Measles cases in US hit highest level since 1991, CDC data shows

The United States has recorded 2,318 confirmed measles cases, the highest annual total since 1991, according to the U.S. Centers for Disease Control and Prevention (CDC). The latest figures, released on Friday, surpass the 2,289 cases reported in all of 2025, highlighting a significant resurgence of the highly contagious disease.

Of the total, 2,302 cases were reported across 45 U.S. jurisdictions, while 16 cases were identified among international visitors to the country as of Thursday. The majority of infections have occurred in people who were unvaccinated or had unknown vaccination status, with children accounting for a substantial proportion of cases.

Health officials say the surge has been driven by multiple outbreaks linked to declining childhood vaccination rates in some communities. Measles spreads easily through the air when an infected person coughs or sneezes, and can lead to serious complications including pneumonia, brain swelling (encephalitis), hearing loss, and death, particularly among young children and people with weakened immune systems.

The CDC continues to urge people to ensure they are protected with the measles, mumps and rubella (MMR) vaccine, which is about 97% effective after two doses. Public health experts warn that maintaining high vaccination coverage is essential to preventing further outbreaks and protecting vulnerable populations.