Transcript for Potential scientific breakthrough regarding COVID-19
There's also encouraging news about antibodies and immunities. Researchers finding that antibodies do provide some immunity. And with so many tests out here in the U.S., how do we know which ones are most accurate? Here's Eva pilgrim. Reporter: Tonight, a potential scientific breakthrough. A study of hospitalized patients finding nearly all with the virus had some sort of immunity. Emory university researchers finding a specific virus-neutralizing antibody in patients within six days of testing positive for covid-19. Not only shows that you've been exposed to the virus and have made antibodies against it, but those antibodies at least, you know, to the extent we've tested now, seem to correlate with blocking a viral infection. Reporter: By finding that key antibody, scientists say it will help them create a better test and vaccine. One unknown, how long does protection last? I think going forward, it will be important to understand the durability of these immune responses over the next few months to years after infection. Reporter: But tonight, questions about the reliability of some of the crucial antibody tests on the market. At its peak, there were 170 different ones, most without fda emergency use authorization. This rapid antibody test bought at a pharmacy uses just a drop of blood and works similar to a pregnancy test. The screen with results turning red. It didn't work. There's apparently no line at the front door. I first took a test on may 1st and it came back negative for antibodies. The results came with this notification. "This test has not been reviewed by the fda. Negative results do not rule out a covid infection. Positive results could also be due to past or present infection with non-covid coronavirus strains." Today I'm taking another test. One of the 12 on the fda's emergency use authorized list. Following the fda guidelines and the CDC guidelines, we're looking at every test and make sure that it's validated and has emergency use authorization. Reporter: The full list of those authorized tests is on the fda's website. David? Eva, thank you. We're going to turn to the
This transcript has been automatically generated and may not be 100% accurate.