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Why Covid-19 test results are taking so long

A person gets a Covid-19 test from their car. A health care worker in PPE is talking to them while their gesture.
AP Photo/Matthias Schrader
You’ll hear anywhere between four and 14 days.
Published Last updated This article is more than 2 years old.

At the beginning of the pandemic in the United States in March, shortages of coronavirus tests caused massive delays in accurate case counts. Now, there are still diagnostic delays, with the wait times for results reaching up to two weeks, but for a completely different reason: There are too many kinds of tests.

How did the country get here? First, in February, a faulty reagent fiasco rendered tests from the US Centers for Disease Control and Prevention—at the time, the only ones authorized—useless. So the head of the department of Health and Human Services determined that the novel coronavirus was enough of a threat to justify the emergency use of certain tools. Instead of its typical rigorous review, the US Food and Drug Administration would give tests and treatments a different kind of temporary clearance to get them on the ground as soon as possible.

It worked—sort of. The US FDA has now granted emergency use authorization (EUA) to about 150 tests that can detect genetic material from SARS-CoV-2.

Broadly, these tests all use a method called a polymerase chain reaction, or PCR. That technique requires sterile swabs, fluids to separate genetic material from the swabs, and equipment and reagents to multiply that material. At first, shortages of these different components, as well as shortages of personal protective gear for the health care workers performing the tests, were causing delays in testing and results.

Now, the problem is slightly different: There are still looming threats of protective equipment and general lab equipment shortages. But the bigger problem is that because there are so many tests in use, labs are struggling to confront shortages for the more specialized ones.

Four of these diagnostic tests are created by two massive companies in the US: Quest Diagnostics and LabCorp. These two companies usually serve pop-up testing clinics run by either local health departments or private health groups. Quest can handle 135,000 diagnostic tests per day, and a spokesperson from LabCorp told Quartz that their facilities can handle 180,000 tests per day.

Both give priority testing to certain groups, who can expect to get tests back in a day. That includes people who work in health care and have symptoms, people who are in the hospital or need to go to the hospital, or people who live in close quarters with other vulnerable adults, like nursing homes. Others can get their results back in a few days, though actual results may vary.

Hospital labs, though, have purchased more of the EUA tests from smaller companies. And this is where having too many options has been a problem.

“The challenge on the clinical lab side is we can’t get what we need,” says Robin Patel, a microbiologist who runs the infectious diseases research laboratory at the Mayo Clinic in Rochester, Minnesota. Each of these new SARS-CoV-2 detection tests work similarly, but there are slight differences in the equipment they require. The second there’s a shortage in one piece of equipment required for one test—like a specific plastic tube—then the whole testing platform comes to a halt.

Normally, lab directors try to avoid equipment with specialized parts. It’s more efficient to set up complementary lab equipment where technicians can swap out interchangeable parts as necessary.

But some of the EUA Covid-19 tests are highly individualized. Patel calls them “black boxes.” A technician puts a sample into a machine, and then, without having to worry about pipetting or moving samples around at all, it can spit out a result. The pro is that these tests are fast. The con, though, is that if the machine breaks, there’s no substitute. The machine is out of commission until they can get a repair. During that time, there’s increased strain on other machines in the lab.

Labs themselves are performing incredible feats to keep their own systems up and running. Some have personnel working in shifts to cover 24 hours a day. Others are decreasing testing capacity for other infectious diseases like Lyme disease or anaplasmosis so they can have more capacity for Covid-19. Others are even sending samples to neighboring hospitals or even partners with LabCorp or Quest. All of that time, however, adds to the time it takes for a person to get their results back.

Emergency approval of so many tests was necessary to support wide-spread testing. But in practice, it introduced even more ways for a fragile system to fail.

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