So if it was in 1998 it would have been based on the claims of Andrew Wakefield, right? He claimed a link between the MMR jab and austism. He said parents should not give their children the MMR jab because of this risk but instead give separate vaccines (that he could recommend).
Problem 1: he had a study group of 12 children. Too tiny to be meaningful in any way shape or form.
Problem 2: it was mostly anecdotal evidence.
Problem 3: It turned out he was being paid by lawyers who were preparing a lawsuit against the MMR vaccine manufactures.
Problem 4: He had personally filed a patent for a rival vaccine.
Problem 5: No other scientist could replicate his findings. At all.
It was a monumental fraud.
Maybe when this came to light it was when your documentary was pulled as it was full of lies, holes, and conflict of interest and could therefore not go out to the public. I am sure the documentary makers had good intentions, just as Private Eye magazine did as they picked it up and I have the utmost respect for that publication. It eventually turned on Wakefield as did the medical establishment once his fraud came to light.
It should also be noted that when his claims came to light people were genuinely concerned - who wouldn't be? As a result public confidence in the MMR vaccine plummeted as did usage, far below the 95% mark generally needed for herd immunity (some reports say as low as 80%). Weirdly enough this led to outbreaks of measles, hospitalisations and deaths from what was previously a very well controlled disease.
Finally, The Lancet fully retracted his paper. The General Medical Council found him guilty of serious professional misconduct and struck him off the medical register. He can no longer practice medicine in the UK.
Yes, I followed this case closely firstly in Private Eye, but it was all a fraud. Your documentary was pulled because it was false and the production company (and broadcaster) would have been sued to oblivion. Good intentions in the investigation, but no way could it be broadcast once the fraud came to light.
I hope that helps explain it for you.