“In two February preprint papers, first reported by the New York Times, researchers traced the spread of the SARS-CoV-2 virus, the pathogen that causes Covid-19, in 2019 in Wuhan. One study looked at initial infections at the Huanan Seafood Wholesale Market, where the first cases were detected. The other examined the genomes of the earliest strains of the virus. Around the same time, researchers from the Chinese Centers for Disease Control and Prevention published their own findings from virus samples they collected from animals and the environment around the market in early 2020.
In addition to seafood, vendors at the market sold live animals, including those collected from remote wilderness areas.
Together, the studies connect the dots of transmission at the epicenter of the pandemic, observing that the virus likely made the leap from animals to humans more than once. “Once you understand that there were infected animals in the market, then multiple spillovers are not just a possibility, they’re what you would expect at that point,” Robert Garry, a virologist at Tulane University and a co-author on both papers, told Vox.
The studies’ conclusions contradict some early reports that the Huanan market was not the original locus of Covid-19. The results also echo how scientists think the first SARS virus spread to humans in 2002. According to Garry, they make the possibility that the outbreak began with a leak from the Wuhan Institute of Virology much less plausible.”
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“while researchers have narrowed down the location in the market where the outbreak likely began and have identified several potential animal hosts, they still haven’t found the specific animals that were infected. And though scientists have found several related viruses in the wild, they haven’t found one yet that they think could have directly spawned SARS-CoV-2.”
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“it may not be possible to find out since the specific infected animals were likely culled. “You’d have to be a time traveler or something like that to go back and see,” Garry said.”
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“The lab leak hypothesis holds that SARS-CoV-2 escaped from the Wuhan Institute of Virology, a facility roughly eight miles from the Huanan market. Proponents of the theory point to several factors. Researchers there were known to be studying bat coronaviruses. Specifically, they documented a bat coronavirus called RaTG13. Discovered in 2013, it has a genetic sequence with 96 percent overlap with SARS-CoV-2.
Scientists at the Wuhan Institute were also conducting experiments under lower safety conditions than most scientists would recommend for respiratory viruses. Some researchers argue that the types of experiments they were conducting constitute gain of function, where a virus is engineered to become more infectious.
Circumstantially, pathogens have escaped from Chinese laboratories before. And the Chinese government’s actions have added to the suspicions. They may have covered up the extent of the original outbreak, and international investigators have complained that the Chinese government still has not been fully transparent with what happened during the early days of the outbreak.
However, there appears to be no evidence the Wuhan Institute of Virology had an actual isolated sample of SARS-CoV-2, nor did they have any live ancestor to the virus, including RaTG13. They only recorded the genetic sequence.
The latest studies show also that the earliest clusters of the virus were concentrated in a specific area of the Huanan market. If the virus were introduced by a person from outside the market, environmental samples testing positive for SARS-CoV-2 would likely have been spread out more through the building.
In addition, the fact that two distinct lineages emerged in the early outbreak would require that someone from the lab would have had to introduce two different versions of the virus to the lab on two separate occasions.
“The simplest explanation is that infected animals infected people,” Garry said. “You have to go through quite a bit of mental gymnastics to go ‘it came from the lab to the market,’ and you have to believe that happened twice.””
https://www.vox.com/22961822/covid-19-origin-coronavirus-wuhan-china-market-lab-leak