When Susan Monarez took the helm of the beleaguered US Centers for Disease Control and Prevention (CDC) in late July, she had her work cut out for her. Public trust in the agency had dropped considerably since the start of the COVID-19 pandemic. And US health secretary Robert F. Kennedy Jr, who oversees the CDC, had called the agency a “cesspool of corruption” that needed to be fundamentally rebuilt.
Less than a month into Monarez’s tenure, US President Donald Trump fired her. She had lost the trust of Kennedy, who only a month earlier had said he had “full confidence” in her ability to lead the agency and that she had “unimpeachable scientific credentials”.
This conflict spilled into public view when each presented their version of events to US senators at separate hearings on Capitol Hill in Washington DC. Monarez was dismissed, she said, for refusing to fire top scientists at the agency or pre-approve vaccine recommendations without first considering the relevant scientific data. Kennedy testified that Monarez had told him that she wasn’t trustworthy, so he ousted her.
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Kennedy had also told Monarez that CDC employees were “killing children and they don’t care”, were “bought by the pharmaceutical industry” and “forced people to wear masks and social distance like a dictatorship”, she testified. These alleged comments came after a deadly shooting at the CDC headquarters in Atlanta, Georgia, soon after she became director. The gunman, who targeted the campus to protest COVID-19 vaccines, killed police officer David Rose and shattered some 150 windows.
The past few months, Monarez says, have included both “the highlights of my professional career” and the “absolute worst days of my life”. In an exclusive interview — her first since she became CDC director — she tells Nature about the consequential decisions that cost her the job and what’s next for public health in a politicized world.
The CDC director is an “inherently political position, but that doesn’t mean that it has to be politically compromised”, says Monarez, who is an immunologist and microbiologist. “The CDC is far too important to just give up on.”
Before our call, you sent me a photo that seems to be of you as a child with your father and siblings sitting on a tractor with a barn in the background. What was that about?
I grew up in rural America, in a family that didn’t have many resources — my dad was a dairy farmer. You live without expecting to have the privileges and material possessions that so many people have. We just knew that you worked hard. You got up early and you treated people with kindness. We lived at or below the poverty line for a long time.
My parents, they’re still alive, thankfully. But they’ve never been wealthy, and they don’t have the advantages of immediate access to high-quality health care, and so I see them still struggling today. When we’re talking in Washington DC, we have to remember that there are millions and millions of Americans like my parents. We can’t leave them behind.
“I am an optimist. I always think that I can work harder so that other people can live better.” —Susan Monarez, former CDC director
Before the CDC, you worked at the Advanced Research Projects Agency for Health (ARPA-H), a government agency supporting high-risk, high-reward biomedical research. How did that work inform your priorities for CDC?
So much of what we built at ARPA-H was free from all of the bureaucratic impediments. We gave ourselves permission to ask: ‘What if we could change the world?’ I wanted to bring that mindset to CDC.
Just eight days into your tenure, there was a deadly shooting at CDC headquarters that terrified many members of your staff. Tell me about that experience.
The first week was probably one of the highlights of my entire professional career — meeting hundreds of CDC employees who wanted to make a difference and change the world. I got on the plane to come back to [Washington] DC. And I finally got WiFi just before we landed, and all these texts had started coming through: ‘Something’s happening here, we’re hearing there’s a shooter.’
It was the most surreal, painful change between this extraordinary enthusiasm of ‘we’re going to change the world with the most amazing people’ to ‘has anyone been killed?’
[As I spoke to more CDC staff,] it looked like most were OK, but highly traumatized, because so many people were literally in the line of fire.
My father — after we lost the farm — became a police officer. It was so near and dear to my heart, the willingness of these police officers to sacrifice themselves. I couldn’t stop thinking about Officer Rose losing his life. It could have been my dad.
This wasn’t an abstract, faraway thing. These were real humans who were targeted with real bullets that were not intended for buildings — they were intended to cause harm.
What do you make of Kennedy’s characterizations of CDC employees, such as his suggestion they have been ‘bought by the pharmaceuticals industry’?
I did not meet a single human that embodied that rhetoric. They could be making a lot more money [in the private sector].
I am worried about the context that we’re placing on our public-health officials, who just want to help people. To contextualize it any other way is to do them such an extraordinary disservice.
How are we going to incentivize our best and our brightest to contribute to public health, which is thankless? And what happens if we don’t?
You also testified that Kennedy had asked you to pre-approve vaccine recommendations that hadn’t yet been made. Was that the main sticking point for you?
And firing scientists without cause. [At CDC, I] had been with selfless, brilliant, amazing people who just wanted to contribute to wellness. We had already started talking about, ‘How do we restore public trust?’ because ‘just trust us’ doesn’t work any more. So it was [against] that backdrop and then being told I had to fire these people without cause that — as a human, I wouldn’t do that. And as a leader, I wouldn’t do that.
And being asked to commit [wholeheartedly] without evidence — I would never do that, as a scientist. You have to gather the right data.
[Emily Hilliard, a spokesperson for Kennedy’s agency, the Department of Health and Human Services, said in a statement to Nature last month that Monarez “acted maliciously to undermine the president’s agenda and was fired as a result”. Kennedy conceded, in remarks to Congress, that he had asked Monarez to fire CDC staff members.]
At least ten states say they can no longer trust the CDC and have formed their own alliances, one on the West Coast and one in the Northeast. What do you make of these efforts?
These states are worried about the people who live in their communities. They’re worried about whether they will be able to help to prevent public-health harms. I understand their concerns. It is a reflection of [how much some people can trust] what’s emanating from the federal government.
Isn’t this in some ways playing directly into what this administration is pushing for — a dismantling of the federal government in favour of states’ rights? Is that compatible with the fundamental principles of public health?
Public health doesn’t respect state boundaries. We do need to find a way to work together. I’ll go back to my own upbringing. The rural community where I grew up could easily be left behind [if access to high-quality healthcare is available in one state but not another] and we don’t want that.
Kennedy has long been open about his views on vaccines and his intention to gut the CDC. What made you interested in heading up the agency?
I am an optimist. I always think that I can work harder so that other people can live better.
I have been in and around government now for 18 years — every administration from [Republican George W.] Bush till now. I’ve always been in a position where I’ve been able to make contributions. We were always marching steadily towards a better world.
I’m less naive now than I was.
What makes you say that?
I’m always going to remain an optimist. That’s just how I live. But whether or not I ever want to go back to the federal government — I just don’t know if I can. I know that there is greatness in health innovation in the United States and around the world. I’ve seen it. And I just don’t ever want to be put in a position where we don’t embrace that — where we hold back, and we don’t have our eyes on a future horizon that allows us all to live better.
The CDC director is a political appointee. Does your experience show that the influence of politics in the director’s role is a foregone conclusion?
It is an inherently political position, but that doesn’t mean that it has to be politically compromised.
I hope [scientific leaders] comport themselves with professionalism, transparency and the highest level of integrity, knowing that when you’re in a position of authority, you have the opportunity to influence millions of lives. And that all of us who are ever privileged enough to be in that position need to be humble, and we need to take our jobs very seriously.
The CDC is far too important to just give up on.
This article is reproduced with permission and was first published on October 2, 2025.
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