Evolution and mutation of SARS-CoV-2 virus has made COVID-19 diagnosis a moving target. On Feb. 22, 2021, the U.S. Food and Drug Administration issued new guidance telling developers of SARS-CoV-2 tests how to evaluate the impact of viral mutations on test performance. The guidance covers all three types of SARS-CoV-2 tests—molecular, serology and antigen—including both tests seeking and that have already received Emergency Use Authorization (EUA). The Diagnostic Challenge Like other living organisms, viruses evolve over time. And they evolve quickly. Virus evolution often outpaces diagnostics development. As a result, diagnostics designed to detect current iterations may be incapable of detecting the mutated virus by the time they are put into use. This creates the risk that the test will produce false negative results. The concern is that SARS-CoV-2 virus evolution may be following this pattern. Since the original virus was first detected over a year ago, variants of it have turned up across the globe and in the U.S., including the B117 variant first isolated in the U.K., the B1351 South African variant and the P1 Brazilian variant. To keep up with the pace of evolution, developers of SARS-CoV-2 tests must evaluate how viral mutations may affect test performance. […]