Mask mandates make a return — along with controversy Dan Diamond A transit passenger wears a mask while awaiting a light rail train in Los Angeles, which has reimposed mask mandates for people — vaccinated or not — inside public establishments. (Patrick T. Fallon/AFP/Getty Images) Two months after the Centers for Disease Control and Prevention said vaccinated individuals didn’t need to wear masks in most settings, a growing number of experts are warning it’s time to put them back on. First, there was Los Angeles County, where the rising menace posed by the delta variant of the coronavirus prompted health officials to reimpose a mask mandate. Then, Bay Area health officers on Friday recommended that residents of seven counties and the city of Berkeley, Calif., resume wearing masks indoors. Mask mandates are being discussed, too, in coronavirus hot spots such as Arkansas and Missouri, where cases have sharply increased in recent weeks and many residents remain unvaccinated.