The US Centers for Disease Control and Prevention on Thursday abruptly changed its guidance on masks and social distancing, saying people who are fully vaccinated against Covid-19 don’t have to wear masks indoors, and they don’t have to keep their distance from others.The US Centers for Disease Control and Prevention on Thursday abruptly changed its guidance on masks and social distancing, saying people who are fully vaccinated against Covid-19 don’t have to wear masks indoors, and they don’t have to keep their distance from others.