Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, said at a Friday briefing that infectious new variants may be threatening to derail the country's recent progress.
Copyright 2021 NPR
Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, said at a Friday briefing that infectious new variants may be threatening to derail the country's recent progress.
Copyright 2021 NPR