During a three-hour Senate hearing on Wednesday, Susan Monarez, Ph.D., discussed her brief tenure as head of the Centers for Disease Control and Prevention (CDC) and her falling out with her boss, Department of Health and Human Services (HHS) Secretary Robert F. Kennedy Jr. Senators also questioned Debra Houry, M.D., MPH, who resigned as the CDC’s former chief medical officer in protest of Monarez’ departure and the changes at the public health agency.
Senator Bill Cassidy, M.D. (R-LA), chair of the Senate Health, Education, Labor, and Pensions (HELP) Committee, scheduled the hearing following the high-profile departures from the CDC and his desire to follow President Donald Trump’s call for radical transparency. He said he intends to invite current HHS officials to an upcoming hearing to hear their version of what happened.
Earlier this month Kennedy appeared before the Senate Finance Committee to provide his account of the leadership changes at the CDC, including what led to Monarez’s exit only 29 days after her Senate confirmation. He claims he lost confidence in her leadership during an August 25 meeting when he asked her whether she was a trustworthy person and Monarez said no. Her termination triggered the resignations of four senior CDC officials.
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In his opening remarks, Cassidy said as a doctor, it’s vital that physicians can rely on the CDC for clear guidance to make informed decisions to protect their patients. As a Senator, he discussed his concern that Monarez, the first CDC director to be confirmed by the Senate, was let go from the position less than a month after every Republican voted in favor of her appointment. “What happened,” Cassidy asked. “Did we fail? Was there something we should have done differently?”
While it may be impossible to learn who is telling the truth, Cassidy said the hearing is an initial step to find out why top CDC leaders were fired or resigned before they could be fired. Turmoil at the top of the nation’s top public health agency is not good for the health of the American people,” he said. “This is not about politics; this is about protecting children’s health and rebuilding trust in institutions. I want President Trump to have the best CDC in our nation’s history. I want to work with the President to fulfill his campaign promise to reform the CDC and Make America Healthy Again.”
Monarez on her fall out with Kennedy
The long-time microbiologist and immunologist said that the events leading to her dismissal began weeks before August 25, including the removal of experts from working groups of the Advisory Committee on Immunization Practices (ACIP); a gunman, driven by vaccine distrust, firing hundreds of rounds into the CDC headquarters in Atlanta, killing Officer David Rose; and a directive from Kennedy’s office that she would need prior approval from political staff for CDC policy and personnel decisions.
According to Monarez, Kennedy informed her that the childhood vaccine schedule would be changing in September, and she needed to be on board. He demanded on August 25 that she approve in advance every ACIP recommendation regardless of the scientific evidence, and that she dismiss career officials responsible for vaccine policy without cause. If she was unwilling to do both, he told her she should resign. Monarez said she couldn’t preapprove recommendations without reviewing the evidence and she had no basis to fire scientific experts.
“For three decades, I have worked at the intersection of public health, science, and technology innovation—always challenging the status quo and welcoming the change that comes from research and discovery. Even under pressure, I could not replace evidence with ideology or compromise my integrity. Vaccine policy must be guided by credible data, not predetermined outcomes,” she said.
Kennedy said he could not trust her because she refused to commit to approving vaccine recommendations without evidence and fire career officials without cause. “I told the Secretary that if he believed he could not trust me, he could fire me,” she said.
Houry on her resignation, the new direction of CDC
Houry, who spent a decade at the CDC, most recently as the chief medical officer and deputy director for program and science, said she served with six CDC directors through four different administrations, including the first Trump administration. She carried out the priorities of each administration and when priorities changed with each one, she said decisions were always made with considerations of the scientific evidence. That has changed, she said.
“I resigned because CDC leaders were reduced to rubber stamps, supporting policies not based in science and putting American lives at risk,” Houry said. “Secretary Kennedy censored CDC science politicized its processes, and stripped leaders of independence. I could not in good conscience remain under those conditions.”
Monarez, Houry on concerns with ACIP committee, upcoming recommendations
Monarez and Houry testified a day before the newly formed ACIP is scheduled to meet to make recommendations on vaccines for measles. mumps, rubella, and varicella (MMRV); Hepatitis B, and COVID-19.
The composition of the new board has raised concerns from the medical community, Monarez noted. Based on what she observed, Monarez said there is a real risk that the board could restrict access to vaccines for children and others in need without rigorous scientific review.
“The question before us is whether we will keep faith with our children and grandchildren—ensuring they remain safe from the diseases we fought so hard to defeat: polio, measles, diphtheria, whooping cough, and many others,” she said. “Undoing that progress would not only be reckless—it would betray every family that trusts us to protect their health.”
Houry said the removal and replacement of members of ACIP is an example of how erosion in the public health institutions threaten the lives of Americans. “Under Secretary Kennedy, the committee has been replaced with known critics of vaccines and operates under decreased transparency, with a willful refusal to follow established scientific and decision-making procedures,” she said. ”Process matters because trust matters. If people believe outcomes are predetermined, or that recommendations are slanted by ideology rather than scientific data, they are less likely to accept even well-supported recommendations. Sadly, this is the path we are on.”
Meanwhile, she said, the CDC’s work has been curtailed. The agency has not received permission to restart flu vaccine campaigns for this upcoming season despite the fact that 270 influenza-associated pediatric deaths occurred during the 2024-2025 season—ithe highest number of pediatric deaths ever recorded in a non-pandemic year since pediatric flu deaths became reportable in 2004. Among children who were eligible for the flu vaccine and with known vaccine status, 90 percent of reported pediatric deaths this season were not fully vaccinated.
“Silencing science-based campaigns does not change the reality of flu—it only ensures more preventable deaths,” Houry said.
Monarez, Houry on the future of public health
Monarez told the committee she fears that the changes being made will lead to the return of preventable diseases and children will be harmed. “I worry about the ramifications for those children in illness and in death. I worry about our school systems. I worry about our medical institutions having to take care of sick kids that could have been prevented by effective and safe vaccines. I worry about the future of trust in public health,” she said.
America's progress in health is one of the greatest success stories in history, Houry said. “A century and a half ago, life expectancy hovered around 39 years. Today it is nearly double that because of vaccinations, safer food and water, smoking cessation, and through the quiet, steady work of public health in every state and county across the country,” she said.
Houry said she worries the country will backslide. Public health officials are already seeing childhood vaccination rates decrease, leaving children at risk for preventable illnesses, such as outbreaks, as well as children and adults vulnerable to the next type of pandemic, she said. “With some of the staff cuts we have faced, we have less ready responders,” she said. “We have less visibility into global pathogens at this time as well.”
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