U.S. Health and Human Services Secretary Robert F. Kennedy Jr. told vaccine-skeptic activists they have a strong ally in the White House during a conference in Washington on September 17.

Kennedy delivered the keynote address at a conference hosted by Children’s Health Defense, an organization he previously chaired. It was his first appearance at the group’s conference since becoming health secretary.

During the speech, Kennedy said the Trump administration was working to change federal vaccine policies and urged attendees to remain patient as the government moves through legal and administrative procedures. 

Kennedy highlighted efforts to reconsider aspects of federal vaccine guidance and said the administration was examining questions surrounding vaccine safety and long-term health outcomes.

He also repeated claims about possible vaccine-related health effects. Medical experts have disputed several of these claims, noting that an event occurring after vaccination does not by itself establish that a vaccine caused it. 

The speech came as the United States faces a significant measles outbreak. Pennsylvania has reported four measles-associated deaths this year, adding urgency to the ongoing debate over childhood vaccination and public health policy. 

Kennedy previously took an unpaid leave from Children’s Health Defense while pursuing his presidential campaign and later resigned from his positions before becoming HHS secretary. His appearance at the conference has drawn attention because of his current role as the country’s top federal health official.