by The World Health Organization on Friday chastised Chinese officials for withholding research that may link the origin of COVID-19 to wild animals, asking why the data had not been made available three years ago. and why they are missing now.
Before the Chinese data disappeared, an international team of virus experts downloaded and began analyzing the research, which appeared online in January. They say it supports the idea that the pandemic could have started when illegally traded raccoon dogs infected humans at a Wuhan seafood market.
But the gene sequences were removed from a scientific database after experts offered to collaborate on analysis with their Chinese counterparts.
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“This data could have – and should have – been shared three years ago,” said WHO Director-General Tedros Adhanom Ghebreyesus. The missing evidence “must now be shared with the international community immediately,” he said.
According to the experts reviewing it, the research offers evidence that raccoon dogs – fox-like animals known to spread coronaviruses – had left DNA in the same place in the Wuhan market as the genetic signatures of the new coronaviruses have also been discovered.
For some experts, this discovery suggests that the animals could have been infected and transmitted the virus to humans.
With huge amounts of genetic information drawn from swabs from animal cages, carts and other surfaces in the Wuhan market at the start of 2020, genetic data had been the subject of restless anticipation among virus experts since learning about it a year ago from a paper by Chinese scientists.
A French biologist discovered the genetic sequences in the database last week, and she and a team of colleagues have started mining them for clues to the origins of the pandemic.
This team has not yet published a document describing the results. But the researchers this week delivered an analysis of the material to a WHO advisory group studying the origins of COVID in a meeting that also included a presentation by Chinese researchers regarding the same data.
The analysis appeared to conflict with earlier claims by Chinese scientists that samples taken from the market that tested positive for the coronavirus had been carried by sick people alone, said Sarah Cobey, an epidemiologist and evolutionary biologist at the University of Chicago who was not involved in recent research.
“It’s just very unlikely to see that much animal DNA, especially raccoon dog DNA, mixed in with viral samples, if it’s just primarily human contamination,” Cobey said.
Questions remain as to how the samples were collected, what precisely they contained and why the evidence had disappeared. In light of the ambiguities, many scientists reacted cautiously, saying it was difficult to assess the research without seeing a full report.
The idea that a lab accident could have accidentally triggered the pandemic has become the focus of renewed interest in recent weeks, thanks in part to a new intelligence assessment from the Department of Energy and hearings held by the new leadership of the Republican House.
But a number of virus experts not involved in the latest analysis said what was known about swabs collected from the market supported the case that animals sold there sparked the pandemic.
“This is exactly what you would expect if the virus emerged from an intermediate or multiple intermediate hosts in the market,” Cobey said. “I think ecologically it’s close to a closed case.”
Cobey was one of 18 scientists who signed an influential letter in the journal Science in May 2021 calling for serious consideration of a scenario in which the virus could have spread outside of a lab in Wuhan.
On Friday, she said lab leaks continued to pose huge risks and that greater oversight of research into dangerous pathogens was needed. But Cobey added that a mounting body of evidence – relating to the clustering of human cases around the Wuhan market, the genetic diversity of viruses there and now data on raccoon dogs – bolsters the case for an origin. commercial.
The new genetic data does not appear to prove that a raccoon dog has been infected with the coronavirus. Even if that had been the case, there would remain the possibility that another animal could have transmitted this virus to humans, or even that a person infected with the virus transmitted it to a raccoon dog.
Some scientists underscored those points on Friday, saying the new genetic data did not materially change the discussion about the origins of the pandemic.
“We know it’s a promiscuous virus that infects a bunch of species,” said University of Toronto epidemiologist David Fisman, who also signed the May 2021 letter in Science.
Chinese scientists had published a study in February 2022 examining market samples. Some scientists have speculated that the Chinese researchers may have released the data in January because they were required to make it available as part of a review of their study by a scientific journal.
The Chinese study had suggested that the samples positive for the virus came from infected people, rather than animals sold in the market. This fit a narrative long promulgated by Chinese authorities: that the virus originated not just from outside the market, but from outside the country.
But the Chinese report had left clues that viral material on the market had been mixed with genetic material from animals. And the scientists said the new analysis from the international team illustrated an even stronger connection to animals.
“Scientifically, this doesn’t prove that raccoon dogs were the source, but it definitely smells like infected raccoon dogs were in the market,” said Jeremy Kamil, a virologist at Louisiana State University Health Sciences Center Shreveport.
He added, “It raises more questions about what the Chinese government really knows.”
Scientists have warned that it is unclear whether genetic material from the virus and raccoon dogs were deposited at the same time.
Depending on the stability of the genetic material of the virus and the animals, said Michael Imperiale, a virologist at the University of Michigan, “they could have been deposited there at potentially very different times.”
Still, Dr Arturo Casadevall, an immunologist at the Johns Hopkins Bloomberg School of Public Health who co-authored a recent study with Imperiale examining the origin of the coronavirus, said linking animal and viral material nonetheless adds to the evidence of a natural overflow event.
“I would say it reinforces the zoonotic idea,” he said, “that is, the idea that it came from an animal at the market.”
Absent the actual animal that first spread the virus to humans, Casadevall said, assessing the origins of an outbreak would always involve weighing the odds. In this case, the animals sold on the market were removed before researchers began collecting samples in early 2020, making it impossible to find a culprit.
Tim Stearns, dean of graduate and postgraduate studies at Rockefeller University in New York, said the latest finding was “an interesting piece of the puzzle”, although he said it was “not in itself definitive. and highlights the need for further investigation.”
For all the missing pieces, some scientists said the new findings highlight the amount of information scientists had managed to gather about the early days of the pandemic, including the home addresses of early patients and sequence data. of the market.
Theodora Hatziioannou, a virologist at Rockefeller University, said it was essential that the raw data be released. But, she said, “I think the evidence is overwhelming at this time in favor of a commercial origin.”
And the latest data, she said, “makes it even more unlikely that it started elsewhere.”
Felicia Goodrum, an immunobiologist at the University of Arizona, said finding the virus in an actual animal would be the strongest evidence of a commercial origin. But finding virus and animal material in the same swab was close.
“For me,” she said, “it’s the best thing to do.”
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