Health organizations were quick to respond and try to correct the record, after statements made Wednesday night during the second Republican primary debate regarding vaccines and autism.
The topic came up when CNN moderator Jake Tapper asked Dr. Ben Carson, a retired neurosurgeon, about his thoughts on Donald Trump's repeated assertions that childhood vaccines are linked to autism -- a claim that has been widely discredited by the medical community.
At first, Carson responded by saying: "There have been numerous studies, and they have not demonstrated that there is any correlation between vaccinations and autism."
But his defense of vaccines grew a bit hazier as he went on: "Vaccines are very important. Certain ones. The ones that would prevent death or crippling. There are others, there are a multitude of vaccines which probably don't fit in that category, and there should be some discretion in those cases."
Trump rebutted by saying "autism has become an epidemic" that has "gotten totally out of control" and suggested that vaccines, or at least high concentrations of them at once, directly cause autism.
He told a story of someone he said he knew: "Just the other day, two years old, 2½ 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," he said.
The belief that vaccines cause autism -- held by a small but vocal group of people making up the so-called anti-vax movement -- was heavily fueled by a 1998 study that was later retracted after it was found to be based on fraudulent data.
Decades of research from the Centers for Disease Control and Prevention and medical organizations around the world have found no evidence of a link between vaccines and autism.
The statements from the GOP debate drew quick criticism from doctors and autism advocacy groups.
"Donald Trump is a part of a fringe movement that includes Jenny McCarthy and others who have dangerously perpetuated the false link between vaccines and autism," Alison Singer, president and co-founder of the Autism Science Foundation, said in a statement. "The facts are clear. Vaccines do not cause autism. Some people may not like the facts, but they don't get to change them, even if they are running for president of the United States."
Singer pointed to the measles outbreak that spread at Disneyland earlier this year as an example of what happens when children aren't vaccinated. "We have seen the effects of misinformation on our children's health," she said.
During the debate, Trump asserted that he is "totally in favor of vaccines" but said he wants "smaller doses over a longer period of time."
Carson seemed to agree with this. "It is true that we are probably giving way too many in too short a period of time," he said. "And a lot of pediatricians now recognize that, and, I think, are cutting down on the number and the proximity in which those are done, and I think that's appropriate."
Sen. Rand Paul, who is also an ophthalmologist, echoed that concern, saying: "I'm all for vaccines, but I'm also for freedom. I'm also concerned with how they're bunched up."
But this notion was quickly shot down by pediatricians and health organizations.
"There is no 'alternative' immunization schedule. Delaying vaccines only leaves a child at risk of disease for a longer period of time; it does not make vaccinating safer," Dr. Karen Remley, Executive Director of the American Academy of Pediatrics, said in a statement.
In a press conference held today by the CDC about the flu, Dr. Wendy Sue Swanson, a pediatrician and executive director of digital health at Seattle Children's Hospital, agreed there is no evidence that delaying vaccines is safer or more effective than the standard schedule set by the CDC. She echoed Remley's statement that skipping or delaying vaccines leaves children vulnerable to life-threatening diseases.
"Vaccines work, plain and simple," Remley said. "Vaccines are one of the safest, most effective and most important medical innovations of our time. Pediatricians partner with parents to provide what is best for their child, and what is best is for children to be fully vaccinated."