“All eight COVID-19 cases detected prior to 20 December were from the western side of the market, where mammal species were also sold,” the [first] study says. The proximity to five stalls that sold live or recently butchered animals was predictive of human cases… The “extraordinary” pattern that emerged from mapping these cases was very clear, said another co-author, Michael Worobey, department head of Ecology and Evolutionary Biology at the University of Arizona.
The researchers mapped the earliest cases that had no connection to the market, Worobey noted, and those people lived or worked in close proximity to the market. “This is an indication that the virus started spreading in people who worked at the market but then started that spread … into the surrounding local community as vendors went into local shops, infected people who worked in those shops,” Worobey said.
The other study takes a molecular approach and seems to determine when the first coronavirus infections crossed from animals to humans…. The researchers suggest that the first animal-to-human transmission probably happened around November 18, 2019, and it came from lineage B. They found the lineage B type only in people who had a direct connection to the Huanan market.
“All this evidence tells us the same thing: It points right to this particular market in the middle of Wuhan,” said Kristian Andersen a professor in the Department of Immunology and Microbiology at Scripps Research and coauthor of one of the studies. The AP quotes Andersen as saying “I was quite convinced of the lab leak myself until we dove into this very carefully and looked at it much closer.”
Andersen said they found case clusters inside the market, too, “and that clustering is very, very specifically in the parts of the market” where they now know people were selling wildlife, such as raccoon dogs, that are susceptible to infection with the coronavirus…. Matthew Aliota, a researcher in the college of veterinary medicine at the University of Minnesota, said in his mind the pair of studies “kind of puts to rest, hopefully, the lab leak hypothesis.”
“Both of these two studies really provide compelling evidence for the natural origin hypothesis,” said Aliota, who wasn’t involved in either study. Since sampling an animal that was at the market is impossible, “this is maybe as close to a smoking gun as you could get.”
CNN notes that Worobey also had initially thought the lab leak had been a possibility, but now says the epidemiological preponderance of cases linked to the market is “not a mirage. It’s a real thing.
“It’s just not plausible that this virus was introduced any other way than through the wildlife trade.”
To reduce the chances of future pandemics, the researchers hope they can determine exactly what animal may have first become infected and how.
“The raw ingredients for a zoonotic virus with pandemic potential are still lurking in the wild,” said Joel Wertheim, an associate adjunct professor of medicine at the University of California, San Diego. He believes the world needs to do a much better job doing surveillance and monitoring animals and other potential threats to human health.
Read more of this story at Slashdot.