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.

Resurgence of Measles

New data released 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.

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.

Vaccination Rates

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.

Original reporting: Las Cruces Sun News (HLL/CB) — read the source article.