U.S. Health and Human Services Secretary Robert F. Kennedy Jr. testified Thursday before the Senate Finance Committee, where lawmakers pressed him on recent upheaval at federal health agencies and his approach to vaccine policy.

The hearing, convened to examine Kennedy’s “Make America Healthy Again” initiative, quickly turned to questions about staff departures and budget changes at the Centers for Disease Control and Prevention (CDC). The Trump administration last week dismissed CDC Director Susan Monarez less than a month after her appointment, prompting several senior officials to resign in protest.

In an opinion piece published Thursday in The Wall Street Journal, Monarez alleged that Kennedy sought to diminish public health safeguards. She wrote that she had been directed to preapprove recommendations from a newly restructured vaccine advisory panel, which she said included members who had previously voiced skepticism of vaccines.

Sen. Ron Wyden (D-Ore.), the committee’s ranking Democrat, said Kennedy “must answer to the public and their representatives about the chaos, confusion, and harm his actions are inflicting on American families.”

Republican members also signaled concerns. Sen. Bill Cassidy (R-La.), a physician and supporter of vaccines, is expected to scrutinize Kennedy’s policies. Sen. Thom Tillis (R-N.C.) told reporters he wanted to hear directly from the secretary, saying Kennedy must “reconcile what he said during his confirmation process with what we’ve seen over the past few months, particularly on vaccine policy.”

Kennedy, a longtime critic of vaccines, announced in May that COVID-19 vaccines would no longer be recommended for healthy children and pregnant women—a decision opposed by numerous medical and public health organizations.

The hearing highlighted the growing debate over the administration’s public health direction, particularly in light of leadership changes at the CDC and broader questions about how the nation prepares for and responds to disease threats.