FDA authorizes new test, built with machine learning, to detect past Covid-19 infections

The Food and Drug Administration on Friday issued an emergency authorization for a new test to detect Covid-19 infections — one that stands apart from the hundreds already authorized. Unlike tests that detect bits of SARS-CoV-2 or antibodies to it, the new test, called T-Detect COVID, looks for signals of past infections in the body’s adaptive immune system — in particular, the T cells that help the body remember what its viral enemies look like. Developed by Seattle-based Adaptive Biotechnologies, it is the first test of its kind. Adaptive’s approach involves mapping antigens to their matching receptors on the surface of T cells. They and other researchers had already shown that the cast of T cells floating around in an individual’s blood reflects the diseases they’ve encountered, in many cases years later. The next step is trying to unlock that information to help diagnose those past infections.