Antibody Tests Yield Unreliable Results.
BALDWIN: A lot of people are pinning their hopes on antibody tests as a way to get back to work and get the economy back up and running. And these tests look at whether people have been infected with the virus and subsequently have antibodies. But there is a lot of uncertainty surrounding them at the moment. For one, it's not clear how long one's immunity lasts. As the White House task force's Dr. Deborah Birx acknowledged to CNN.</s>BIRX: WHO is being very cautious. I think what WHO is saying, we don't know how long that effective antibody lasts. And I think that is a question that we have to explore over the next few months, and over the next few years.</s>BALDWIN: "The New York Times" reports over the past few weeks, dozens of scientists have been evaluating whether 14 antibody tests now on the market are reliable, and the results are falling short. Scott Hensley is an associate professor of microbiology at the University of Pennsylvania. So, Scott, thank you so much for being on with me. And I just wanted to ask you, first, about the reliability of these antibody tests. And just total transparency, this is my first day back at work after recovering from coronavirus, and I'm currently trying to find an accurate FDA-approved antibody test. And I read this piece over the weekend in "The Times," where it talked about -- you were quoted, these 14 antibody tests, but only three had consistently reliable results, and then only one of the three didn't deliver a false positive. So my takeaway is that we're still very much in the wild west, are we not?</s>SCOTT HENSLEY, DEPARTMENT OF MICROBIOLOGY, UNIVERSITY OF PENNSYLVANIA: Well, Brooke, that's one way to put it. I'm glad to hear that you're feeling better. And yes, there are so many tests out in the market right now. And, you know, some of them are probably pretty good and others not so good. And these -- the antibody testing is just so important as we try to think about coming back together as a society. And it's unfortunate that the market's been flooded with some of these tests that are just not accurate.</s>BALDWIN: Help me understand. Use me as an example, right? I had COVID, I just, a couple days ago, tested negative for it, cleared me so I could come back in and do what I'm doing right now. If I took an antibody test and it came back positive, does that mean I'm immune?</s>HENSLEY: OK. So, yes, let's take you as an example. So I think you're up in New York, right?</s>BALDWIN: Yes.</s>HENSLEY: So let's say we bleed (ph) 100 people in New York, we take the blood from those hundred individuals and run a test. If there's a five percent false positive with that test, that means five of those 100 people that we just tested are going to come up positive, but they weren't really exposed. Well, say that seroprevalence in New York right now is a true five percent, that would mean --