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Maybe Not the Source

The first reported coronavirus cases in Europe and the US might not be related to the subsequent outbreaks in those areas, the New York Times reports.

The first confirmed coronavirus patient in Washington — dubbed WA1 — was diagnosed in mid-January, with a second case following weeks later in late February. Previous research suggested that the virus infecting the second known case was a direct descendent of the one isolated from WA1, indicating the virus was quietly circulating in the area.

But, researchers led by KU Leuven's Philippe Lemey have come to a different conclusion. In their viral genome analysis posted to BioRxiv, they suggest a second, later introduction of SARS-CoV-2 to the area instead led to the second case and that the outbreak there started later than thought. This, they note, suggests there might have been a "missed opportunity when intensive testing and contact tracing" could have halted viral spread. A similar scenario played out in Europe, they further report in their pre-print. 

The University of Washington's Trevor Bedford, who did the previous analysis, writes on Twitter that the new analysis suggests he may have "wrong in the original assessment of a WA1 introduction, but correct in asserting significant community spread in Washington State on Feb 29." He adds at the Times that the new analysis was a "very clever way to do things."