New Study Finds Measles Could Become Endemic if Childhood Vaccination Rates Don’t Improve

A new analysis published by epidemiologists at Stanford University found that with current state-level vaccination rates, measles could reestablish itself and become endemic in the United States during the next 20 years.  If current vaccination rates stay the same, the university’s model estimated that the U.S. could see more than 850,000 cases, 170,000 hospitalizations, and 2,500 deaths during the next 25 years. Under a 50% decline in childhood vaccination in the U.S., the simulation model predicted 51.2 million measles cases during the next two decades.  

The study found childhood vaccination at a high coverage level is needed to prevent resurgence of vaccine-preventable infectious diseases and their infection-related complications in the U.S. 

As of April 24, a total of 884 confirmed measles cases were reported by 29 states. Since last week, more than 80 new cases have been confirmed and four new states—Illinois, Louisiana, Missouri, and Montana—have reported measles cases. Other states that have reported measles cases this year include: Alaska, Arkansas, California, Colorado, Florida, Georgia, Hawaii, Indiana, Kansas, Kentucky, Maryland, Michigan, New Jersey, New Mexico, New York City, New York State, Ohio, Oklahoma, Pennsylvania, Rhode Island, Tennessee, Texas, Vermont, Virginia, and Washington.  

Tennessee health officials confirmed a measles outbreak on April 24, pushing the number of U.S. states with active outbreaks to 11. Ohio reported 32 confirmed cases on Thursday. Other states with active outbreaks are Texas, New Mexico, Indiana, Kansas, Michigan, Montana, Oklahoma, and Pennsylvania. 

The Illinois Department of Public Health (IDPH) reported the state’s first confirmed measles case of 2025, involving an adult in far southern Illinois on April 23. Illinois has had no other reported cases of measles since an outbreak in Chicago in early 2024 that resulted in 67 cases.  

“This first reported case of measles in Illinois in 2025 is a reminder to our Illinois residents that this disease can be prevented with up-to-date vaccination,” said IDPH Director Dr. Sameer Vohra. “With hundreds of cases being reported nationally, we have been working closely with our local public health and health care partners to prepare for any potential measles cases in Illinois. IDPH is urging medical providers to consider a measles diagnosis in patients with consistent symptoms and alert their local health department immediately if they suspect a case.” 

On April 17, the Montana Department of Public Health and Human Services and the Gallatin City-County Health Department (GCCHD) reported Montana’s first cases of measles since 1990. The GCCHD is investigating five confirmed cases of measles. The individuals are children and adults who were exposed to measles while traveling outside of Montana. All five individuals are unvaccinated, or vaccine status is unknown. 

“While it is unfortunate to have cases of measles after 35 years of disease inactivity in Montana, we have been working diligently with our local partners to prepare,” said Dr. Maggie Cook-Shimanek DPHHS public health physician. “We are confident that our public health and clinical partners will work together and address this situation as quickly as possible. It is important for everyone to know their vaccination status and to visit with their health department or health care provider if they are unsure.” 

On April 19, the Louisiana Department of Health confirmed one case of measles in an adult resident of Region 1 (comprised of Jefferson, Orleans, Plaquemines, and St. Bernard parishes). The patient’s exposure to measles appears to be linked to international travel. In 2024, three confirmed travel-associated measles cases were reported in Louisiana, all in the greater New Orleans area. 

On April 18, the Missouri Department of Health and Senior Services confirmed a case of measles in a child of Taney County associated with recent international travel.  

On Friday, the Texas Department of State Health Services (TDSHS) reported that the number of measles cases grew to 6646 in the ongoing largest U.S. outbreak, marking an increase of 22 since April 22. About 1%, or fewer than 10 of the confirmed cases, are estimated to be actively infectious since their rash onset date was less than a week ago. Most of the cases are in children. Sixty-four people have been hospitalized over the course of the outbreak.  Two fatalities in school-aged children who lived in the outbreak area have occurred. The children were not vaccinated and had no known underlying conditions. 

The most recent TDSHS data showed outbreak counties with ongoing measles transmission include Cochran, Dallam, Dawson, Gaines, Garza, Lynn, Lamar, Lubbock, Terry and Yoakum. 

The New Mexico Department of Health (NMDOH) also reported that the state’s case count for measles has risen to 66 as of April 25. While most cases remain in Lea County, the outbreak spread to Eddy, Chaves, and Doña Ana Counties Currently, seven residents are hospitalized. NMDOH recorded the death of one unvaccinated Lea County resident on March 6, the second in the outbreak. 

North America also has two other outbreaks. One in Ontario, Canada, has sickened 925 from mid-October through April 16, The Associated Press reported. And as of April 22, the Mexican state of Chihuahua state has 514 measles cases, according to data from the state health ministry. The World Health Organization has said cases in Mexico are linked to the Texas outbreak.