The SARS-CoV-2 virus has now had ample time to mutate, as reports of the proliferation of multiple variants make clear, and the U.S. FDA’s Tim Stenzel said the agency is now focused on three variants, including one recently reported from Israel. Stenzel said on the latest COVID-19 testing town hall that one of the key concerns regarding existing authorized tests is the potential for loss of sensitivity, a problem the agency hopes to overcome without the use of live virus.