In Delaware, presumptive Democratic presidential nominee Joe Biden on Thursday called for a nationwide mask mandate. Biden’s call came as Dr. Robert Redfield, the director of the Centers for Disease Control and Prevention, said U.S. residents must adopt public health measures or face the “worst fall” for public health in U.S. history.

Dr. Robert Redfield: “Wear a mask, social distance, wash your hands, and be smart about crowds. You do those four things, it will bring this outbreak down. But if we don’t do that, as I said last April, this could be the worst fall, from a public health perspective, we’ve ever had.”