President Donald Trump on Monday signed an executive order backing fewer routine childhood vaccines, calling for the number of recommended shots to be reduced to 11 and for some vaccines to be administered separately. The order builds on the Trump administration’s efforts to reshape the childhood vaccine schedule under Health and Human Services Secretary Robert F. Kennedy Jr., a longtime vaccine skeptic.

Trump said the updated recommendations would bring the United States in line with other developed nations and described the changes as a matter of “common sense and knowledge.”

The executive order calls for separating the measles, mumps, and rubella (MMR) vaccine into three individual shots administered during separate visits.

Trump has repeatedly promoted spacing childhood vaccinations into separate medical visits. He also said Monday that one-year-olds should have their shots spread across five separate visits, though it was unclear whether he meant all vaccines given at that age or specific ones.

Public health experts have warned that splitting vaccines and requiring additional visits could increase the likelihood of missed appointments and skipped immunizations. They also said spacing out vaccinations could leave children vulnerable to vaccine-preventable diseases before they return for another visit.

Separate measles, mumps, and rubella vaccines for children are not currently available in the United States.

The order also directs the Department of Justice to investigate whether states are violating exemptions for childhood vaccine mandates, including parental authority, disability accommodations, religious exemptions, and medical reasons.

Under the draft recommendations, all children would receive vaccines against:

RSV monoclonal antibodies and vaccines against hepatitis A, hepatitis B, meningococcal B, meningococcal ACWY and dengue would instead be recommended only for high-risk populations. Some vaccines, including hepatitis immunizations, would involve shared decision-making between parents and doctors.

The order comes after HHS moved earlier this year to reduce the number of vaccines recommended for children, a change that was challenged in court by medical groups.

Trump also falsely linked childhood vaccines to autism, suggesting that increased vaccination rates had contributed to rising autism diagnoses. Decades of scientific research have found no evidence of a connection between childhood vaccines and autism.

The order comes as the US faces a measles outbreak that experts have warned could threaten the country’s measles elimination status.