WASHINGTON (AP) — U.S. Health Secretary Robert F. Kennedy Jr. came under pointed bipartisan questioning at a rancorous Senate committee on Thursday, about — among other things — turmoil at federal health agencies and efforts to pull back recommendations for COVID-19 vaccinations.

Kennedy’s exchanges with Democratic senators on the panel repeatedly devolved into shouting, from both sides.

But some Republican senators also expressed unease with his changes to COVID-19 policies.

The GOP senators noted Kennedy said President Donald Trump deserved a Nobel Prize for the 2020 Operation Warp Speed initiative to quickly develop mRNA COVID-19 vaccines, but that he also attacked the safety and continued use of those shots.

“I can’t tell where you are on Operation Warp Speed,” said Republican North Carolina Sen. Thom Tillis.

Tillis and others asked him why the director of the Centers for Disease Control and Prevention was fired last week, less than a month into her tenure.

Kennedy said she was dishonest, and that CDC leaders who left the agency last week in support of her deserved to be fired.

He also criticized CDC recommendations during the COVID-19 pandemic tied to lockdowns and masking policies, and claimed — wrongly — that they “failed to do anything about the disease itself.”

“The people who at CDC who oversaw that process, who put masks on our children, who closed our schools, are the people who will be leaving,” Kennedy said. He later said they deserved to be fired for not doing enough to control chronic disease.

The Senate Finance Committee had called Kennedy to a hearing about his plans to “Make America Healthy Again,” but Democratic senators pressed Kennedy on his actions around vaccines.

Sen. Ron Wyden of Oregon said Kennedy had “stacked the deck” of a vaccines committee, replacing scientists with “skeptics and conspiracy theorists.”

“Clearly you have an agenda,” said Sen. Raphael Warnock, of Georgia. “It is a threat to the public health of the American people. It’s clear that you are carrying out your extremist beliefs.”

Last week, when the Trump administration fired the CDC’s director less than a month into her tenure. Several top CDC leaders resigned in protect, leaving the agency in turmoil.

The ousted director, Susan Monarez, wrote in The Wall Street Journal on Thursday that Kennedy was trying to weaken public health protections.

“I was told to preapprove the recommendations of a vaccine advisory panel newly filled with people who have publicly expressed antivaccine rhetoric,” Monarez wrote. “It is imperative that the panel’s recommendations aren’t rubber-stamped but instead are rigorously and scientifically reviewed before being accepted or rejected.”

Kennedy told senators he didn’t make such an ultimatum, though he did concede that he ordered Monarez to fire career CDC scientists.

Republicans including Sen. Bill Cassidy of Louisiana, a physician and vaccines supporter, are also likely to press Kennedy.

Asked if he has confidence in the health secretary, North Carolina Sen. Thom Tillis, a Republican on the committee, said he wants to hear from Kennedy in person.

“He’s got to reconcile what he said during his confirmation process with what we’ve seen over the past few months, particularly on vaccine policy,” Tillis said.

In May, Kennedy — a longtime leader in the anti-vaccine movement — announced COVID-19 vaccines would no longer be recommended for healthy children and pregnant women, a move opposed by medical and public health groups.

In June, he abruptly fired a panel of experts that had been advising the government on vaccine policy. He replaced them with a handpicked group that included several vaccine skeptics, and then shut the door to several doctors groups that had long helped form the committee’s recommendations.

A number of medical groups say Kennedy can’t be counted on to make decisions based on robust medical evidence. In a statement Wednesday, the Infectious Diseases Society of America and 20 other medical and public health organizations issued a joint statement calling on Kennedy to resign.

“Our country needs leadership that will promote open, honest dialogue, not disregard decades of lifesaving science, spread misinformation, reverse medical progress and decimate programs that keep us safe,” the statement said.

Many of the nation’s leading public health and medical societies, including the American Medical Association, American Public Health Association and the American Academy of Pediatrics have decried Kennedy’s policies and warn they will drive up rates of vaccine-preventable diseases.