After more than 20 years without sustained transmission, the U.S. is dangerously close to losing its “measles-free” status if it does not stop an ongoing outbreak by January.

Experts warn that vaccination coverage in the U.S. has fallen below the 95% threshold needed to prevent outbreaks, with a growing number of communities reporting outbreaks in Utah, Arizona and South Carolina.

On Monday, the Pan American Health Organization, which serves as the World Health Organization’s regional office for the Americas, revoked Canada’s measles-free status.

It is likely that both the U.S. and Mexico will lose their measles-free designation in 2026, because both countries have had sustained outbreaks of measles since early 2025.

In total, more than 1,600 Americans in more than 40 states have gotten sick from measles in 2025. That is more cases than any year since 1992. More than 90% of the people who got sick were unvaccinated.