Samples that tested positive for SARS-CoV-2 were significantly associated with stalls selling live wildlife. The study also looked at swab samples taken from market surfaces like floors and cages after the Huanan market was shuttered. “Even in that scenario, with the majority of cases removed, we found that the remaining ones lived closer to the market than what would be expected if there was no geographical correlation between these earliest COVID cases and the market,” Worobey says. The result: Even when two-thirds of cases were removed, the findings were the same. To rule out any potentially lingering possibility of bias, Worobey’s team took one further step: Starting at the market, they began removing cases from their analyses, going farther in distance from the market as they went, and ran the stats again. In other words, these patients were recorded because they were in the hospital, not because of where they lived.” “None were mild cases that might have been identified by knocking on doors of people who lived near the market and asking if they felt ill. “It is important to realize that all these cases were people who were identified because they were hospitalized,” Worobey says. In an important addition to their earlier findings, Worobey and his collaborators addressed the question of whether health authorities found cases around the market simply because that’s where they looked. “It really originated at that market and spread out from there.” “This tells us the virus was not circulating cryptically,” Worobey says. While the cases from December 2019 mapped “like a bullseye” on the market, the later cases coincided with areas of the highest population density in Wuhan. This conclusion was supported by another finding: When the authors looked at the geographical distribution of later COVID cases, from January and February 2020, they found a “polar opposite” pattern, Worobey says. “In a city covering more than 3,000 square miles, the area with the highest probability of containing the home of someone who had one of the earliest COVID-19 cases in the world was an area of a few city blocks, with the Huanan market smack dab inside it,” says Worobey, who heads the ecology and evolutionary biology department. This supports the idea that the market was the epicenter of the epidemic, Worobey says, 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-lived near the market. The researchers were 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 in San Diego, California, examined the geographic pattern of COVID-19 cases in the first month of the outbreak, December 2019. The other study 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. The findings appear in two papers in the journal Science. Led by University of Arizona virus evolution expert Michael Worobey, researchers traced the start of the pandemic to the market in Wuhan, where foxes, raccoon dogs, and other live mammals susceptible to the virus were sold immediately before the pandemic began. Researchers have confirmed that live animals sold at the Huanan Seafood Wholesale Market in Wuhan, China, were the likely source of the COVID-19 pandemic that has claimed 6.4 million lives since it began nearly three years ago.

Covid origin