WASHINGTON—The District of Columbia will lift its indoor mask requirement starting next week, as local COVID-19 infection cases continue to trend downward. Starting Monday, Nov. 22, masks will no longer be required in many indoor spaces. A statement from the city Health Department announced that masks will still be required in certain settings, including schools, libraries, public transportation, ride-share vehicles and group-living facilities like nursing homes, dorms and jails. Also, private businesses will still be able to require customers to wear masks. The nation’s capital originally lifted its indoor mask requirement for fully vaccinated individuals in May, but reinstated it in late July as cases began to rise again. According to Health Department statistics, the current seven-day average of new cases—the department’s preferred metric—is higher than it was in May when the first mask requirement was lifted, but still well below the late-summer delta-variant peak in August and September. Mayor …