The Trump administration’s new global health strategy, released last month, lists its most important goal as outbreak prevention and response, both to protect Americans and to safeguard the economy.

Containing the Ebola outbreak in West Africa a decade ago cost the United States $5.4 billion globally and more than $70 million domestically, the strategy report notes, adding, “As we have unfortunately seen all too frequently, an outbreak anywhere in the world can quickly become a threat to Americans.”

Yet, the freeze on America’s foreign aid in January disrupted many programs that extinguished outbreaks. Citing “waste, fraud and abuse” at federal agencies, the administration also laid off thousands of scientists, including many who worked on preventing and containing infectious diseases.

Since the spring, the administration has restored some programs and rehired some scientists. And on Saturday, it rescinded the layoffs of hundreds of infectious disease experts fired in error just a day earlier.

But many others placed on administrative leave are still awaiting word on their next career steps.

The Department of Health and Human Services “has preserved the expertise necessary for pandemic preparedness, and our agency remains committed to infectious disease research, surveillance and response,” a spokesman said.

“We continue to support this critical public health priority through ongoing monitoring, vaccine development and partnerships at home and abroad,” he added.

But some experts worry that the loss of this particular kind of expertise leaves Americans vulnerable to new pandemic threats. “The diseases aren’t going away,” said Dr. Lorin Warnick, dean of Cornell’s College of Veterinary Medicine. “The risks are even higher now.”

We spoke with four well-regarded infectious disease scientists about their work, their lives now and the state of the nation’s pandemic preparedness.

‘Abrupt Demonization’

Three years ago, Sarah Paige led a team at the U.S. Agency for International Development that helped to contain an Ebola outbreak in Uganda. Jobless since the collapse of the agency, Dr. Paige, 51, is now freelancing for a for-profit company reviewing research proposals, even as Ebola is again spreading in the Democratic Republic of Congo.

“I just wanted to do something and have meetings, because in the afternoons I get so lonely,” she said recently.

Dr. Paige studies the links between people, the environment and diseases.

Early in her global health career, at Kibale National Park in Uganda, she saw baboons break into people’s kitchens and red colobus monkeys terrorize children and dogs. Witnessing the interactions, she was struck by the realization that diseases can jump from people to animals, not just the other way around.

Several years after completing a doctoral degree on those relationships, she applied to work at U.S.A.I.D. During the virtual job interview, agency officials unexpectedly asked her to turn on her camera. It was 9 p.m., and Dr. Paige appeared onscreen, mosquitoes and other insects swirling around her headlamp. She got the job.

In September 2022, she led the agency’s response to Ebola in Uganda, working closely with other American agencies. Dr. Wilberforce Owembabazi Ndyanabo, her colleague at the time, said she was particularly adept at “navigating the gymnastics” of quickly mobilizing people and funds.

But the success came at a cost, Dr. Paige said. She developed early-stage liver disease, high blood pressure and shingles, and returned home.

Last January, she went back to U.S.A.I.D., convinced she would stay there for the rest of her career. But just weeks later, the Trump administration began dismantling the agency. Dr. Paige’s job, and the agency, dissolved on July 1. She still struggles, she said, with what she sees as “the abrupt demonization of everybody” who worked there.

And she worried that the nation was even less equipped to cope with a pandemic than it was before Covid-19. The next large outbreak, whatever it turns out to be, “is getting closer,” she said. But with the dismantling of public health structures and rising vaccine hesitancy, “we’re just not prepared,” she said.

Dr. Paige’s husband, a chef, can support the family. But the sudden loss of her work, especially as Ebola rages on, has plunged her into a deep depression, she said.

To keep busy, she volunteers at an animal shelter and takes long walks with her dog. But she feels, she said, as if she were “walking through mud.”

An H.I.V. Bulwark

Dr. Jonathan Mermin fed the five chickens in his backyard, collected and washed their eggs, baked bread, and dried grapes as a snack for his wife.

It was a glorious day in May in Atlanta. But his daily tasks were far different from what they were six weeks earlier, when he was overseeing the Centers for Disease Control and Prevention’s work to contain H.I.V. and other sexually transmitted diseases.

In April, Dr. Mermin, 60, known as Jono to friends and colleagues, was placed on administrative leave and reassigned to the Indian Health Service. He is still waiting to hear what he is supposed to work on. The division of H.I.V. prevention, part of the center he directed, was dismantled and then restored, but the administration is once again preparing to shut it down.

If Congress does not save the division, he said, “we won’t be able to detect outbreaks, and we won’t be able to respond to them effectively, putting more people at risk for getting H.I.V.”

Dr. Mermin has kept in close contact with his former colleagues and employees, and plans to find another job. Still, he said, he is dismayed at having to leave the C.D.C.

He has spent nearly his entire career at the agency, staying on as a civilian after retiring last year from the Commissioned Corps of the U.S. Public Health Service as a two-star rear admiral.

