Carson dismissed the correlation between autism and vaccines at the debate, but affirmed the decision to have fewer of them so close together.
"It is true that we are probably giving way too many in too short a period of time," the retired neurosurgeon said at Wednesday's Republican presidential debate. "And a lot of pediatricians now recognize that and I think are cutting down on the numbers and the proximity in which those are done and I think that's appropriate."
Ford Vox, a brain injury specialist at the Shepherd Center in Atlanta, wrote in a CNN op-ed
that the schedule was developed for a reason.
"Each of the 12 vaccines administered to children target common causes of crippling and deadly childhood diseases and represent the fruition of many years of hard-won medical research and careful analysis by scientists and clinicians," he said.
And he criticized Rand Paul, an ophthalmologist, for suggesting that it is okay to spread out the vaccine schedule.
Rand Paul, an ophthalmologist, told the debate audience he doesn't trust the recommended schedule.
"[E]ven if the science doesn't say bunching them up is a problem, I ought to have the right to spread out my vaccines a little bit at the very least," said Paul, who's "all for vaccines. But I'm also for freedom," Paul said Wednesday.
Vox criticized both candidates for pandering to the wings of their party that are much more likely to reject vaccines.
"Neither neurosurgeons (Carson) nor ophthalmologists (Paul) are known to prescribe a lot of childhood vaccines, but as physicians both ought to have known better than to tacitly endorse Dr. Trump's medicine show," he said. "Instead both waffled and downplayed their responses, pandering to a GOP base enthralled with Trump, and in doing so lent credence to his bogus claim about autism and vaccines. Both docs seem to prefer prescribing "common sense" and folk wisdom to medical science and good public health policy."
CNN reached out to both the Carson and Paul campaigns for comment.
CNN Chief Medical Correspondent Dr. Sanjay Gupta agreed in a previous CNN op-ed
saying that the conversation about vaccines is about much more than science and medicine.
"Facts should matter, and science should win, but after 13 years as a medical reporter, I know it is not that simple," he said. "Science often loses the zeal argument to ideology, and in some ways it is easy to understand why. At the heart of the vaccine argument is the awesome challenge of trying to prove a negative."
The American Academy of Pediatrics also disagrees with both Carson and Paul. The vaccine schedule is one size fits all for a reason and it should not be spread out over a two to three year period, according to the group's website
"First, you would not want your child to go unprotected that long. Babies are hospitalized and die more often from some diseases, so it is important to vaccinate them as soon as it is safe. Second, the recommended schedule is designed to work best with a child's immune system at certain ages and at specific times," the group states on their website. "There is no research to show that a child would be equally protected against diseases with a very different schedule. Also, there is no scientific reason why spreading out the shots would be safer. But we do know that any length of time without immunizations is a time without protection."
And following spread out schedules have not been proven to be effective, according to the academy.
"There is no scientific basis for such a schedule. No one knows how well it would work to protect your child from diseases," the website said. "And if many parents in any community decided to follow such a schedule, diseases will be able to spread much more quickly. Also, people who are too sick or too young to receive vaccines are placed at risk when they are around unvaccinated children."