New Test Begins To Help Scientists Respond To Coronavirus

Scientists are missing a proven tool to help them fight the coronavirus: A blood test that can tell who has been exposed in the past. U.S. scientists are developing one — China may already have one.

DAVID GREENE, HOST:

We're covering the election as well as another big story - the coronavirus. As it spreads more widely around the globe, scientists are starting to use this powerful new tool. Researchers in Asia are using a blood test that identifies people who've previously been exposed to the virus. As NPR's Richard Harris reports, this is helping them figure out how to respond to COVID-19, the disease caused by coronavirus.

RICHARD HARRIS, BYLINE: The current lab test for the coronavirus used in the United States identifies people who are currently spreading the virus. And that's crucial information, but that test doesn't reveal who had previously been infected. That's important, too, for understanding the unfolding epidemic. Lauren Ancel Meyers at the University of Texas at Austin says these tests look for antibodies, which the body produces a week or two after someone has been infected.

LAUREN ANCEL MEYERS: They can identify people who have been infected but never identified as infected, either because they never developed symptoms or they had symptoms that were never correctly diagnosed.

HARRIS: That means the test can identify silent infections in addition to people who have recovered. If it turns out a ton of people got infected but didn't get sick, that means the virus is less fatal than it now appears. And Meyers says that's just one insight the test will bring.

MEYERS: One of the key questions that we're grappling with is, what's happening with children in this outbreak?

HARRIS: Very few have ended up in the hospital. Is that because they're not getting infected or they're getting infected but not getting sick? An answer to that question will help public health officials figure out whether it makes sense to close schools if there's a big outbreak.

MEYERS: Without knowing whether children are getting infected or the rate at which they're getting infected or how severe the disease is in children, it's really hard for us to project what the impacts of school closures might be.

HARRIS: The Centers for Disease Control and Prevention is currently developing an antibody test, but they're now playing catch-up with scientists in both Singapore and China. Dr. Stanley Perlman is a coronavirus researcher at the University of Iowa.

STANLEY PERLMAN: I think that the Chinese laboratories have been amazingly fast. I think they already have some tests that they're using. I haven't seen any publications to show that they're validated - and of course, that's what you want to know. But I think they're really capable of doing this pretty quickly.

HARRIS: Validating the test is critical. Otherwise, you have no idea how many false findings you're getting. You don't want to flag people who have been infected with one of the harmless coronaviruses that are already in wide circulation. Assuming the Chinese test is reliable, scientists there can figure out if these antibodies provide good protection against the disease and how long they persist. People who have been exposed to the virus might only be immune for a matter of months, Perlman says.

PERLMAN: So you could imagine - if the virus is around in a year and the antibodies wane, that maybe someone could be reinfected. Again, this is speculative. We don't know.

HARRIS: That could mean repeated waves of the disease rather than doing most of its damage in one particularly bad year. Because it takes the body some time to produce these antibodies, this test is not useful for tracking the illness in real time, so it won't replace the diagnostic test the CDC is currently running. But to understand where the epidemic is going, we need to know where it's been, says Andrew Pekosz at Johns Hopkins University.

ANDREW PEKOSZ: Has this virus ever entered the population undetected and been spreading? Again, if it's a mild disease that's induced by this, it may not have registered a large enough number of cases to get on the public health radar screen.

HARRIS: That was the case for Ebola and HIV. Those viruses circulated in humans for many years before scientists recognized the diseases they cause. Scientists discovered this by running an antibody test on blood that had been stored long ago. Pekosz says via Skype that this test can answer so many questions, demand for it will be fierce.

PEKOSZ: So you have to also think about scale of production and making sure that the test that you're doing can be scaled up for widespread use.

HARRIS: Since the federal government has declared a health emergency, approval will speed through the Food and Drug Administration. But first, they need a product they can evaluate.

Richard Harris, NPR News.

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