There’s an insurmountable backlog of virus tests. A rapid test could help.

As the U.S. deals with massive delays in COVID-19 testing, doctors and scientists say another type of diagnostic test could alleviate the stress on labs. Rapid, or point-of-care, tests deliver results in just minutes, while lab-based tools can take days.

“Every day they wait is another day they need to quarantine, or if they’re not, it’s another day they could be infecting other people,” Dr. Keith Jerome, who directs the molecular virology lab at the University of Washington medical school, said in an interview. “If you’re getting results within 20 minutes, you can start taking the appropriate actions right away.”

The National Institutes of Health announced Wednesday what it called an “unprecedented effort” to ramp up testing technology. Funded by $1.5 billion in federal stimulus money, the program will focus on creating rapid tests and distributing them more widely.

It’s also being called for by lawmakers and top federal health officials. President Donald Trump promised more rapid testing during his briefing Tuesday. And Dr. Brett Giroir, who is overseeing the nation’s COVID-19 testing, said this month that he expected 5 million additional “point-of-care” tests in July, with a goal of 20 million or more by September.

The tests produce such quick results because samples aren’t sent off to labs. Instead, they’re inserted directly into a machine housed at a doctor’s office or a hospital. The machine does the entire analysis, so instead of hours, it takes just minutes to get results — similar to rapid flu or strep tests used by most doctors.

Six point-of-care tests are authorized by the Food and Drug Administration, including two antigen tests, which look for certain proteins in the virus rather than genetic material.

As promising as the rapid tests seem to be, a significant problem prevents more doctors and clinicians from using them. Most aren’t as accurate as lab-based tests, and, in some cases, they can have shockingly high rates of false negatives.

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Joseph Petrosino, director of molecular virology and microbiology at Baylor College of Medicine, compares it to eating at a fast-food joint.

“If you go to a gourmet restaurant, you don’t expect your meal to be ready in five minutes,” he said. “But if you’re on the go and you eat fast food, the quality of food is usually a sacrifice, compared to the gourmet restaurant. That’s the same thing in the testing world.”

One of the more popular rapid tests, Abbott Labs’ ID NOW point-of-care test, which promises results in as little as five minutes and was once touted by the White House, came under fire in recent weeks after a small study found that it returned false negatives for nearly 50 percent of certain samples compared to a rival test. While other studies found more accurate results, it was enough for the FDA to issue an alert in May. The agency has received 147 adverse event reports about the test.

“The reality is that trying to do this really fast — the combination of fast and sensitive — turns out to be really a challenge,” said Dr. Christopher Polage, director of the clinical microbiology laboratory at Duke University Health System.

Polage said COVID-19 testing is a lengthy process. In the lab, scientists use special reagents that amplify or copy a sample’s genetic material to test for the virus. The process takes several hours. When you try to short-cut it for a rapid test, you can end up trading off the test’s sensitivity.

“No patient is ever going to wait at a clinic for eight hours,” Polage said. “So it’s really difficult and, in some cases, impossible to get an equivalent result in a fraction of the time.”

Jerome said, “You have to really keep in mind that there is a trade-off that you’ve made for that speed, and the trade-off is they’re not as sensitive, which means they’re going to miss some people who actually have COVID and tell them COVID isn’t there.”

A point-of-care test made by Cepheid Inc. of Sunnyvale, California, which gives results in about an hour, has been shown to be nearly as accurate as lab-based tests. But scientists say that the machine is expensive and that, as with some lab-based tests, some of the reagents it uses are in short supply.

“If you can wait an hour, you can get really good results,” Jerome said. “The issue with those has been just shortages of reagents, and the machine itself is just not available enough that everybody can have one.” He said UW Medicine, the health care system affiliated with the University of Washington, can use it only in the emergency room, where it needs to quickly test trauma patients so doctors and nurses know what kind of protective gear they need to wear.

But some doctors say that instead of focusing on rapid tests, which are notoriously difficult to perfect — both rapid strep and flu tests also have issues with accuracy — the U.S. should focus on fixing capacity issues with lab-based tests, which are being slowed in part because of supply shortages.

“We have the equipment, but we can’t get the reagents,” Jerome said. “We did a little over 7,000 tests yesterday in my laboratory. But we could have done 7,000 more if we had full allotments of reagents.”

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The delays in testing have a real impact for people like Frank Borsa, 55, who anxiously waited for days to find out whether he was infected after he returned to Brooklyn, New York, from Miami.

“It’s really frustrating,” Borsa said while he was still waiting for the results. “I’ve called repeatedly. What you get is ‘it’s taking a little bit longer.’ It’s very difficult, because you don’t know how to go forward.”

He finally got his results 12 days after he took the test at a New York City urgent care center. He was negative. But he said he now understands what the hubbub around testing is all about.

“Even though there might be hundreds of thousands of tests performed per day, if people are not getting their results, this is never going to end,” he said. “The communication is there’s tons of tests. But if there’s no results, what good is it?”