President Donald Trump signed an executive order on Aug. 10, 2026, calling for the combined measles, mumps and rubella vaccine to be given as three separate shots at three separate appointments. The combined MMR vaccine is currently given at 12 to 15 months of age and again between ages 4 and 6.

In the order, Trump also urges states to revisit their school vaccination laws and instructs the Justice Department to challenge state rules on religious and medical exemptions.

It is the latest move in the administration’s effort to dismantle the U.S. childhood immunization schedule, a set of recommended vaccines given from birth through adolescence to prevent a range of serious infections that has been in place in some form since 1995. The order endorses the January 2026 decision by the Department of Health and Human Services that cut universally recommended childhood vaccines from 17 diseases to 11 – despite the fact that those changes were blocked by a federal court in March 2026.

An executive order cannot by itself change which vaccines are recommended or required, but it sets the administration’s direction and puts federal agencies to work on it.

I am an infectious disease physician who treats vaccine-preventable diseases and reviews the clinical trial evidence behind immunization recommendations. The most important thing for parents to know is that this order changes nothing at the pediatrician’s office. Every vaccine on the schedule remains available and covered by insurance, the American Academy of Pediatrics continues to recommend the full set, and no new evidence prompted any of this.

What the order will do is create confusion at a bad moment. It arrives as children return to school, when measles cases are at their highest number since 1991, and it tells parents that a vaccine their pediatrician recommends should be broken into three shots that no longer exist in this country. In the longer term, the order’s most consequential provisions are aimed at state school vaccination requirements, which is where American vaccine policy is actually made.

A science-backed schedule

The U.S. childhood immunization schedule, the grid of colored bars that pediatricians share with parents and which explains when and what vaccines all children should receive, wasn’t designed in a single stroke. It was built gradually over decades, shaped by disease outbreaks, technological........

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