US surpasses 4,000 measles cases with infections confirmed in 45 states: CDC
Most cases are among those unvaccinated or with unknown status, CDC data shows.
Measles cases in the United States have surpassed 4,000 this year, according to data updated Friday from the Centers for Disease Control and Prevention (CDC).
A total of 4,080 cases have been confirmed, with most reported by 45 states and Washington, D.C. Eighteen of this year's total have been among international visitors to the U.S., according to the CDC.
Five measles-associated deaths have been confirmed so far in 2026, all of them in Pennsylvania, according to health officials in the state.
The CDC has only recognized two deaths so far this year, with the agency saying that "number is subject to change."
The majority of measles cases in 2026 have been confirmed among children and teenagers aged 19 and younger, according to the CDC. About one in 10 children under age 5 have been hospitalized, CDC data shows.
About 95% of cases are among people who are unvaccinated or whose vaccination status is unknown, according to agency data.
Meanwhile, 2% of cases are among those who have received just one dose of the measles, mumps, rubella (MMR) vaccine and 2% of cases are among those who received the recommended two doses, according to the CDC.
"It's very telling," Dr. Peter Chin-Hong, an infectious diseases specialist and associate dean for regional campuses at the University of California, San Francisco, told ABC News of the breakdown in cases by vaccination status. "It's not a surprise, but it's chilling in many ways."
According to Chin-Hong, the official total of confirmed cases likely does not reflect the full picture of measles in the U.S. He said it's probable that there are many families with measles cases who never got tested.
"The story's not been fully told yet," he said. "In other words, the official numbers are only part of the picture and the reason why I think so is because the number of deaths and hospitalizations suggests that there are many more people who are infected but unaccounted."
The CDC currently recommends that people receive two doses of the MMR vaccine, the first at ages 12 to 15 months and the second between 4 and 6 years old. One dose is 93% effective, and two doses are 97% effective against measles, the CDC says.
However, CDC data shows vaccination rates have been lagging in recent years. During the 2025-26 school year, 92.4% of kindergartners received the MMR vaccine, according to data. This is lower than the 95.2% seen in the 2019-20 school year, prior to the COVID-19 pandemic.
"Unlike many of the healthcare issues or diseases that affect so much of the population ... we have the tool," John Brownstein, an epidemiologist and chief innovation officer at Boston Children's Hospital and an ABC News contributor, said. "It's a vaccine that is incredibly effective and the goal is to close vaccination gaps."
He noted that authorities have a responsibility to offer straightforward advice to the public.
"We need federal leadership that is really clear on the need for vaccination. We need local communities that are providing clear guidance and education and support to make decisions," Brownstein said. "I think we need to have a very aligned view on ... the impact of measles when communities are under-vaccinated."
Some public health specialists previously told ABC News they believe the U.S. is on track to lose the elimination status it earned in 2000.
The specialists said there are several reasons for the U.S. breaking measles case records for the second year in a row, including declining vaccination rates, people not fearing the measles virus, a loss of trust in public health institutions and a perceived lack of clear guidance and communication from the nation's top public health officials.
"I think there's a very strong chance that we would lose our elimination status because we're seeing the signs that measles is becoming continuously established here in the U.S." Brownstein said. "For a country with resources and an ability to provide protection, it's really unfortunate that we're seeing these tides turn on this very preventable disease."
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