In 2025, United States recorded the most measles cases in more than 30 years, Centers for Disease Control and Prevention data shows. A large share of the infections were connected to an outbreak in West Texas that led to the deaths of two children.

The total number of cases nationwide topped 2.000 by the end of the year, with infections confirmed in at least 44 states.

Measles is one of the most contagious infectious diseases, and in some cases, can cause severe infections in the lungs and brain that can lead to cognitive issues, deafness or death. But doctors and health officials say the vaccine, which is normally given as part of the combination measles-mumps-rubella (MMR) vaccine, is highly safe and effective.

While most people's symptoms improve, about 1 in 5 unvaccinated people who get measles will be hospitalized. About 1 out of every 1,000 children with measles will develop brain swelling that can lead to brain damage, and up to 3 of every 1,000 children who become infected will die, the CDC says.

The largest outbreak so far this year has been in West Texas, with over 760 confirmed infections before the state declared the outbreak officially over in August. A growing number of cases have also been reported in other states around the country. In South Carolina, for example, dozens of students were quarantined in October due to an outbreak.

The CBS News data team is tracking confirmed measles cases nationwide as new data is released by state health departments and the CDC. (The map below is updated on Wednesdays when the CDC releases its latest weekly numbers.)

The Texas outbreak primarily affected children and teenagers, nearly all of whom were unvaccinated or had an unknown vaccination status. State and local health officials confirmed the first patient who died was an unvaccinated school-aged child, and the second was an unvaccinated 8-year-old girl. Neither of the children had underlying health conditions, the Texas health department said. New Mexico also reported the death of an adult with measles.

The last measles death in the U.S. before this year was in 2019, when a 37-year-old man died from measles complicated by meningitis in California, according to CDC data.

Until now, the highest number of confirmed cases in the U.S. in recent years was 1,274 in 2019, driven by outbreaks in New York, California and Washington state, but most years the total has been much lower.

Health experts point to lower vaccination rates as a reason for increases in preventable diseases like the measles.

CDC data shows about 93% of kindergarteners in the U.S. were vaccinated against measles during the 2021-2022 school year and only 92.7% in the 2023-2024 school year. This is down from 95.2% during the 2019-2020 school year — a critical threshold to keep people safe.

"When more than 95% of people in a community are vaccinated, most people are protected through community immunity (herd immunity)," the CDC states.

Health and Human Services Secretary Robert F. Kennedy Jr., who has a history of making false and misleading claims about vaccines, voiced support for vaccination as the deadly outbreak spread in the Southwest.

"We encourage people to get the measles vaccine," Kennedy told CBS News chief medical correspondent Dr. Jon LaPook in an interview in April, marking the first time Kennedy has publicly urged people to get the measles vaccine since becoming HHS secretary.

Asked by LaPook what the federal government's official position on the vaccine is, Kennedy reiterated, "The federal government's position, my position, is that people should get the measles vaccine," but added, "The government should not be mandating those."

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