The CDC’s recommendations now also align more closely with local health departments that already have reimposed mask mandates because of rising coronavirus cases, said Dr. William Schaffner, a professor and infectious disease expert at the Vanderbilt University School of Medicine in Nashville, Tennessee. “This gives more of an opportunity for local health departments to not look as though they’re doing something different than what the CDC is suggesting,” he said. “There was always an option for locals to make that determination, but now it’s much more explicit.” The CDC’s a...