This past Thursday, Donald Trump visited the National Response Coordination Center for a teleconference with the nation’s governors about how to handle the COVID-19 pandemic. The center, which is situated inside the headquarters of the Federal Emergency Management Administration, in Washington, is designed, in the agency’s words, to coördinate “the overall Federal support for major incidents and emergencies.” Trump—along with Mike Pence, and several other Cabinet and sub-Cabinet officials—sat around a table in a gray-walled conference room, while the governors were patched in from around the country. The governors said their states needed personal protective equipment (P.P.E.) for health-care workers, ventilators for patients, block grants for their balance sheets, and the National Guard to build hospitals and distribute food. They also needed tests. Kristi Noem, of South Dakota, said that her state’s public-health laboratory—the only lab doing COVID-19 testing in the state—had so much trouble securing reagents that it was forced to temporarily stop testing altogether. “We, for two weeks, were requesting reagents for our public-health lab from C.D.C., who pushed us to private suppliers, who kept cancelling orders on us,” she said. In order to get her public-health lab the reagents it needed, Noem said, “we had to get a little pushy with a few people.”

Trump and his team sought to reassure the governors. Admiral Brett Giroir, an assistant secretary at the Department of Health and Human Services, who was appointed two weeks ago to coördinate the federal effort to get testing back on track, said, “We’re very effectively transitioning to large-scale testing by leveraging all components of our American health-care system, including C.D.C. and the state public-health labs, health care and hospitals, and large commercial labs.” Giroir told the governors that, in the twelve days between March 2nd and March 14th, more than ten million tests had been made available in the U.S. And, citing numbers from the F.D.A., he suggested that another seventeen million would be added by March 28th. “We have plenty of tests on the back side. We have plenty of supplies on the front side,” Giroir said. Pence, too, emphasized that “now tens of thousands of more tests are being performed literally every day,” while Trump, responding to Noem’s difficulties securing reagents, told her not to be concerned. “We got you, Kristi,” he said. “There is tremendous supply.”

The next day, the Association of State and Territorial Health Officials, the Association of Public Health Laboratories, and the Council of State and Territorial Epidemiologists—which, together, represent virtually the whole of the country’s state-level public-health infrastructure—issued a joint statement warning about “widescale shortages of laboratory supplies and reagents” for COVID-19 testing. Because of these shortages, the statement said, testing ought to be reserved for three groups of suspected cases: health-care workers and first responders; the elderly, especially those who live in nursing homes and other group settings; and people for whom a confirmed COVID-19 diagnosis had the potential to meaningfully change their treatment plan, such as those with underlying health conditions.

An alert sent out earlier in the day by New York City’s Department of Health and Mental Hygiene was even more dire. Mildly or moderately ill people seeking COVID-19 tests, the D.O.H.M.H. warned, posed a serious infection risk for hospitals and clinics, and were creating a run on the city’s extremely limited P.P.E. stocks and testing supplies. For that reason, the department was “directing healthcare facilities to IMMEDIATELY STOP TESTING NON-HOSPITALIZED PATIENTS FOR COVID-19 unless test results will impact the clinical management of the patient.” Even health-care workers and first responders who had been exposed to infected patients but did not have symptoms would no longer be tested. As the alert went on to warn, again in bold capital letters: “COVID-19 testing is only indicated for HOSPITALIZED PATIENTS.”

In late February, nearly three weeks after the first batch of C.D.C. test kits that was shipped to state and local labs proved faulty, the Trump Administration pushed through a series of regulatory moves to expand the nation’s test capacity. On February 29th, the F.D.A. allowed so-called high-complexity labs to develop and run their own tests. Starting on March 12th, the F.D.A. issued a series of Emergency Use Authorizations to commercial test companies, which allowed those companies to manufacture and distribute tests without going through the agency’s normally onerous approval process. And, last Monday, the F.D.A. announced a new policy that allows state and territorial public-health laboratories to authorize tests at other labs without the need for additional federal approval. In effect, the policy pushed regulatory authority for COVID-19 testing out of the federal government and down to the states and territories.

The F.D.A.’s changes succeeded in clearing away many of the regulatory obstacles to new testing. And yet they did little to solve what now appears to be the major bottleneck in deploying widespread testing across the United States. No longer do we need to worry about a single authorized test protocol, or a limited number of laboratories that are allowed to carry out that test. The current trouble is a critical shortage of the physical components needed to carry out tests of any variety. Among these components are so-called viral transport media, which are used to stabilize a specimen as it travels from patient to lab; extraction kits, which isolate viral RNA from specimens once they reach the lab; and the reagents that do the actual work of determining whether the coronavirus that causes COVID19 is present in the sample. Perhaps the most prosaic shortage, but also the most crucial, is a lack of test swabs, which look like glorified Q-tips. Specially designed to preserve viral specimens, they’re what a doctor sticks up your nose or down your throat to collect the necessary biological material.

The swab shortage is happening for the same reason that all the other test components are limited—namely, a global pandemic has created a global demand for them—but it is subject to a further complication. Copan, one of the major manufacturers of the sort of swabs needed for COVID-19 tests, has its headquarters and manufacturing facilities in Lombardy, Italy, which has been hit particularly hard by the disease. A spokesperson for the company says that the national lockdown in Italy has not affected production at its factories, but last week the U.S. Air National Guard had to use one of its C-17 cargo planes to bring an order of eight hundred thousand swabs back to the U.S. According to Defense One, the plane flew on Monday from the Aviano Air Base, in Italy, not far from the headquarters of Copan, to Memphis, where a FedEx distribution center is situated; the Times later reported that the airlift had been arranged by Peter Navarro, a Presidential trade adviser, and that the Administration hoped similar efforts would bring 1.5 million swabs into the country every week. On Saturday, a company spokesperson told me that Copan did not make “special deals” with governments but was “shipping to the U.S.A. the maximum amount that we are capable of, on a best effort basis” through its usual distributors.

The shortage of testing components is having its most drastic effects in the parts of the country that are seeing the highest prevalence of COVID-19. According to Deborah Birx, the response coördinator for the White House Coronavirus Task Force, more than fifty per cent of confirmed cases of the disease have been found in just ten counties, in three states—Washington, New York, and California. In New York City, as of Monday, some fifteen thousand cases have been confirmed, about a third of the country’s total. (Given the testing deficit, the actual prevalence may be several times that.) According to Jennifer Rakeman, the director of the city’s public-health laboratory, “There’s widespread community transmission in New York City.” What that means for residents of the city, she said, is that “if you have symptoms of influenza—like a cough, shortness of breath, fever, sore throat—the pre-test probability that you have COVID-19 is very, very high.”