Missouri never had a statewide mask mandate, unlike many states, but as the COVID-19 pandemic spread rapidly last fall, many Missouri cities and counties rushed to adopt some form of face covering requirement. By November, more than half the state's population was required to wear a mask while in shared public spaces. But more recently, novel coronavirus caseloads have fallen sharply. Missouri has more than 6.1 million people; as of mid-May, 1.9 million were fully vaccinated against COVID-19, according to the News-Leader's data tracker. "Herd immunity" may prove impossible because significant minorities of Americans don't want to be vaccinated, but on May 13, the Centers for Disease Control announced that fully vaccinated Americans need not wear masks in most indoor public settings.