The number of measles cases reported across the US this year has climbed to 2,295, the highest annual total since 1991, according to Johns Hopkins University (JHU).

Measles is a highly contagious viral respiratory disease that was declared eliminated in the US in 2000 following a successful mass vaccination campaign. However, cases surged last year, rising more than eightfold from 2024.

“Unvaccinated individuals or those with unknown vaccination status represent almost all reported measles cases,” JHU said in its Wednesday update. “These outcomes are consistent with estimates that two doses of measles vaccine protect 97% of those vaccinated,” it added.

The last time national infection numbers were higher was in 1991, when the US recorded 9,643 cases, according to data from the US Centers for Disease Control and Prevention (CDC).

The largest outbreaks this year were centered in South Carolina and Utah, following a major multistate outbreak in West Texas that spread into neighboring New Mexico and other states in 2025, according to JHU.

“That tells us this has been years of undervaccination in some communities,” William Moss, a professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health, told the Washington Post.

“It’s very frustrating. This is a reflection that we have been unable to stop measles virus transmission in this country,” he added.

US Health Secretary Robert F. Kennedy Jr., a longtime vaccine skeptic, recommended that people receive the measles-mumps-rubella (MMR) vaccine following the Texas outbreak. He did, however, stress that “the decision to vaccinate is a personal one.”

President Donald Trump, speaking to ABC News last year, said he recommended the MMR vaccine. “I recommend it. Yeah… Do I mandate it? No,” he said.

Vaccine hesitancy is on the rise in the US and globally, with experts attributing the trend to misinformation spread during the Covid-19 pandemic and protests against vaccine mandates.