Serologic Testing of US Blood Donations to Identify Severe Acute Respiratory Syndrome Coronavirus 2 and Other Coronaviruses, December 2019 to July 2020.

The samples tested in this study were broadly representative of the United States, and all were from individuals who had successfully donated blood. The antibody-reactive results of this study suggest that SARS-CoV-2 was likely present in the United States before 19 January 2020.