Can antibody tests tell if you're immune to COVID-19?

As the new coronavirus burns its way across the world, scientists are rushing to find ways to identify those who have been infected -- including those who have recovered from COVID-19. Those people, the thinking goes, may be immune to the deadly virus and could theoretically help restart the economy without fear of reinfection. One key piece of this puzzle is rolling out what are known as serological tests that look for specific antibodies in a person's blood. So far, they have been used to estimate how much of the population has been exposed in different areas, such as New York City and Los Angeles. But what are these tests, and can they really help to identify who is immune to SARS-CoV-2? From how they work to what they tell us, here's everything you need to know about coronavirus antibody testing.