Originally Posted by Skeptic Ginger
Some do many don't. The FDA has been coming down a some of the hundred plus purveyors of antibody tests that haven't even applied for an emergency authorization. Many of those are crap. Some tests deployed in Japan in a large group that hasn't had Covid-19 has a positive rate of under 0.1% so at least that test had decent specificity. Sensitivity, OTOH, is harder to quantify as there are fewer known positives to test against.