AbstractBackground. SARS-CoV-2, the virus that causes COVID-19 disease, was first identified in Wuhan, China in December 2019, with subsequent worldwide spread.

Blood samples collected in mid-December indicate possible infections more than a month before the known first case of Covid-19, but do not show community transmission.

The new coronavirus infected people in the U.S. in mid-December 2019, a few weeks before it was officially identified in China and about a month earlier than public health authorities found the first