A new National Institutes of Health (NIH) analysis of more than 24,000 stored blood samples reveals SARS-CoV-2 antibodies in nine participants in five states as early as Jan 7, 2020, indicating that COVID-19 was in the country weeks before the Centers for Disease Control and Prevention (CDC) announced the first US case on Jan 21.Because immunoglobulin G (IgG) antibodies aren't detected until about 2 weeks after infection, the findings date the exposures to late December, although whether the participants were infected in the United States or abroad is unknown."Antibody testing of blood samples helps us better understand the spread of SARS-CoV-2 in the U.S.