ON SCREEN: Measles cases are at a record high since the disease was declared wiped out in 2000. Last month President Trump urged parents to vaccinate children.

ARCHIVAL (MSNBC, 4-26-19):PRESIDENT DONALD TRUMP: They have to get the shots. The vaccinations are so important.

ON SCREEN: Thats a turnaround. In the past, he has raised doubts about vaccine safety concerns based on flawed research.

NARRATION: Over the last few years, Donald Trump has suggested there is a connection between the MMR vaccine and autismeven though there is no scientific evidence of a connection after numerous studies.

SETH MNOOKIN: There is data from millions and millions of children around the world and it all comes back showing the same thing that there is zero association. It doesnt matter how many vaccines you get, it doesnt matter when you get them. There is just no correlation whatsoever.

ARCHIVAL (REPUBLICAN DEBATE, 9-16-15):DONALD TRUMP: Weve had so many instancespeople that work for me. Just the other day, two years old, two and a half years old, a beautiful child, went to have the vaccine and came back and a week later got a tremendous fever, got very, very sick. Now is autistic. I only say, Im in favor of vaccines, do them over a longer period of timesame amount, just in little sections

NARRATION: At a fundraiser during the campaign, Trump met with several anti-vaxxers, including the discredited researcher, Andrew Wakefield.

Why is this a big deal?

SETH MNOOKIN: The current vaccine scares and controversies that were still dealing with today stem from a 1998 paper by Andrew Wakefield that appeared in The Lancet, a very respected medical journal published out of the U.K.

ARCHIVAL (ITN, 1998):NEWS CLIP: Its a dilemma.

NARRATION: Despite the fact that it was a preliminary study, the British media ran with it.

ARCHIVAL (ITN, 1998):NEWS CLIP: Doctors at the Royal Free Hospital believe they may have discovered a link between the combination vaccine and a bowel disease that can progress to autism.

ARCHIVAL (ITN, 1998):ANDREW WAKEFIELD: We would not come to this nor present this study for publication at The Lancet unless we had conducted extensive biological studies already.

NARRATION: But, actually there were some major problems with Wakefields study first of all, it was comprised of only 12 children.

SETH MNOOKIN: The notion that you would take a 12-person case study and make claims about a population as a whole is ridiculous.

NARRATION: And thats not all. There was a major conflict of interest at play.

SETH MNOOKIN: Right before this paper came out, Andrew Wakefield took out a patent for an alternative measles vaccine, of exactly the type that parents would want if his hypothesis was true.

NARRATION: And then there was Wakefields financial interest in making the connection between the MMR vaccine and autism.

SETH MNOOKIN: Andrew Wakefield was receiving money from a lawyer who was working with parents intent on suing vaccine manufacturers.

NARRATION: Wakefield was paid approximately $674,000 for his work on the case.

SETH MNOOKIN: Another thing, he claimed, in the paper, that the children that he looked at were just a random group of kids. It turns out that many of them were actually sent to him by this lawyer.

NARRATION: And when Wakefield needed a control group of healthy children he took blood samples from kids attending his sons birthday party.

SETH MNOOKIN: When I first heard about it my immediate thought was, worst birthday party ever. And, perhaps the most shocking revelation is that he faked some of the data.

NARRATION: An investigation by the British Medical Journal, BMJ, found that Wakefield had altered or misrepresented all 12 of the cases he had cited.

And 10 of his original co-authors withdrew their names from the study.

SETH MNOOKIN: Andrew Wakefield lost his license a couple of years ago, close to the period in time when The Lancet paper was retracted.

NARRATION: Despite losing his medical license and follow up studies on hundreds of thousands of children that contradict his findings, Wakefield feels optimistic since Trumps election.

He recently told STAT News that he found Trump genuinely interested, and open-minded on this issue.

ON SCREEN: Andrew Wakefield maintains that his research was valid. At an anti-vaccine rally in May 2018 he said: I wanted to reassure you that I have never been involved in scientific fraud.