Seroprevalence of Antibodies to SARS-CoV-2 in 10 Sites in the United States, March 23-May 12, 2020

Abstract

The first case of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in the US was reported in Washington State on January 20, 2020. The first US case linked to community transmission was reported in California on February 26, 2020, followed by subsequent cases resulting from community transmission reported in Washington on February 28 and New York on March 3.^1-5 Since January 2020, states have been recommended to report all laboratory-confirmed cases to the Centers for Disease Control and Prevention (CDC).⁶ Quiz Ref ID Reported cases, however, likely represent only a fraction of SARS-CoV-2 infections, as an unknown proportion of cases are mild or asymptomatic, or they are otherwise not diagnosed or ascertained through passive public health reporting.^7-9 Furthermore, viral testing has been limited in many sites and was often reserved for severely ill patients early in the US outbreak, and testing availability has changed rapidly. Each of these issues could confound estimates of incident cases and epidemic dynamics that use only case-based reporting data.