Despite claiming he is not anti-vaccination, De Niro has insisted his son changed “overnight” when he received the MMR jab, which immunises against Measles, Mumps and Rubella.
The 72-year-old, whose son is now 18, was meant to screen Vaxxed: From Cover-up to Catastrophe at the Tribeca Film Festival, but scrapped his decision to do so for fear of a backlash.
But despite bowing to his worries, Robert has urged people to see the movie so they can "make up their own judgement" about the issue.
“Let’s find out the truth,” De Niro urged, who also described himself as “pro-safe vaccine.”
The veteran actor, whose 18-year-old son Elliott suffers with autism, said he hoped screening the film would start a conversation about the link between the vaccine and the disorder.
He told The Today Show: “There's a lot of things that are not said. Nobody seems to want to address that, or they say they've addressed it and it's a closed issue.
“But it doesn't seem to be because there are many people who say they saw their kid change overnight.
“My wife says that (is what happened to my son). I don't remember. But my child is autistic.
“I, as a parent of a child who has autism, I'm concerned, I want to know the truth.”
Many filmmakers threatened to pull out of Tribeca film festival due to the documentary, which was why the actor decided to pull it.
The film was directed by Andrew Wakefield, who started the MMR controversy back in the 90s when he published an article in British medical journal The Lancet.
In it, he linked a bowel disease, autism and the MMR jab, kickstarting a suspicion of vaccinations that led to a drop in immunization rates both in the UK and US.
This in turn triggered an outbreak of Measles in Europe and the US – the scale of which had not been seen in decades.
However, in 2010, The Lancet journal retracted the paper as the result of an investigation by a British newspaper. Wakefiled’s study was widely discredited and he was permanently stripped of his medical licence.