Donald Trump met Tuesday with Robert F. Kennedy Jr., an environmental activist and known skeptic of childhood vaccinations. Kennedy has been a prominent voice in the anti-vaccine community, raising questions for years about a possible (disproven) link between a preservative in some vaccines and autism.

Kennedy spoke to reporters after the meeting, which he said came at Trump's request, and noted that he would be heading up a commission on vaccine safety and "scientific integrity." The Trump transition team, however, later said a commission is not quite baked, noting in a statement that Trump is at this point "exploring the possibility of forming a commission on autism."

But the fact that Kennedy — who has lent his name and prominence to a controversial cause of whether vaccines, specifically the preservative called thimerosal, cause autism, for which there is no evidence within the scientific community — is part of that conversation, once again, reflects Trump embracing the fringe when it comes to the science of autism and vaccinations.

During the presidential campaign, Trump argued that he knew a child of an employee who had gotten a vaccine and then ended up with autism. That's despite the confluence of evidence to the contrary — from the Centers for Disease Control and Prevention and the overwhelming scientific body of research.

"President-elect Trump has some doubts about the current vaccine policies," Kennedy said, according to a pool report after the meeting at Trump Tower in New York, "and he has questions about it. His opinion doesn't matter but the science does matter, and we ought to be reading the science, and we ought to be debating the science. And that everybody ought to be able to be assured that the vaccines that we have — he's very pro-vaccine, as am I — but they're as safe as they possibly can be."

The Trump transition team later released this statement:

"The President-elect enjoyed his discussion with Robert Kennedy Jr. on a range of issues and appreciates his thoughts and ideas. The President-elect is exploring the possibility of forming a commission on Autism, which affects so many families; however no decisions have been made at this time. The President-elect looks forward to continuing the discussion about all aspects of Autism with many groups and individuals."

Alarm from medical authorities

Kennedy's announcement immediately provoked alarm among leading medical authorities. The American Academy of Pediatrics put out a statement reiterating that "vaccines protect children's health and save lives. They prevent life-threatening diseases, including forms of cancer. Vaccines have been part of the fabric of our society for decades and are the most significant medical innovation of our time. Vaccines are safe. Vaccines are effective. Vaccines save lives."

It's a topic that has been hotly debated for two decades and has incited strong passions among some parents of children with autism. Out of these fears, some parents have decided to forgo vaccinating their children.

As a result, some parts of the country saw a measles outbreak in 2015. There were "more cases of measles in the first month of 2015 than the number that is typically diagnosed in a full year," the New York Times noted. Of 34 California patients, 22 were of age to be vaccinated and never were; six were babies too young to be vaccinated, NPR reported. It spread to more than a dozen states.

Pushing conspiracies from the bully pulpit?

Trump, who has peddled numerous conspiracies, picked up the anti-vaccine charge in a high-profile way in a September 2015 debate.

"You take this little beautiful baby, and you pump — I mean, it looks just like it's meant for a horse, not for a child," Trump said, "and we've had so many instances, people that work for me. Just the other day, 2 years old, 2 1/2-years old, a child, 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."

But that link Trump tries to draw is simple, convenient and false.

Here was Ben Carson, a retired pediatric neurosurgeon, in that same debate: "We have extremely well-documented proof that there's no autism associated with vaccinations."

As NPR's Scott Horsley fact-checked after that debate: "Trump said all he's really advocating is that vaccines be spaced out over a longer period of time, though the American Academy of Pediatrics says there's no evidence that's necessary."

The academy noted in its statement Tuesday, "Claims that vaccines are linked to autism, or are unsafe when administered according to the recommended schedule, have been disproven by a robust body of medical literature. Delaying vaccines only leaves a child at risk of disease."

Discredited

The vaccine-to-autism link theory first came to prominence in 1997 with a now-discredited study in a British journal, The Lancet, which was withdrawn in 2010. It was authored by a surgeon, Dr. Andrew Wakefield, who has since lost his license to practice medicine. (More on that here.) That very researcher met with Trump last summer.

The Centers for Disease Control and Prevention has categorically stated, "There is no link between vaccines and autism." As far as thimerosal specifically, the CDC wrote:

"Research shows that thimerosal does not cause ASD [autism spectrum disorder]. In fact, a 2004 scientific review by the IOM concluded that 'the evidence favors rejection of a causal relationship between thimerosal-containing vaccines and autism.' Since 2003, there have been nine CDC-funded or conducted studies that have found no link between thimerosal-containing vaccines and ASD, as well as no link between the measles, mumps, and rubella (MMR) vaccine and ASD in children."

Most childhood vaccines have had just trace amounts of thimerosal in them for more than 15 years. The only ones that still have more in them are some flu vaccines. The CDC notes that the removal of thimerosal was done as a precaution and points out that there are flu vaccines without it also available.

What's more, some research suggests that autism develops in the womb. NPR noted in 2014:

"The symptoms of autism may not be obvious until a child is a toddler, but the disorder itself appears to begin well before birth. Brain tissue taken from children who died and also happened to have autism revealed patches of disorganization in the cortex, a thin sheet of cells that's critical for learning and memory, researchers report in the New England Journal of Medicine. Tissue samples from children without autism didn't have those characteristic patches."

A flawed messenger

Kennedy himself has come under fire for his facts and assertions on the potential link. Salon pulled completely from its website a story written by Kennedy in 2005 because of a series of factual errors. Salon noted that it published that piece "that offered an explosive premise: that the mercury-based thimerosal compound present in vaccines until 2001 was dangerous, and that he was 'convinced that the link between thimerosal and the epidemic of childhood neurological disorders is real.' "

But the story, co-published with Rolling Stone, had to be pulled after "we amended the story with five corrections (which can still be found logged here) that went far in undermining Kennedy's exposé. At the time, we felt that correcting the piece — and keeping it on the site, in the spirit of transparency — was the best way to operate. But subsequent critics, including most recently, Seth Mnookin in his book 'The Panic Virus,' further eroded any faith we had in the story's value. We've grown to believe the best reader service is to delete the piece entirely."

Part of a broader pattern

Trump happened to take the meeting with Kennedy on one of the busiest days in politics, in one of the busiest weeks in politics, since the presidential election. Trump's attorney general nominee, Jeff Sessions, is sitting for the first of two days of hearings questioning past allegations of racism and highlighting where he differs from the president-elect.

Meantime, there is another hearing happening related to Russian hacking and interference into the U.S. election at which the director of national intelligence and the director of the FBI — whom Hillary Clinton blames, in part, for costing her the election — are testifying on Capitol Hill. They said definitively that Russia was behind the interference and had the intent of undermining American democracy and trying to get Trump elected.

More than half a dozen other hearings are taking place in the coming days, including for Trump's nominee to be secretary of state — a hearing that is sure to be a proxy fight with Trump on the U.S. relationship with Russia.

It all follows a pattern of Trump in (1) utilizing something of a chaos theory of politics in throwing as much news as possible in all directions meant to distract and make the salience of news diffuse, and (2) once again believing what conforms to a predisposed view. Consider the way he has handled Russian interference into the 2016 election: He and his team have cast doubt on U.S. intelligence findings that Russia hacked the Democratic National Committee and a Clinton campaign official with the intent to undermine American democracy and get Trump elected.

Instead of treating that as a serious national security issue that demands a response, as most Republican elected officials have, he has focused on how there's no evidence any hacking affected the outcome of the election.

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