When did COVID-19 first come into the United States? It's a question that is being asked once again.
"On January 21 is when we had the first confirmed patient with COVID in this country and even then the sense was, 'Did we really catch the very first patient'?" said Dr. Sanjay Gupta, CNN Chief Medical Correspondent.
A new study published in the journal Clinical Infectious Diseases suggests that was not the first US case. Scientists at the CDC analyzed almost 7,400 blood donations collected in the nine states by the American Red Cross from mid-December 2019 through mid-January 2020.
Of the samples tested, more than 100 were found to have novel coronavirus reactive antibodies, including ones collected from California, Oregon and Washington from December 13 through December 16, 2020. Those antibodies may appear from past infections with the virus that causes COVID-19, leading the study's authors to believe their may have been infections in the United States in mid-December of last year.
"This is a highly contagious virus that almost from the beginning started to transmit among humans in China it was spreading around the world," said Gupta. "An outbreak anywhere is an outbreak everywhere. I think that's what this reminds us of."
According to the CDC, antibodies usually start developing within one to three weeks after COVID-19 infection.