If states don't tighten vaccine exemption laws, the federal government may step in, U.S. Food and Drug Administration Commissioner Scott Gottlieb said.
"Some states are engaging in such wide exemptions that they're creating the opportunity for outbreaks on a scale that is going to have national implications," the FDA head said in an interview with CNN.
Gottlieb's comments come as some states are considering proposals that would change vaccine exemptions for personal or philosophical reasons. He first made the comments in an interview with Axios.
Gottlieb told CNN that "certain states" could "force the hand of the federal health agencies" if they don't make changes.
However, the FDA has not made any plans or announcements, and it's not certain the agency will.
In Washington state, lawmakers are considering two bills amid a measles outbreak that has infected at least 64 people in the state. One would ban personal or philosophical exemptions for the measles, mumps and rubella vaccine. A second bill would ban personal or philosophical exemptions for all vaccines required by schools and licensed day cares.