seroprevalence survey in 25 U.S. metropolitan areas to understand the percentage of people in the United States who may have been infected with SARS-CoV-2, the virus that causes COVID-19.This is the largest nationwide COVID-19 seroprevalence survey to date, and it will be conducted in collaboration with the National Institutes of Health, the Food and Drug Administration (FDA), Vitalant Research Institute (VRI), and large blood collection organizations, including Vitalant, American Red Cross, Bloodworks Northwest, New York Blood Center, OneBlood, The Blood Center, Versity, Blood Bank of Hawaii, Carter Blood Care, and Banco de Sangre de Servicios Mutuos.This seroprevalence survey will expand an ongoing National Institute of Allergy and.