In 2017, Trump seemed to have forgotten his position, but the myth was apparently still on his mind.
Josh Keefe at Newsweek:
In newly released footage from a Bill and Melinda Gates Foundation event, Microsoft co-founder Bill Gates said President Donald Trump told him he was considering a commission to look into the “bad effects” of vaccines. "Don't do that," Gates said he told the president, and Trump has never publicly proposed such a commission. Yet the incident recalls Trump's longtime skeptical comments about vaccines.
Gates said that in two separate meetings since he was elected, Trump asked the billionaire philanthropist if “vaccines weren’t a bad thing.”
“He was considering a commission to look into the bad effects of vaccines and somebody, I think his name was Robert Kennedy Jr., was advising him that vaccines were causing bad things,” Gates recalled. “And I said ‘No, that's a dead end, that would be a bad thing, don’t do that.”