This supports the idea that the market was the epicenter of the epidemic, Worobey said, with vendors getting infected first and setting off a chain of infections among community members in the surrounding area. Notably, the researchers found that a striking percentage of early COVID patients with no known connection to the market - meaning they neither worked there nor shopped there - turned out to live near the market. The team was able to determine the locations of almost all of the 174 COVID-19 cases identified by the World Health Organization that month, 155 of which were in Wuhan.Īnalyses showed that these cases were clustered tightly around the Huanan market, whereas later cases were dispersed widely throughout Wuhan - a city of 11 million people. The first paper, led by Worobey and Kristian Andersen at Scripps Research Institute in San Diego, California, examined the geographic pattern of COVID-19 cases in the first month of the outbreak, December 2019. The other focused on genomic sequences of SARS-CoV-2 from samples collected from COVID-19 patients during the first weeks of the pandemic in China. One study scrutinized the locations of the first known COVID-19 cases, as well as swab samples taken from surfaces at various locations at the market. Moreover, the authors conclude that the first spread to humans from animals likely occurred in two separate transmission events in the Huanan market in late November 2019.

The publications, which have since gone through peer review and include additional analyses and conclusions, virtually eliminate alternative scenarios that have been suggested as origins of the pandemic. Their findings were published Tuesday in two papers in the journal Science, after being previously released in pre-print versions in February. Led by University of Arizona virus evolution expert Michael Worobey, international teams of researchers have traced the start of the pandemic to the market in Wuhan, China, where foxes, raccoon dogs and other live mammals susceptible to the virus were sold live immediately before the pandemic began.

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