Measles infections in the United States are on track to surpass their highest annual level in decades, with nearly 1,200 confirmed cases reported so far in 2025, including dozens among fully vaccinated individuals, according to data released Friday by the Centers for Disease Control and Prevention.
Of the 1,197 confirmed cases, at least 3%-approximately three dozen-were in individuals who had received both recommended doses of the measles, mumps, and rubella (MMR) vaccine. Another 2% of infections occurred in people who had received at least one dose, CDC officials said.
Texas, the epicenter of the country's most significant outbreak this year, recorded its 21st fully vaccinated case on Tuesday, state officials confirmed. "The first 20 cases did not result in hospitalizations," said Lara Anton, spokesperson for the Texas Department of State Health Services. Those patients were all children aged 8 or younger, and none had received post-exposure prophylaxis, she added.
In Colorado, six cases have been documented in fully vaccinated individuals, according to state health officials. "None of the six cases with 2+ doses were seniors or required hospitalization," said Hope Shuler, spokesperson for the Colorado Department of Public Health and Environment.
The CDC emphasized that while the MMR vaccine remains highly effective-providing 97% protection after two doses-waning immunity, international travel, and gaps in vaccination coverage are contributing to the ongoing spread. "Additional cases have been seeded from the outbreak in Texas, as well as related outbreaks in Mexico and Canada," said Brian Wakeman, deputy lead of the CDC's measles laboratory task force.
International outbreaks are also expanding. Ontario, Canada has recorded 2,083 cases since mid-October and reported its first measles-related death on June 5-a baby with congenital measles and preexisting conditions. Alberta has reported 868 cases, while the Mexican state of Chihuahua has logged 2,179 cases and four deaths as of Friday.
In the U.S., three deaths from measles have been confirmed in 2025: two elementary school-aged children in West Texas and an adult in New Mexico-all unvaccinated.
The CDC is urging summer camps to document measles immunity among campers and staff and recommends post-exposure vaccination within 72 hours for anyone not fully immunized. "If administered within 72 hours of initial measles exposure, MMR vaccine might provide some protection against infection or modify the clinical course of disease," the agency said.
Measles, declared eliminated from the U.S. in 2000, remains highly contagious. It spreads through the air and can linger in a room for up to two hours after an infected person has left. Symptoms include high fever, cough, red eyes, and a distinctive rash that typically begins on the face before spreading across the body.
Outbreaks have now been reported in 36 states, including Alaska, California, Florida, Illinois, Michigan, New York, Ohio, and Texas. Though several earlier outbreaks in states like Indiana, Michigan, and Pennsylvania have been declared over, the national tally remains on pace to exceed the 1,274 cases recorded in 2019-the highest annual total since 1992.
Health officials are particularly concerned about Americans vaccinated with a "killed" virus version of the measles vaccine before 1968. "That group is unlikely to have robust immunity from infection, because at that point in time, they were using less effective vaccines," said Dr. Celine Gounder, editor-at-large for public health at KFF Health News.
