Michael Liu grew up in Toronto, Canada, then moved to the U.S. for college and medical school because, to him, America was the premiere destination for fulfilling his aspirations to become a physician and researcher.

"You know, in chase of the American Dream, and understanding all the opportunities — that was such a draw for me," says Liu, who attended Harvard University. He is now 28 and has deep personal and professional roots in Boston, where he's an internal medicine resident at Mass General Brigham.

But this spring, he was shaken by the Trump administration's cuts to scientific research at the National Institutes of Health and staff at the Department of Health and Human Services. "That was a really striking moment for me," Liu says. "It made me question where, professionally, it made most sense for me. I still have strong connections to Toronto and mentors."

Then, in September, Liu was doing rounds with two doctors from Mexico and Costa Rica, when the administration hiked fees nearly 30 fold for H1B visas, which are for highly trained professionals, to $100,000. He watched his colleagues' tearful reactions to the sudden uncertainty that thrust on their careers, knowing that employers like hospital systems are unlikely to be able to afford to pay for such dramatic increases.

"It was terrible to see," Liu says. He has a green card, having married an American citizen earlier this year. But, he says, the Trump administration's actions affect him.

"It feels like my contribution is — just because I was not born in this country — less valued," Liu says. "I really hadn't thought so deeply about going back home before, but definitely it's been much more top of mind."

A rural workforce

Immigrants make up about a quarter of all the country's doctors, and the U.S. health care system depends heavily on them. There are roughly 325,000 physicians — not including nurses or other critical health care workers — living and working in the U.S., who were born and trained elsewhere.

In rural communities, and in some subspecialties of medicine, the reliance on immigrant physicians runs much higher. In primary care and specialties like oncology, for example, foreign-born doctors account for about half of the workforce.

Meanwhile, health care is already burdened by retirements and burnout. Many experts say recent immigration and health policies are only making it harder — and less appealing — for foreign-born talent to augment the short-staffed American health system.

"This is a real pivotal moment right now where decades of progress could be at risk," says Dr. Julie Gralow, chief medical officer at the American Society of Clinical Oncology.

She says policies defunding everything from scientific research to public health have damaged the U.S.'s reputation to the point where she hears from hospitals and universities that top international talent are no longer interested in coming to America. "Up until this year, it was a dream — a wish! — that you could get a job and you could come to the U.S. And now nobody wants to come."

Gralow says, meanwhile, other countries like China, Denmark, Germany and Australia are taking advantage by recruiting international talent away from the U.S. — including American-born doctors and medical researchers — by promising stable grant funding and state-of-the-art facilities abroad.

American patients will feel the rippling impact from that, Gralow says, for generations.

Immigrant physicians have historically found jobs in U.S. communities with serious health care staff shortages to begin with, so those places also stand to see more impact from curtailed international hiring, says Michael Liu, the Boston medical resident.

He points to his own recent co-authored research in JAMA estimating that 11,000 doctors, or roughly 1% of the country's physicians, currently have H1B visas. "That might seem like a small number, but this percentage varied widely across geographies," he said, and they tend to congregate in the least-resourced areas, reaching up to 40% of physicians in some communities.

"High poverty counties had a four times higher prevalence of H1B physicians; we also saw that same pattern in rural communities," he says. (Many physicians and physician residents may have different kinds of visas, such as J1Bs, and others.)

Groups like the American Medical Association have asked the administration to exempt physicians from the new H1B fees. HHS did not respond to requests seeking comment about recent visa policies and health care workers, though some opposition has seemingly softened the president's position.

A history of immigration

For the past six decades, immigrants have contributed heavily to the U.S.'s reputation as the undisputed world leader in health research and practice. In pay and prestige, the U.S. has been unparalleled, helping attract the world's best talent — at the expense of their home countries.

That began in 1965, during a period of expanding federal investment in public health and scientific research, spurred by international competition and fueled by Cold War rivalries over events like the Soviet launch of Sputnik. That year, Medicare and Medicaid were created, and with them, sudden demand for doctors, says Eram Alam, a professor of science history at Harvard.

"Overnight, you have 25 million — approximately — people who can now access health care services," Alam says. Passage that year of the Hart-Celler Immigration and Nationality Act opened U.S. borders to doctors and other people with in-demand skills, says Alam, who recently published a book, The Care of Foreigners, about the history of immigrant physicians in the US.

Over the following decade, the U.S. granted visas to 75,000 physicians, and by 1975, roughly 45% of all U.S. doctors were immigrants, Alam says. The U.S.'s first-rate reputation allowed it to attract more physician talent than America could educate and train: "There were more immigrant physicians that were entering the labor force per year than there were U.S. trained physicians that were joining," she says.

Now, Alam says, the U.S. is undoing a lot of that, as it dismantles its global leadership role in medicine and science, and narrows its borders.