President Donald Trump said Friday that his administration plans to recommend splitting certain routine childhood immunizations into five separate shots. Trump described them as “20% doses” that would be administered at six month intervals, an approach vaccine experts warned would leave children without effective protection.

“Instead of a child going in and having a tremendous amount of different vaccines pumped into a big proportion of the body … we’re going to recommend that they do five doses marked one, two, three, four, five and that they be given in six-month intervals, so that a small amount of the vaccine gets pumped into the body,” Trump said.

Dr. Paul Offit, director of the Vaccine Education Center at the Children’s Hospital of Philadelphia, said such a plan would render vaccines ineffective without making them safer. Offit, who is also a vaccine inventor, called the idea “buffoonery.”

Trump did not make clear which immunizations would be affected by the proposed recommendation. He specifically mentioned only the polio vaccine, which he said has “been amazing.”

The president also said that “certain vaccines were taken out because they’re not needed until the child would be much older.” The comment appeared to refer to the federal childhood vaccine schedule, which the administration attempted to overhaul this year before a federal judge temporarily blocked it.

Trump suggested that the schedule changes he discussed could produce a “massive reduction in autism.” However, extensive scientific studies of vaccines have found no evidence connecting vaccination to autism.

The US Department of Health and Human Services did not respond to CNN’s request for additional information about the plans. HHS Secretary Robert F. Kennedy Jr. stood beside Trump while the president outlined the proposed vaccine changes.

Kennedy had received a standing ovation Thursday at a conference held by Children’s Health Defense, a vaccine opposition advocacy group that he previously led. Delivering the keynote address, he praised Trump’s support for vaccine skeptics and told attendees, “you have a strong and steadfast friend at the White House.”

Kennedy also told the gathering that he would “stay in this fight.” His appearance came as the administration continued pursuing major changes to federal childhood vaccination policy.

In August, Trump signed an executive order intended to reshape the federal government’s approach to childhood vaccines. He argued that infants should receive fewer immunizations over a longer period and advised separating the measles, mumps and rubella vaccine, commonly called MMR, into three individual shots despite little scientific evidence supporting the change.

Trump previously claimed that “large amounts – like vats of vaccine – are currently pumped into your child’s body.” He also compared the supposed fluid volume to “the size of a bottle of soda” and portrayed that amount as dangerous.

The standard MMR vaccine dose administered to children at about 12 months of age is 0.5 milliliters, also called CCs. That quantity is approximately one tenth of a teaspoon.

Offit said vaccine doses and schedules are extensively studied to optimize both safety and effectiveness. Reducing each administered dose while increasing the number of appointments would prevent the vaccines from working, he said, while providing no safety benefit.

“When you create a vaccine, you do a dose response curve, and you’re trying to give the least amount of vaccine that induces an immune response that’s protective. So you don’t want to give too much, where you know you don’t need all that, and you don’t want to give too little, where it’s you know sub-immunogenic,” Offit said.

Offit explained that a sub immunogenic dose would fail to induce the needed immune response. “What he’s suggesting would not work. He’s basically saying he wants to give vaccines in a manner in which they wouldn’t be protective.”

He also rejected claims that standard vaccination overwhelms babies’ immune systems, arguing that vaccines expose people to far less than they naturally encounter. “Vaccines are literally a drop in the ocean of what you encounter and manage every day.”

“The notion that vaccines in any way are overwhelming your immune system, causing chronic disease, is just fanciful,” Offit said. He noted that the body makes a billion new B and T cells each day to handle viruses and bacteria in the surrounding environment.