by The World Health Organization chided Chinese authorities on Friday for withholding research that could link the origin of COVID-19 to wild animals, asking why the data was not made available three years ago and why it is now missing.
Before the Chinese data disappeared, an international team of virus experts downloaded and began analyzing the research, which appeared online in January. They say this supports the idea that the pandemic could have started when illegally traded raccoon dogs infected humans at a seafood market in Wuhan.
But the genetic sequences were removed from a scientific database once the experts offered to collaborate on the analysis with their Chinese colleagues.
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“These data could – and should have – been shared three years ago,” said WHO Director-General Tedros Adhanom Ghebreyesus. The missing evidence now “needs to be shared with the international community immediately,” he said.
According to the experts who are analyzing it, the research offers evidence that raccoon dogs – fox-like animals known to spread coronavirus – left behind DNA in the same place in the Wuhan market where the genetic signatures of the new coronavirus also were. were discovered.
For some experts, this finding suggests that the animals may have been infected and could have transmitted the virus to humans.
With vast amounts of genetic information extracted from samples of animal cages, carts and other surfaces at the Wuhan market in early 2020, genetic data has been the focus of uneasy anticipation among virus experts since they learned of it a year ago in an article by Chinese scientists.
A French biologist discovered the genetic sequences in the database last week, and she and a team of colleagues began searching them for clues about the origins of the pandemic.
That team has yet to release a paper describing the findings. But the researchers delivered an analysis of the material to a WHO advisory group studying the origins of COVID this week at a meeting that also included a presentation by Chinese researchers on the same data.
The analysis appeared to clash with previous claims by Chinese scientists that samples collected from the market that were positive for the coronavirus had only been carried by sick people, said Sarah Cobey, an epidemiologist and evolutionary biologist at the University of Chicago, who was not involved. in recent research.
“It’s very unlikely to see so much animal DNA, especially raccoon dog DNA, mixed with viral samples if it’s simply mostly human contamination,” Cobey said.
Questions remain about how the samples were collected, what exactly they contained and why the evidence disappeared. Faced with the ambiguities, many scientists reacted with caution, saying it was difficult to evaluate 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 Energy Department intelligence assessment and hearings held by the House’s new Republican leadership.
But several virus experts not involved with the latest analysis said what is known about the swabs collected at the market strengthens the case that the animals sold there triggered the pandemic.
“It’s exactly what you would expect if the virus were emerging from one or several intermediate hosts on the market,” Cobey said. “I think ecologically, this is 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 where the virus could have come out of a laboratory in Wuhan.
On Friday, she said that laboratory leaks continue to pose huge risks and that more oversight of research on dangerous pathogens is needed. But Cobey added that an accumulation of evidence — relating to the clustering of human cases around the Wuhan market, the genetic diversity of viruses there, and now the raccoon dog data — has strengthened the case for a market origin.
The new genetic data does not appear to prove that a raccoon dog has been infected with the coronavirus. Even if it had been, the possibility remains that another animal could have passed this virus on to people, or even that someone infected with the virus could have passed it on to a raccoon dog.
Some scientists underscored those points on Friday, saying the new genetic data had not significantly changed the debate over the origins of the pandemic.
“We know it’s a promiscuous virus that infects multiple species,” said David Fisman, an epidemiologist at the University of Toronto who also signed the May 2021 letter in Science.
Chinese scientists released a study in February 2022 analyzing market samples. Some scientists have speculated that the Chinese researchers may have posted the data in January because they were required to make it available as part of a scientific journal review of their study.
The Chinese study suggested that the positive samples for the virus came from infected people, not animals sold on the market. This fits with a narrative long publicized by Chinese officials: that the virus emerged not just from outside the market, but from outside the country.
But the Chinese report hinted that the viral material on the market was mixed with genetic material from animals. And the scientists said the international team’s new analysis illustrated an even stronger link with the animals.
“Scientifically, this doesn’t prove that raccoon dogs were the source, but it sure looks like infected raccoon dogs were on the market,” said Jeremy Kamil, a virologist at the Health Sciences Center at Louisiana State University Shreveport.
He added: “It raises more questions about what the Chinese government really knows.”
The scientists cautioned 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 in 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 the link between animal and viral material, however, added to the evidence for a natural spillover. . event.
“I would say it strengthens the zoonotic idea,” he said, “that is, the idea that it came from an animal on the market.”
In the absence of the actual animal that first spread the virus to people, Casadevall said, assessing the origins of an outbreak would always involve weighing probabilities. In this case, the animals sold on the market were withdrawn before the researchers started taking samples in early 2020, making it impossible to discover a culprit.
Tim Stearns, dean of undergraduate and graduate studies at Rockefeller University in New York, said the latest finding is “an interesting piece of the puzzle”, although he said it “is not in itself definitive and highlights the need to a more thorough investigation. .”
Despite all the missing elements, some scientists said the new findings highlight how much information scientists have been able to gather about the start of the pandemic, including home addresses of initial patients and market sequence data.
Theodora Hatziioannou, a virologist at Rockefeller University, said it was critical that the raw data be released. But, she said, “I think the evidence is overwhelming right now towards a market origin.”
And the latest data, she said, “make it even more unlikely that this 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 on the same swab was close.
“To me,” she said, “this is the next best thing.”
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