https://www.wired.com/story/everything-we-know-about-covid-19-antibody-tests-so-far/

Antibody tests are big news right now. Many people consider these blood tests key to "reopening the economy" and easing back on social distancing, sending us back to work and to some semblance of a normal social life again. The problem is that, despite the rush to make them quickly available in huge numbers to people in all places, it’s not clear yet if most of the tests are any good, or what negative or positive test results even mean.

"We have very high hopes that a positive antibody will protect us against future infections," says Dr. Rekha Murthy, an infectious disease specialist at Cedars-Sinai Medical Center in Los Angeles, "but this pandemic has evolved so rapidly, we haven’t had the opportunity for the data and the science to back up our hope and our assumptions."