphia denies a connection with vaccination and autism.

"Absolutely no doubt," he said. "MMR vaccine does not cause autism. It never made biological sense that it would and now we have all the epidemiological studies showing that it clearly didn't."

Offit says since Wakefield's article, there have been 14 studies looking at hundreds of thousands of children on three continents that show no linkage.

But why did Dr. Wakefield's hypothesis get any traction at all?

"Because we don't know what the cause or causes of autism was," said Offit. "Now he's got a reason, right? He's got a boogeyman."

Only in the view of science now, his boogeyman has been widely discredited. "It was just wrong."

The Lancet retracted the paper in 2010. The British Medical Journal called it "an elaborate fraud" and Dr. Wakefield lost his license. But still the fallout lingers, as we are seeing 17 years later with the current measles outbreak.

Offit says the current outbreak can be directly related to Dr. Wakefield's theory.

"No doubt about it," he said. "I think if you ask parents why is it you're hesitating to get this measles, mumps, rubella vaccine, I think many would say, 'I still think it's possible that this vaccine might cause autism.' "

But Offit, an early critic of Andrew Wakefield said there's no satisfaction in being right. He said this was not an "I told you so" moment, that whenever children suffer there is nothing good about it.