Public Health Response to the Initiation and Spread of Pandemic COVID-19 in the United States, February 24–April 21, 2020

From January 21 through February 23, 2020, a total of 14 cases of coronavirus disease 2019 (COVID-19) were diagnosed in six U.S. states, including 12 cases in travelers arriving from China and two in household contacts of persons with confirmed infections. An additional 39 cases were identified in persons repatriated from affected areas outside the United States (1). Starting in late February, reports of cases with no recent travel to affected...