Measles cases in the United States have reached their highest level in 35 years, marking a dramatic resurgence of a disease that was declared eliminated in the country a quarter-century ago.
New data released July 22 by the Johns Hopkins University shows 2,295 measles cases have been reported nationwide so far this year, surpassing the 2,286 infections recorded during all of 2025 and marking the highest annual total since 1991.
Health experts say the surge has been fueled by declining vaccination rates that have left more communities vulnerable to outbreaks. The milestone comes as state health officials announced a new outbreak in Kent County, Delaware, involving four unvaccinated adult men.
“In communities with pockets of susceptible individuals across a broad age range, measles has been able to take hold, infecting those who are susceptible and spreading rapidly,” William Moss, executive director of the International Vaccine Access Center at Johns Hopkins, said in a news release.
The United States declared measles eliminated in 2000 after recording just 86 cases that year, according to the Centers for Disease Control and Prevention. But a series of outbreaks that began in early 2025, centered initially in Gaines County, Texas, has helped drive the virus’ resurgence.
Why Are Measles Cases on the Rise?
Vaccination for measles has declined in recent years, resulting in a growing number of states no longer reporting rates consistent with herd immunity. Herd immunity occurs when more than 95% of people in a community are vaccinated and most people are protected, even if they cannot get the vaccine themselves, because those around them are immune and cannot spread the disease.
Vaccination coverage among U.S. kindergartners decreased from 95.2% during the 2019–2020 school year to 92.5% in the 2024–2025 school year, well under the threshold necessary for effective herd immunity, according to the CDC.
Outbreaks, like the large one in Texas, often occur within communities with large pockets of unvaccinated people. A small, under-vaccinated Mennonite community was at the center of last year’s largest outbreak, for example.
Declining protections have also been attributed to the growing anti-vaccine movement, which was bolstered by the confirmation of vaccine skeptic Robert F. Kennedy Jr. as health secretary. In addition to making anti-vaccine comments, Kennedy also downplayed pediatric deaths related to measles and touted false cures and preventives, such as the use of vitamin A. During the height of the Texas outbreak, Kennedy encouraged inoculation against measles, pulling back from his previous anti-vaccine messaging.
What Is Measles, and How Do You Get It?
Measles is a highly contagious, vaccine-preventable disease caused by a virus that primarily and most severely afflicts children. According to the World Health Organization, it infects the respiratory tract before spreading throughout the body. It is characterized by high fever, cough, runny nose, watery eyes and rashes or bumps that appear seven to 14 days after exposure.
The virus is one of the most contagious infectious diseases; so contagious, in fact, that 90% of unvaccinated people who are exposed end up contracting it. Additionally, 1 in 5 of those people end up hospitalized, according to the CDC.
The MMR vaccine (measles, mumps and rubella) protects against measles with 97% efficacy, and is typically administered to children as part of the regular vaccine course at ages 12 to 15 months for the first dose and ages 4 to 6 for the second.
Reporting by James Powel and Mary Walrath-Holdridge, USA TODAY / USA TODAY
USA TODAY Network via Reuters Connect
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