Antigen Tests For The Coronavirus Might Be Easier, But How Reliable? : Shots - Health News An antigen test could be quick, and much simpler and cheaper than the PCR tests now used to spot people infected with the novel coronavirus. But some scientists worry about an antigen test's accuracy.

A Next-Generation Coronavirus Test Raises Hopes And Concerns

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STEVE INSKEEP, HOST:

What's a way out of the shortage of coronavirus testing? A shortfall of tests has hampered the U.S. response from the start. There is still a shortfall, according to many experts, even though millions of tests have now been conducted. Now some Trump administration officials have been saying a different kind of test could help. NPR health correspondent Rob Stein has been checking the possibilities and the risks of antigen tests, and he's on the line. Rob, good morning.

ROB STEIN, BYLINE: Morning, Steve.

INSKEEP: What has made conventional testing so hard?

STEIN: Well, you know, Steve, they're very sophisticated tests. They're molecular tests that identify people by looking for genetic material from the virus that can be found by doing, you know, those swabs inside the nose.

INSKEEP: And so they're good, they're useful but they're complicated. They may require processing in a lab. What about this new kind of test?

STEIN: It's called an antigen test because instead of looking for genetic material from the virus, it looks for pieces of the virus - proteins called antigens. They stick out like spikes from the surface of the virus and can be found on cells of people who are infected. You know, antigen tests have been used for a long time to do all sorts of things like test people for the flu and strep throat and, you know, to do home pregnancy tests.

INSKEEP: Oh, which people do by themselves on themselves - so does that mean that an antigen test would just be simpler?

STEIN: Yeah, that's right. The big thing about antigen tests that could be a game changer is that they're fast and cheap and easy to make and use - a lot cheaper and less complicated than those fancy genetic tests. So it would be a lot easier to make and use millions of them to screen millions of people every day. That's crucial, you know, to reopen the country safely, you know, to do things like - say, you know, a company wants to test workers every day to see who's infected and so needs to stay home and who's in the clear and can safely come back to work and spot people who just got infected to keep them from spreading it and sparking new outbreaks.

Here's Dr. Deborah Birx from the White House Coronavirus Task Force talking about this last weekend on NBC's "Meet The Press."

(SOUNDBITE OF TV SHOW, "MEET THE PRESS")

DEBORAH BIRX: We have to have a breakthrough innovation in testing. We have to be able to detect antigen rather than constantly trying to detect the actual live virus or the viral particles itself and to really move into antigen testing.

INSKEEP: She didn't say we have a breakthrough in innovation. She said we have to have a breakthrough. So how close is the breakthrough?

STEIN: Yeah, that's right. You know, but I've been in touch with several companies that say they're already developing antigen tests designed to spot the virus really quickly and easily in saliva, just from a sample of their spit.

Lee Gehrke is a scientist at MIT and Harvard who's involved with one of these companies.

LEE GEHRKE: Looks very much like a pregnancy test, and they're very simple. They don't require special chemicals or training to use them, and they can give you a readout within about 15 minutes or so. And so it could be a very good way of solving the testing problem that we're having in the U.S. right now.

INSKEEP: Let me focus in on a word there - solving. Would this solve the problem?

STEIN: Well, you know, a reliable antigen test for the coronavirus could be a game changer, but some of the experts I've been talking to are skeptical. That's because when antigen tests have been used to do things like test for the flu and strep, they tend to miss a lot more infected people than the genetic tests, you know, maybe 15 or 20 out of every hundred infected people. So they worry about relying on an antigen test to keep the virus from spreading. Here's Jesse Papenburg from McGill University.

JESSE PAPENBURG: If you're using this test to screen people to make sure that they're not infected and then they can, you know, go back to work and things like that, then, you know, you giving people the message that they're not infected when actually they are and therefore transmitting.

INSKEEP: What are the test makers saying?

STEIN: Well, they say they're doing the studies that are needed to prove the test would be reliable and could match those fancy genetic tests. Or maybe the tests would have to be used to screen people and then get confirmed by other tests. And the Food and Drug Administration, which has been criticized, is developing standards for evaluating these tests.

INSKEEP: Rob, thanks so much.

STEIN: You bet, Steve.

INSKEEP: NPR's Rob Stein.

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