by The World Health Organization on Friday chastised Chinese officials for rejecting research that could link the origin of COVID-19 to wild animals, asking why the data hadn’t been 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 it supports the notion that the pandemic may have started when illegally traded raccoon dogs infected humans at a Wuhan seafood market.
But the gene sequences were removed from a scientific database once experts offered to collaborate on the 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 now “must be shared immediately with the international community,” he said.
According to experts looking into it, the research offers evidence that raccoon dogs – fox-like animals known to spread coronaviruses – had left their DNA in the same place in the Wuhan market where the genetic signatures of the new coronavirus were also discovered. .
For some experts, this finding suggests that the animals may have been infected and may have passed the virus on to humans.
With massive amounts of genetic information taken from swabs of animal cages, trolleys and other surfaces at the Wuhan market in early 2020, the genetic data had been the focus of restless anticipation among virus experts ever since it came out. learned about 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 have begun mining them for clues about the origins of the pandemic.
That team has not yet released a paper outlining the findings. But the researchers delivered an analysis of the material to a WHO advisory group studying the origins of COVID this week in a meeting that also included a presentation by Chinese researchers on the same data.
The analysis seemed to clash with earlier claims by Chinese scientists that samples taken on the market that tested positive for the coronavirus were only ferried in 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 that much animal DNA, especially raccoon dog DNA, mixed with viral samples, if it’s simply primarily human contamination,” Cobey said.
Questions remain about how the samples were collected, what exactly they contained and why the evidence had disappeared. In light of the ambiguities, many scientists reacted cautiously, saying it was difficult to evaluate the research without seeing a full report.
The idea that a lab accident may 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 by new House leadership. republican.
But a number of virus experts not involved in the ultimate analysis said what was known about the swabs collected at the market strengthened the case that the animals sold there had triggered the pandemic.
“It’s exactly what you would expect if the virus emerged from one or more 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 urging serious consideration of a scenario in which the virus could leak from a lab in Wuhan.
On Friday, he said laboratory leaks continue to pose huge risks and that more oversight of research into dangerous pathogens is needed. But Cobey added that a buildup of evidence — related to the clustering of human cases around the Wuhan market, the genetic diversity of viruses there, and now data on raccoon dogs — bolstered the market origin thesis.
The new genetic data does not appear to prove that a raccoon dog has been infected with the coronavirus. Even if it was, the possibility remains that another animal could have passed that virus on to people, or even that someone infected with the virus could have passed it on to a raccoon dog.
Some scientists made these points on Friday, saying the new genetic data hasn’t appreciably shifted the discussion about the origins of the pandemic.
“We know it’s a promiscuous virus that infects a group of species,” said University of Toronto epidemiologist David Fisman, who also co-authored the May 2021 letter in Science.
Chinese scientists had published a study in February 2022 examining market samples. Some scientists speculated that the Chinese researchers might publish the data in January because they needed to make it available 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, rather than animals sold on the market. This fit with a narrative long promulgated by Chinese officials: that the virus arose not only from outside the market, but also from outside the country.
But the Chinese report had left hints that the viral material at the market had been confused with genetic material from animals. And the scientists said the international team’s new analysis illustrated an even stronger link to animals.
“Scientifically, it doesn’t prove that raccoon dogs were the source, but it definitely reeks of infected raccoon dogs at the market,” said Jeremy Kamil, a virologist at the Louisiana State University Shreveport Health Sciences Center.
He added, “It raises more questions about what the Chinese government really knows.”
Scientists cautioned it was unclear whether the genetic material of the virus and raccoon dogs were deposited at the same time.
Depending on the stability of the genetic material from 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.”
However, Dr. Arturo Casadevall, an immunologist at the Johns Hopkins Bloomberg School of Public Health who co-authored a recent study with Imperiale looking at the origin of the coronavirus, said linking animal and viral material still added to the evidence of a natural spillover event.
“I would say it reinforces the zoonotic idea,” he said, “that is, the idea that it comes from an animal in 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 assessing probabilities. In this case, the animals sold at the market were removed before researchers began taking samples in early 2020, making it impossible to find a culprit.
Tim Stearns, dean of graduate and undergraduate studies at Rockefeller University in New York, said the latest discovery was “an interesting piece of the puzzle,” though he said it “isn’t in itself definitive and emphasizes the need for a more thorough investigation.”
For all the missing elements, some scientists said the new findings highlighted how much information scientists were able to glean about the onset of the pandemic, including the home addresses of the first patients and sequence data from the market.
Theodora Hatziioannou, a virologist at Rockefeller University, said it was imperative that the raw data be released. But she, she said, “I think the evidence at the moment is overwhelming towards a market origin.”
And the latest data, he said, “make it even more unlikely that all of this started somewhere else.”
Felicia Goodrum, an immunobiologist at the University of Arizona, said finding the virus in a real animal would be the strongest evidence of a commercial origin. But finding viruses and animal material in the same swab was close.
“For me,” she said, “that’s the next best thing.”
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