Health and Human Services Secretary Robert F. Kennedy Jr. said Sunday that parents should get their children vaccinated against measles, as the United States records its highest number of cases in 35 years.

Speaking on CNN's "State of the Union," Kennedy was asked by host Dana Bash, with the school year approaching, whether he would tell parents who have not vaccinated their children that they should do so because the vaccine is safe.

"We tell people ... that parents should get their children vaccinated for measles," Kennedy said. "A measles vaccine is effective. It stops measles in about 97% of the cases. People should get vaccinated."

Kennedy also said, "I've never questioned the efficacy of the MMR vaccine."

Kennedy is a longtime critic of vaccine policy who founded Children's Health Defense, an anti-vaccine advocacy group. He has generally acknowledged that the MMR vaccine prevents measles but has repeatedly raised concerns about vaccine safety and has said the decision to vaccinate should be a personal one.

The measles, mumps and rubella vaccine is about 97% effective at preventing measles after two doses, according to the Centers for Disease Control and Prevention.

The comments came as measles spreads at levels not seen in decades. The CDC had recorded 2,371 confirmed cases as of July 30, surpassing last year's total and making 2026 the worst year for the disease since 1991. Cases have been reported in 45 states, and about 93% of those infected were unvaccinated. Officials have warned the country could lose its measles-elimination status this fall.

The surge has been driven by large outbreaks in several states, including South Carolina, Utah and Arizona, with Pennsylvania among the latest hot spots. Measles was declared eliminated in the United States in 2000, and public health officials have warned the country could lose that status this year. The Pan American Health Organization is expected to decide in the fall.

Measles can cause serious complications, including pneumonia and swelling of the brain, and can be fatal. Two unvaccinated children died during a 2025 outbreak in West Texas, the first measles deaths in the United States in a decade.

Kennedy first publicly urged people to get the measles vaccine in April 2025, during a deadly outbreak in West Texas.