ON MARCH 17, GOV. J.B. PRITZKER OF ILLINOIS announced his state’s first coronavirus-related death. He took the occasion to decry the ongoing shortage of tests. “I’ve requested and now I’m demanding the White House, FDA and CDC produce a rapid increase in test supplies nationwide—or get out of the way; allow us to get them elsewhere ourselves,” he said.

COVID-19 tests are in critically short supply, a point made often at national briefings over the past weeks. The need for tests is especially keen for clinicians who must be able to quickly diagnose and quarantine those with the virus. If COVID-19 cases are not isolated, the infection can ravage other vulnerable patients. One solution: Hospitals have begun to cook up their own version of the test, a contested practice with a long history.

Hospitals send many of their day-to-day tests to large commercial laboratories. They can also run tests on-site for a much quicker turnaround. Often, they use manufactured kits that have been sold commercially and run through a regulatory approval process, but they also use tests that they themselves have created, sometimes from scratch. These latter are known as lab-developed tests (LDTs).

Devising an LDT for COVID-19 was a puzzle, but the stakes were high and hospital lab teams had good guidance on the steps and materials. “The global community has been transparent about how they developed their tests, so we had a ready framework for developing our own,” says infectious disease specialist Sarah Turbett, assistant director of the microbiology laboratory at Massachusetts General Hospital.

Because LDTs haven’t been approved through regulatory channels, they are often used just to give clinicians a rough idea of what they’re looking at or to test quickly for an infection. Some LDTs screen for rare diseases for which there are no commercial tests. The FDA “historically used an exercise of enforcement discretion to take a more laissez-faire approach” to the regulation of LDTs when they were developed and used in the same institution, says William McConagha, a former FDA attorney and now a partner at Skadden Arps, where he advises medical companies regulated by the FDA. The FDA did not require the LDTs to be approved or cleared by the agency.

That began to change in 2010, however. The FDA signaled it wanted most LDTs to go through its approval process—a move that sparked a fierce response. “The clinical labs argued that LDTs were a clinical service, not a product, and that FDA oversight would be an intrusion on the practice of medicine and inhibit innovation,” McConagha says.

The FDA and its supporters contended that if LDTs underwent the same review process as the products of commercial manufacturers, it would ensure the tests’ accuracy and safeguard public health. In 2017 the FDA asked Congress to settle the debate. The latest pending legislation would subject highly complex LDTs to the same set of FDA regulations as commercial diagnostic tests.

Then the COVID-19 crisis arrived. Hospital-developed COVID-19 tests promised to play a nimble and useful role, bridging gaps in the supply of approved test kits. They could deliver results in hours, not days. But it wasn’t immediately clear whether the federal government would approve of them.

On February 29, the FDA gave an answer, which offered something for both sides. It said that smaller labs capable of performing high complexity testing and large, multinational medical device manufacturers developing tests for commercial distribution would both need to follow an expedited process for these tests, involving the Emergency Use Authorization pathway. Under the February guidance, which was updated on March 16, the FDA further liberalized its normal review process under the EUA pathway to say that new COVID-19 tests could be used immediately on patients or distributed to clinical laboratories or health care workers. Within 15 working days, however, developers would have to submit data on the tests’ performance.

As part of this expedited approval process, the FDA waived the need for data showing how the tests worked in people. “The epidemic was only just emerging in the U.S., so we didn’t have the clinical cases to determine whether what we were developing actually worked,” Turbett says. “The FDA said we could validate our test using inactivated virus or genomic RNA in the absence of actual patient specimens,” she says.

Adds McConagha: “We see the FDA trying to establish some middle ground that balances its interest in overseeing the accuracy and the validity of these tests with the need to get the tests developed. These are complicated issues, and hindsight is 20/20. The government made a determined effort with the CDC test, but some have suggested that the FDA should have issued this guidance sooner.”

And even with relaxed requirements, some hospital lab directors have still expressed frustration. If testing hadn’t been delayed by the FDA’s procedures for expedited authorization, “I could have tested over 1,000 patients by now,” said Melissa Miller, director of the clinical microbiology laboratory at UNC Medical Center in Chapel Hill, North Carolina in a news report on March 11. “The necessary validations for the emergency authorization are time- and cost-prohibitive. We are way behind.”

On March 13, MGH began administering its own COVID-19 test to patients. Other hospital labs, such as those at Mayo Clinic, UNC School of Medicine and University of Washington School of Medicine, have also announced they are performing their own COVID-19 tests.

Commercial labs are also taking advantage of the new FDA protocol, and the diagnostics company Cepheid announced on March 21 that it had created a point-of-care COVID-19 test. It now also has EUA approval. The company says the test can detect the presence or absence of the virus within 45 minutes, and that it could be run on any of 5,000 testing machines owned by Cepheid in the United States.

The lab at UW Medicine in Seattle, among other medical center facilities, is now running up to 1,000 COVID-19 tests a day, according to Turbett. MGH’s lab is performing far fewer but expects to expand its capacity soon.

When MGH sent patient samples to the Massachusetts public health lab, it took as long as 72 hours to get results. Now, with its own COVID-19 test, the hospital’s lab can deliver results in 8 to 24 hours. “Faster diagnosis allows us to better triage and protect patients,” Turbett says. “It allows us to ensure the right precautions, like isolation and quarantine, are in place. Confirming the diagnosis with a test also opens the window to enrollment in some of the many therapeutic trials for patients with COVID-19 going on at the hospital.”

Although the way has been smoothed for more LDTs and commercial tests, hospitals and commercial manufacturers are now scrambling to find the reagents and platforms to run the tests—materials in short supply as global demand skyrockets. “We have to be more resourceful,” Turbett says. “We’ll explore whether other reagents or test components can give us the same results. We have to be nimble to respond to this.”