Two Washington state residents who were sick in December tested positive for coronavirus antibodies, indicating that the virus may have been spreading in the state well before its first confirmed COVID-19 case in January, according to The Seattle Times.
Though there are limitations to antibody tests and their accuracy with regard to identifying previous COVID-19 infections, the positive test results, combined with the clinical symptoms both residents were showing in December appear to meet the CDC's COVID-19 definition.
"They are being considered 'probable,'" a spokesperson for the Snohomish Health District said in an email May 14 to The Seattle Times.
The tests throw into question the first official case of COVID-19 in the country, which was reported Jan. 20 in Snohomish County, Washington.
There may not have been "one introduction or Patient Zero" for the virus, Art Reingold, MD, a public health epidemiologist at the University of California at Berkeley told The Seattle Times.
"There were likely earlier and multiple introductions of the virus," he said.
The official timeline for the virus' spread in the U.S. has been called into question previously. Autopsy results reported in late April from Santa Clara County, Calif., show two patients with COVID-19 died in their homes on Feb. 6 and Feb. 17. Previously, officials had reported the nation's first COVID-19 deaths occurred when two people died of the disease in Seattle Feb. 26.
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