New York City has already been restricting who gets tested for COVID-19 in an effort to conserve medical resources, but now even patients being hospitalized for the virus might not be able to get tested to confirm that they have it.

The city is facing a “serious shortage” of the swabs used to take samples from patients suspected of having COVID-19, according to an alert the city Department of Health and Mental Hygiene sent to health care providers Saturday. “As the swab supply continues to decline, there is a real possibility hospitals will completely run out,” the alert warned.

Stephanie Buhle, a spokesperson for the city Health Department, said the timeline for swabs to run out “would likely be days, not weeks.”

Asked at his Sunday press briefing whether the city has been in touch about the shortage, Governor Andrew Cuomo said, “I haven’t heard that.” He didn’t respond to a question about whether the state has its own reserve of swabs.

News of the swab shortage comes shortly after Cuomo and Mayor Bill de Blasio said the only way to eventually get people back to school and work is to conduct widespread testing. That includes both blood tests to determine who has already had the virus and developed antibodies to fight it, and diagnostic tests to determine who is currently infected. While some patients can get a diagnostic test by coughing up mucus, most need to be swabbed.

The city is reaching out to medical supply manufacturers and labs in an effort to replenish the supply of swabs, but options are currently limited. “It's a supply chain issue--more demand than there is supply in the market,” Buhle explained. “It's not just limited to NYC or to city-run testing sites.”

A chart showing a steep drop-off in the number of COVID-19 tests administered.

The city’s Public Health Laboratory received 240 nasopharyngeal swabs and 240 collection tubes from the Missouri State Public Health Laboratory Saturday. “These will be sent out to the NYC hospitals most in need,” Buhle said. “However, they will not last long.”

Buhle said as the city seeks to build up testing capacity, priority will be for health care workers, first responders, patients who are hospitalized, and patients from “impacted communities, especially those over the age of 65 with preconditions and symptoms.”

At a press conference on Sunday, de Blasio announced targeted, community-level testing would be rolled out at five new sites, with one in each borough. But to carry out the “phase 2” testing expansion, de Blasio is asking the Trump administration for 110,000 individualized testing kits.

"We need to get these test kits in this week," the mayor said.