by The World Health Organization on Friday rebuked Chinese officials for holding back research that could link the origin of COVID-19 to wildlife, asking why the data wasn’t made available three years ago and why it’s 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 this supports the idea that the pandemic may have started when illegally trafficked raccoon dogs infected people at a fish market in Wuhan.
However, the gene sequences were removed from a scientific database after the experts offered to collaborate with their Chinese colleagues on the analysis.
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“This data could and should have been shared three years ago,” said WHO Director-General Tedros Adhanom Ghebreyesus. The missing evidence “must be shared with the international community immediately,” he said.
According to the experts reviewing it, the study provides evidence that raccoon dogs — fox-like animals known to spread coronavirus — left DNA in the same place in the Wuhan market as genetic signatures of the new coronavirus 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 swabs from animal cages, carts and other surfaces in the Wuhan market in early 2020, the genetic data has been the focus of uneasy anticipation among virus experts since they learned about it in an article a year ago 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 to the origins of the pandemic.
This team has not yet published a paper outlining the findings. But the researchers provided an analysis of the material to a WHO advisory group looking into 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 taken from the market that were positive for the coronavirus were brought in 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, particularly raccoon dog DNA, mixed with virus samples when it’s just mostly human contamination,” Cobey said.
Questions remain about how the samples were collected, what exactly they contained, and why the evidence was gone. Given the ambiguity, many scientists were reluctant to respond, saying it was difficult to assess the research without seeing a full report.
The idea that a lab accident could have inadvertently started the pandemic has returned to center stage in recent weeks, thanks in part to a new intelligence assessment of the Department of Energy and hearings by the new Republican House leadership.
However, a number of virus experts not involved in the recent analysis said what was known about the swabs collected at the market supports the case that animals sold there may have sparked the pandemic.
“It’s exactly what you would expect if the virus originated from an intermediate host or multiple intermediate hosts in the marketplace,” Cobey said. “I think ecologically this is almost a closed case.”
Cobey was one of 18 scientists who signed an influential letter in Science magazine in May 2021, calling for serious consideration of a scenario in which the virus may have leaked from a Wuhan lab.
On Friday, she said lab leaks continue to pose huge risks and that more oversight of research into dangerous pathogens is needed. But Cobey added that accumulating evidence — in terms of the human case cluster in the Wuhan market, the genetic diversity of viruses there, and now the raccoon dog data — strengthened the case for market origin.
The new genetic data does not appear to prove a raccoon dog was infected with the coronavirus. Even if this had been the case, the possibility remains that another animal could have transmitted this virus to humans, or even that someone infected with the virus could have transmitted it to a raccoon dog.
Some scientists stressed those points on Friday, saying the new genetic data hadn’t appreciably shifted the discussion about the origins of the pandemic.
“We know it’s a promiscuous virus that infects a range of species,” said David Fisman, an epidemiologist at the University of Toronto, who also signed the May 2021 letter in Science.
Chinese scientists published a study in February 2022 that looked at the market patterns. Some scientists speculated that the Chinese researchers may have released the data in January because they had to provide them as part of a scientific journal review of their study.
The Chinese study had suggested that samples positive for the virus came from infected people, not animals sold at the market. That fits with a narrative long circulated by Chinese officials: that the virus came not just from outside the market, but outside the country altogether.
But the Chinese report had left evidence that viral material on the market had been mixed with genetic material from animals. And scientists said the international team’s new analysis shows an even stronger connection to animals.
“Scientifically, it doesn’t prove raccoon dogs were the source, but it certainly smells like infected raccoon dogs are on the market,” said Jeremy Kamil, a virologist at the Louisiana State University Health Sciences Center in Shreveport.
He added, “It raises more questions about what the Chinese government really knows.”
Scientists warned that it is not clear that the genetic material of 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.”
Nonetheless, said 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, found the linking of animal and viral material to the evidence of natural spread contributed case.
“I would say it reinforces the zoonotic idea,” he said, “that is, the idea that it came from an animal in the market.”
In the absence of the actual animal that first transmitted the virus to humans, assessing the origins of an outbreak would always involve weighing probabilities, Casadevall said. In this case, animals sold at 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 is “an interesting piece of the puzzle,” although he said it “is not in itself definitive and underscores the need for more thorough investigation.”
Despite all the missing elements, some scientists said the new results showed how much information scientists were able to glean about the beginnings of the pandemic, including home addresses for early patients and sequencing data from the market.
Theodora Hatziioannou, a virologist at Rockefeller University, said it is crucial that the raw data is made public. But she said, “I think the evidence of market origin is overwhelming right now.”
And the latest data, she said, “makes it even more unlikely that this started elsewhere.”
Felicia Goodrum, an immunobiologist at the University of Arizona, said that detection of the virus in a real animal is the strongest evidence of market origin. But finding virus and animal material in the same swab was scarce.
“To me,” she said, “that’s the next best thing.”
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