The US is in the midst of the worst measles outbreak in 33 years, according to figures released this week. Driven by an outbreak in Texas, the US has now seen more measles cases in 2025 than in any year since 1992.
Experts said they expect the growth in measles cases to continue, spurred on in part by the summer travel season. The best way to prevent measles is to be vaccinated against the disease.
“Given this is summer and more people are traveling all over the US and abroad, this will increase the spread of measles,” pediatric infectious disease expert at Northwestern University, Dr Tina Tan, said in a statement.
“People need to ensure that they, their children and their families are all up to date on their measles and other vaccines as this is the best way to protect and prevent persons from getting sick with measles and other vaccine-preventable diseases.”
The highly effective measles, mumps and rubella (MMR) vaccine has kept the disease at bay for decades. However, experts warn the US may be entering a “post-herd immunity” era after the Covid-19 pandemic, which disrupted routine childhood immunization visits, supercharged the reach of anti-vaccine groups and saw the rise of a wellness influencer culture.
“Measles really is an airplane ride away. It’s a car ride away. The reason we haven’t had it for 20 years is because of the high vaccination rates,” Katherine Wells, director of public health for the city of Lubbock, Texas, told Stat News. “And as soon as we start seeing that drop again, we have more vulnerable people, and that gives measles places to spread.”
Measles is one of the most contagious diseases known to medicine. It causes a characteristic top-down rash, runny nose, high fever and red, puffy eyes. Although most people recover from the disease, it hospitalizes as many as one in five and causes pneumonia in one in 20 children, according to the CDC. It can also cause serious complications, including brain swelling leading to permanent disability in one in 1,000 children and death in 1-3 in 1,000 children.
Health officials have reported 1,297 confirmed cases of measles in 2025, according to a dashboard from the Johns Hopkins University’s Center for Outbreak Response Innovation on Friday. The figures are slightly higher than those reported by federal health authorities at the Centers for Disease Control and Prevention (CDC), which reported 1,288 cases, but last updated their tally on Wednesday.
Both of those figures exceed the 1,274 cases reported in all of 2019. The next highest recent year was 1992, when 2,126 cases were reported. Importantly, that was before the US reached measles elimination status in 2000.
Three people have died in the 2025 outbreak, including two unvaccinated but otherwise healthy children in Texas, and one unvaccinated adult in New Mexico, according to state health authorities.
North Dakota is just one example of how difficult it has been for states to prevent measles cases. The state had just hit the 42-day milestone without any new cases – a federally set limit to declare the end to an outbreak – when an unvaccinated person traveled out of state and contracted the disease, according to the InForum, a local news outlet in North Dakota.
The health secretary, Robert F Kennedy Jr, one of the world’s best-known vaccine skeptics, has also disrupted US vaccine policy and spread inflammatory information about the MMR vaccine.
In June, Kennedy fired all 17 members of a vaccine advisory panel that is a key link in the distribution pipeline, and stacked the committee with seven ideological allies. The group declared in its first meeting that it would review the schedule of childhood vaccines and review older vaccines.
Kennedy’s changes to federal vaccine policy are now the subject of a lawsuit by a pregnant physician who was denied a Covid-19 vaccine. Kennedy unilaterally declared Covid-19 vaccines would no longer be recommended for healthy pregnant women, despite many studies showing they are at higher risk.