During the first Trump administration, Dr. Mermin was instrumental in shaping the strategy called Ending the H.I.V. Epidemic, which was widely lauded as a success.

He was “not political in any sense,” said Adm. Brett Giroir, an assistant health secretary during that administration.

Under Dr. Mermin’s leadership, new H.I.V. infections in the nation dropped by 36 percent, and resurgent sexually transmitted infections showed the first signs of a plateau nationwide.

He also directed health departments to spend the bulk of their money on prevention. It was “a very precise and scientific and logical approach” to make the biggest impact for the least money, said Greg Millett, who worked as a deputy for the Office of National AIDS Policy in the Obama White House.

Now, however, Dr. Mermin is spending his days at home with his chickens and his misbehaving cat. The fate of the H.I.V. division hangs in the balance, and he worries that lawmakers may not realize its importance. “What if no one cares?” he said.

Animal Threats

The administration’s new strategy notes that three-quarters of emerging infectious diseases, like bird flu, spread from animals. To fully contend with such threats, scientists need more than a medical degree. They need experience with animals, a familiarity with diseases and a deep understanding of public health.

Dr. Stéphie-Anne Dulièpre checked every box when she arrived at U.S.A.I.D. in October 2024. She was a licensed veterinarian, had worked at the Agriculture Department, and had studied public health at Johns Hopkins University.

But she lost her position only a few months later when U.S.A.I.D. was shuttered. “It’s devastating because I have barely scratched the surface of what I can do with all of my skills,” she said.

Dr. Dulièpre lived in Haiti until age 11. She said she grew up alongside dogs, goats and chickens; brought home “insects upon insects” to study; and could tame the most feral cat. Her deep connection to animals eventually led her to study veterinary medicine at Cornell, even though only about 2 percent of veterinarians identify as Black.

“The typical veterinarian is not a Black woman, let me just say that,” she said. “I had no one that I knew that took the path ahead of me.”

At U.S.A.I.D., Dr. Dulièpre’s skills made her an asset for several projects on emerging zoonotic diseases, recalled Stephanie Martz, her supervisor at the time.

One project in Dong Nai Province, Vietnam, involved helping farmers care for captive wildlife. Visiting staff members had to stay at a hostel that had a tarantula living behind the toilet. The team was certain she would back out of the project when she heard about the spider.

“But she was like, ‘No, sign me up, I’m going to go,’” Ms. Martz said. “We knew she was going to be a good fit.”

Since U.S.A.I.D.’s collapse, Dr. Dulièpre has been working as a veterinarian to pay bills and $125,000 she still owes in student loans.

“I’m still searching,” she said, “looking around to see where else I can use these skills.”

The Vaccine Specialist

Dr. Emily Erbelding’s undoing may have begun during the coronavirus pandemic.

An infectious disease expert at the National Institutes of Health, she was a leader of Operation Warp Speed, President Trump’s project to rapidly develop Covid vaccines during his first term. But the division she led at the N.I.H. also oversaw a grant to EcoHealth Alliance that became a central focus of the controversy over the origins of the coronavirus.

The grant was funded after a peer review, and she canceled it when problems arose. Still, along with Dr. Anthony Fauci, she has borne much of the blame, and her involvement may have led to her being ousted from the agency in April, she said.

Immediately after Mr. Trump took office in January, the spreadsheets began arriving at the N.I.H. One executive order demanded that studies that collected gender identity information either drop that aspect or cease altogether.

Then came orders to terminate grants intended to increase diversity, equity and inclusion; awards to Columbia University and scientists in South Africa; and funding for foreign collaborators.

“It made me heartsick to look at the spreadsheets,” Dr. Erbelding said.

Employees were crying in her office or in the bathroom almost every day, she said, adding, “There’s just a lot of idealism that’s being crushed.”

Dr. Erbelding became focused on infectious diseases while in medical school at Indiana University. A fellowship at Johns Hopkins coincided with dual epidemics of H.I.V. and syphilis in Baltimore.

In 2010, she became deputy director of the N.I.H.’s AIDS division, just as the rollout of H.I.V. drugs was expanding.

She later led a division that dealt with other infectious diseases, including those that may cause pandemics, helping to develop vaccines against them.

Then came an actual pandemic. Dr. Erbelding was there from the first planning meeting for a vaccine in January 2020. She made sure the clinical trials included specific populations — children, minority groups, people with H.I.V.

If there were another pandemic, she said, the thinned-out federal agencies might not be able to support another effort like Warp Speed.

“You’re destroying something with these draconian cuts that took years to build,” she said. “It can’t be rebuilt as fast as it was taken down.”

At 64, she is not ready to stop working. She rows in Baltimore three or four times a week when the weather cooperates, and regularly competes in regattas, returning with bloody blisters on her hands.

Focusing on her stroke “cleanses the mind really nicely,” she said. “You can forget about all the ills of the world.”