New study bolsters theory coronavirus emerged from the wild

Two new studies provide more evidence that the coronavirus pandemic originated in a Wuhan market in China where live animals were sold – advancing the theory that the virus escaped from a Chinese laboratory rather than in the wild. emerged.

Research published online on Tuesday by the journal Science shows that the Huanan seafood wholesale market was an early epicenter of the crisis, which has now killed some 6.4 million people worldwide. Scientists have concluded that the virus that causes COVID-19, SARS-CoV-2, probably spread from animals to people at two different times.

“All this evidence tells us the same thing: it points to this particular market in the middle of Wuhan,” said study co-author Kristian Andersen, a professor in the Department of Immunology and Microbiology at Scripps Research. “I myself was fairly convinced of the lab leak until we looked at it very carefully and looked at it very closely.”

In a study that included data collected by Chinese scientists, evolutionary biologist Michael Vorobey of the University of Arizona and his colleagues estimated the locations of more than 150 of the first reported COVID-19 cases since December 2019. Used the mapping tool to apply. He also did mapping of cases. Using data from a social media app in January and February 2020 that created a channel for people with COVID-19 to get help.

He asked, “In all the places where the initial cases may have lived, where did they live? And it turns out that when we were able to see it, it was this extraordinary pattern where the highest density of cases was extremely close to the two. And Very focused on this market,” Vorobey said in a press briefing. “Importantly, this also applies to all December cases and cases with no known link to the market … and this is a sign that the virus began to spread among people who worked in the market but then to the local community.” started spreading.”

Anderson said they also found case clusters inside the market, “and that clustering is a lot, especially in parts of the market” where they now know that people were selling wildlife, such as raccoon dogs, which are infected with the coronavirus. are susceptible to infection. ,

A police officer stands guard outside the Huanan Seafood Wholesale Market where the coronavirus was detected on January 24, 2020, in Wuhan, China.

Hector Retamal/AFP/Getty

In the second study, scientists analyzed the genomic diversity of viruses inside and outside China, beginning with the earliest sample genomes in December 2019 and extending to mid-February 2020. They found that two lineages – A and B – marked the beginning of the epidemic. Wuhan. Study co-author Joel Wertheim, a viral evolution specialist at the University of California, San Diego, pointed out that lineage A is genetically similar to bat coronaviruses, but lineage B appears to have spread to humans earlier, especially in the market.

“Now I realize that it’s as if I just said that what happened once in a generation happened twice in short succession,” Wertheim said. But there were some conditions – such as people and animals being close to each other and a virus that could spread from animals to people and from person to person. So “the odds of spillover have been lowered in such a way that many introductions, we believe, should really be expected,” he said.

Many scientists believe that this virus passed to humans directly from bats or through some other animal. But in June, World health organization recommendation A thorough investigation into whether a laboratory accident may be to blame. Critics had said that the WHO was too quick to dismiss the lab leak theory.

“Have we rejected the laboratory leak theory? No, we haven’t,” Anderson said. “But I think what’s really important here are possible scenarios and plausible scenarios and it’s really important to understand that possible doesn’t mean equally likely.”

The origins of the pandemic remain controversial, Some scientists believe that a laboratory leak is more likely and others remain open to both possibilities. But Matthew Aliotta, a researcher in the College of Veterinary Medicine at the University of Minnesota, has in his mind that the pair of studies “put to rest, hopefully, the hypothesis of laboratory leakage.”

“Both of these studies provide really compelling evidence for the natural origin hypothesis,” said Aliotta, who was not involved in either study. Since it’s impossible to sample an animal on the market, “it’s probably as close to a smoking gun as it can be.”

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