The ex-chief of the US disease prevention agency told senators Wednesday she was fired for refusing to approve changes to childhood vaccine schedules not backed by scientific evidence, as the Trump administration moves to dismantle longstanding health policy.
The high-profile testimony follows last month's abrupt ouster of the Centers for Disease Control and Prevention head Susan Monarez, who told lawmakers on the Senate Health Committee that US Health Secretary Robert F. Kennedy Jr. also demanded she fire career scientists from the agency without cause.
"Even under pressure I could not replace evidence with ideology, or compromise my integrity," she told the panel.
"Vaccine policy must be guided by credible data, not predetermined outcomes."
The testimony comes a day before a highly anticipated meeting of the Advisory Committee on Immunization Practices -- a body Kennedy has dramatically revamped, firing all of its members and replacing them with figures whose views mirror his own vaccine skepticism.
Monarez said Kennedy had demanded she agree to rubber-stamp every recommendation that committee makes to the CDC.
She was fired less than a month after senators had voted to confirm her with unanimous support from Republican lawmakers.
Her testimony contradicts what Kennedy had told the Senate Finance Committee. He insisted he had only requested she keep an open mind and said that she ultimately had not been "trustworthy."
Under questioning from Republican Senate health committee chair Bill Cassidy -- a physician who continues to vouch for the safety of vaccines -- Monarez said she told Kennedy she "would be open" to childhood vaccine schedule shifts if there were solid scientific data to justify them.
But Kennedy "did not have any data or science to point to," she said.
"To be clear, he said there was not science or data" but he "still expected you to change this?" Cassidy asked.
"Correct," Monarez responded.
- 'Censored' science -
Monarez's ouster was followed by the departure of several senior CDC officials from the body.
Former CDC chief medical officer Debra Houry also testified Wednesday, and said Kennedy "censored CDC science, politicized its processes and stripped leaders of independence."
"I could not in good conscience remain under those conditions."
Senator Angela Alsobrooks, a Democrat, later asked Houry if she believed Kennedy was "incompetent and dangerous to the American people's health."
Houry was uncompromising in her response: "Seeing what he has asked our scientists to do and to compromise our integrity, and the children that have died under his watch, I think he should resign."
In 2025, the United States experienced its worst measles outbreak in more than 30 years, with more than 1,400 total confirmed cases and three deaths, including two young children.
Asked by Republican Susan Collins what the public health implications might be if major CDC decisions come from politicized ideology rather than hard science, Monarez said it could move the US into "a very dangerous place in public health."
"These are very important, highly technical discussions that have life-saving implications for our children and others who need vaccines."
Vaccines are safe and effective, according to the overwhelming consensus of the scientific community, but critics say the Trump administration has gone out of its way to sow doubt about them.
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