The US just lost its measles elimination status after more than 20 years, mainly because of a big outbreak in Utah with more than 700 cases.
Health officials say there is now ongoing spread of the virus, which is a big step back from when measles was declared eliminated in the US in 2000.
US vaccinations decline, 9 measles deaths
Fewer people are getting vaccinated, and trust in federal health advice has dropped since the pandemic.
The CDC is also dealing with staff cuts and debates over changes to the MMR vaccine policy.
With nine deaths from measles this year (triple last year's count), health experts are stressing how urgent it is to stop the spread and get vaccination rates back up.