US measles cases hit highest number in 33 years: CDC

Measles cases in the United States have reached their highest number in more than 30 years, according to new federal data published Wednesday.

There have been 1,288 confirmed measles cases across 38 states nationwide, according to the Centers for Disease Control and Prevention (CDC). By comparison, the U.S. recorded 285 cases all of last year, CDC data showed.

This marks the highest number of cases since 1992. The previous high occurred in 2019 when the U.S. reported 1,274 cases.

"I think this is unfortunately just the beginning," Dr. Peter Hotez, a professor of pediatrics and molecular virology at Baylor College of Medicine in Houston,, told ABC News. "I think things will continue to worsen in the United States in terms of return of childhood illnesses and ... I'm quite worried that what we're seeing in the U.S. is not going to stay in the U.S."

The states with confirmed cases include: Alaska, Arkansas, Arizona, California, Colorado, Florida, Georgia, Hawaii, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Missouri, Montana, Nebraska, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington and Wyoming.

Among the nationally confirmed cases, the CDC said 92% are among people who are unvaccinated or whose vaccination status is unknown.

Meanwhile, 4% of cases are among those who have received just one dose of the measles, mumps, rubella (MMR) vaccine and 4% of cases are among those who received the required two doses, according to the CDC.

A spokesperson from the Department of Health and Human Services (HHS) told ABC News in a statement on Wednesday that the agency "continues to support community efforts in dealing with the measles outbreaks. CDC continues to provide technical assistance, laboratory support, and vaccines as requested."

"The risk of measles infection is low for the overall U.S. population, with a case rate of less than 0.4 per 100,000 people -- lower than peer developed countries including Canada, the United Kingdom, France, Spain, and Italy," the statement continued. "Measles risk is higher in U.S. communities with low vaccination rates in areas with active measles outbreaks or with close social and/or geographic linkages to areas with active measles outbreaks."

According to the CDC, there have been at least 27 outbreaks this year, accounting for 88% of confirmed cases. By comparison, 16 outbreaks were recorded in 2024.

Texas experienced a large outbreak this year, with 753 cases reported since January. The rate of spread has slowed in recent weeks, with few cases reported.

At least two school-aged children have died. Both were unvaccinated and had no known underlying conditions, according to Texas health officials.

A third measles death was recorded in New Mexico among an unvaccinated adult who tested positive after dying, according to the New Mexico Department of Health.

The CDC currently recommends that people receive two MMR vaccine doses, the first at 12 to 15 months of age and the second between 4 and 6 years old. One dose is 93% effective, and two doses are 97% effective, the CDC says.

Measles was declared eliminated from the U.S. in 2000 due to a highly effective vaccination program, according to the CDC. However, CDC data shows vaccination rates have been lagging in recent years.

The rate of kindergarteners receiving state-required vaccinations dropped from 95% during the 2019-2020 school year to less than 93% during the 2023-2024 school year.

About 280,000 U.S. kindergarteners, or 7.3%, are not fully vaccinated with the two-dose measles vaccine.

Herd immunity – which is when enough people are immune to a disease that it can't spread from person to person -- is typically reached when more than 95% of people in a community are vaccinated.

Hotez said the national -- and state -- vaccination rates seem good at first glance, but the problem lies in county level vaccination rates, which can be quite low.

"What you're seeing is ... counties that are consistently way below 90% and and that's where you get into problems," he said "That's where ... you lose herd immunity."

The HHS spokesperson said the CDC "continues to recommend MMR vaccines as the best way to protect against measles," but also said the decision to receive the vaccine is "a personal one."

"People should consult with their healthcare provider to understand their options to get inoculated and should be informed about the potential risks and benefits associated with the vaccine," the spokesperson said.

Hotez is worried that if measles cases continue to spread, the U.S. is at risk of losing elimination status.

"If you can show that you're not seeing sustained measles transmission for more than 12 months, then then you've reached that point of saying measles is eliminated and that actually occurred in 2000," he said. "Now starting with this measles epidemic that began in Texas ...it looks to me like it could continue for that full 12 months. ... So I'm worried about losing our measles elimination status, which means stopping sustained transmission."