The Supreme Court’s decision allowing the third iteration of President Trump’s travel ban to become permanent immigration policy could have far-reaching effects on the health care system because of a little-appreciated fact: That system relies heavily on foreigners, including foreigners from the list of seven banned countries.

In a 5-4 decision Tuesday, the court upheld the current version of the travel ban — which means the administration can refuse some immigrants and visa holders from Iran, Libya, North Korea, Somalia, Syria, Venezuela, and Yemen entry to the US. This means would-be doctors, nurses, and home care aides (or their family members) from these countries will have a hard time entering the US, even when they qualify for the administration’s waiver program.

In many ways, the health system is already stretched too thin, with scarcely enough people spread evenly across the country to do many difficult jobs. And a letter from the American Medical Association to the Secretary of Homeland Security on an earlier Trump travel ban spelled out this immigration policy could make the situation worse by "creating unintended consequences."

Waivers are “golden tickets” from the State Department that allow citizens from banned countries to apply for entry to the US, and immigration officials decide it’s in America’s best interest to let them up. But they’ve also been very difficult to obtain, as Mohammed Al-Awadhi, a Yemen-born doctor practicing in Arkansas, learned when he tried to get a waiver for his Yemeni wife, according to the Washington Post. She had been approved for a visa in December, then rejected following Trump’s third travel ban.

The current iteration of the ban is a watered-down version of the original, which came into effect by executive order in January 2017. As Vox’s Dara Lind explained, it was designed to be “court proof,” and it targets fewer than 70,000 people — less than half of the original ban’s reach. But when you consider how much of the health care workforce is made up of immigrants like Al-Awadhi, the effects of this ban on health professionals, their families, and the health system look chilling.

Immigrants make up 22 percent of the health workforce and 30 percent of doctors and surgeons in the US

Walk into any hospital, but especially rural hospitals, in the US, and you’ll notice something: Many of the people taking care of you probably weren’t born here. Health care in this country is strikingly international, with the largest proportion of foreign-born and foreign-trained workers of any US industry.

According to 2015 data from the Migration Policy Institute, the US medical profession is particularly reliant on immigrant doctors. Of all the active physicians and surgeons, fully 30 percent are immigrants.

“India, China, Philippines, Korea, and Pakistan are the top five origin groups for physicians and surgeons,” said Jeanne Batalova, a senior policy analyst and demographer at MPI.

Iran and Syria, two of the countries whose citizens are no longer allowed entry to the US, are the sixth and 10th largest contributors, respectively. “So we’re talking about substantial representation from these countries [in the doctor workforce] here,” she added. The ban on these people will likely be felt at hospitals and clinics across the nation.

The contributions immigrant doctors make to medical care start early on when they become residents, before being funneled through training and into jobs. A data analysis performed by the Robert Graham Center showed that residents from the seven countries made up 5.7 percent of all international medical graduates in 2015, said Stan Kozakowski, director of medical education for the American Academy of Family Physicians. (Some data sets look at the country of origin for doctors, others at where they obtained their medical degree — and doctors who trained outside of the US are called “international medical graduates.”)

That’s not a huge number, Kozakowski added, but it’s sizable enough. “And if you add in the countries that [could be] tossed in as possible expansions of the ban — Pakistan, Saudi Arabia, Lebanon, and Egypt — that number goes up to 16.7 percent.”

Foreign-trained doctors make up more than 50 percent of geriatric medicine specialists and nearly 40 percent of internal medicine doctors

When you break it down by medical specialty, foreign-trained doctors do a disproportionate amount of the work in certain areas. They make up more than 50 percent of geriatric medicine doctors, almost half of nephrologists (or kidney doctors), nearly 40 percent of internal medicine doctors, and nearly a quarter of family medicine physicians, according to data from the Association of American Medical Colleges.

Compared with US-trained physicians, foreign doctors are also more likely to practice in areas where there are doctor shortages — in particular, in rural areas. (Many enter the US on visas that allowed them to stay if they work in an underserved area for three years after residency.) They’re also more likely to serve poor patients on Medicaid, the Centers for Disease Control and Prevention has found.

“Doctors — especially in rural areas that were the key constituency that supports Trump — tend to be foreign-born,” said Nicole Smith, a chief economist at the Georgetown University Center on Education and the Workforce. “The old adage that foreigners are doing the work no Americans want to do even applies to medical doctors.”

A 2017 study in BMJ revealed another twist: Patients treated by foreign-trained doctors had better mortality outcomes than those treated by doctors who went through American medical schools. The study authors suggested for foreign docs’ over-performance might be explained by the fact that they “represent some of the best physicians in their country of origin” and had to overcome intense competition and years of training to finally practice in the US.

Health care currently has the largest proportion of foreign-born and foreign-trained workers in the country of any industry

The foreigners in health care don’t just practice medicine, though. The nursing profession is also overstretched and facing projected shortfalls in the coming years, and has come to count on immigrants. As of 2015, some 20 percent of the health care support staff — including nurses and home aides — were immigrants.

Besides work at the bedside, the research immigrants do in labs across the country is also under threat. One Syrian medical researcher told Vox, after Trump’s first travel ban in 2017, that he was afraid that after working in America for more than three years at the Mayo Clinic, his application for permanent residency will be rejected and he’ll have to leave. Other researchers on visas and green cards from Iran said they fear leaving the US to visit family or go to conferences should they be barred from coming back home, and that this situation was untenable and had them thinking about alternative places to live.

As Vox’s Dara Lind reminds us, this isn’t the last we’ll be hearing about the travel ban. “In theory, the legal fight over the travel ban isn’t over, since the Supreme Court is still instructing the 9th Circuit to rule on the merits of the ban,” she writes. “But by decreeing that the legal challenges to the ban aren’t ‘likely to succeed’ on the merits, the court has just made it extremely difficult for the ban to get struck down in future.”

From the bench to the bedside, Trump’s approach isn’t just going to hurt the health system in the future — it’s already hurting it now.