WASHINGTON—Detroit’s Big Three automakers and the United Auto Workers (UAW) union said on Tuesday that they will reinstate the wearing of masks at all U.S. plants, offices, and warehouses, regardless of vaccination status, beginning on Wednesday. General Motors Co, Ford Motor Co, and Stellantis NV said in a joint statement with the union the move is in response to the Center for Disease Control and Prevention’s (CDC) change in COVID-19 guidance for masks for fully vaccinated people related to the Delta variant. The CDC said last week that fully vaccinated people should wear masks indoors in public spaces in places with substantial or high COVID-19 community transmission rates. The CDC said on Monday that almost 80% of U.S. counties are now at those levels. At least one major international automaker also plans to reinstate mask requirements for employees later this week, a person briefed on the matter told Reuters. In June, …