If Coronavirus Is Contained in the U.S., Why Are Public Health Officials Worried?BookmarkFeb 27 2020, 2:46 AMFeb 27 2020, 9:38 AMFebruary 27 2020, 2:46 AMFebruary 27 2020, 9:38 AM(Bloomberg) -- Walling off travelers from mainland China to the U.S. is one thing. Walling off the world is far more difficult.Disclaimer