Washington (AP) — U.S. regulators are allowing emergency use of the first rapid coronavirus test that can be done entirely at home. The announcement by the Food and Drug Administration late Tuesday represents an important step in U.S. efforts to expand testing options for COVID-19. However, the test will require a prescription, likely limiting its initial use. The FDA granted emergency authorization to the 30-minute test kit from Lucira Health, a California manufacturer. Previously the FDA had only allowed the use of a handful of tests that allowed people to collect samples at home, which then had to be shipped to a lab.