The World Health Organization criticized Chinese officials on Friday for withholding research that might link the origin of Covid to wild animals, asking why the data was not made available three years ago and why it is missing now.

Before the Chinese data disappeared, an international team of virus experts downloaded the research that appeared online in January and began analyzing it. They say it supports the idea that the epidemic 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 cooperate in the analysis with their Chinese counterparts.

“This data could have been – and should have been – shared three years ago,” said Dr. Tedros Adhanom Ghebreyesus, Director-General of the World Health Organization. The now missing evidence, he said, “needs the immediate involvement of the international community”.

According to experts reviewing the matter, the research provides evidence that raccoon dogs, fox-like animals known to spread coronaviruses, left behind DNA at the same spot in a Wuhan market where genetic signatures of the novel coronavirus were also discovered.

Some experts see this finding as indicating that animals may have been infected and may have passed the virus on to humans.

With the vast amounts of genetic information taken from swabs from animal cages, carts and other surfaces in a Wuhan market in early 2020, genetic data has been the focus of turbulent anticipation among virus experts since they learned about it a year ago in a paper published by Chinese scientists.

A French biologist discovered the genetic sequence in the database last week, and she and a team of colleagues have begun mining it for clues about the origins of the pandemic.

This team has not yet issued a paper outlining the findings. But the researchers presented an analysis of the material to a World Health Organization advisory group studying the origins of Covid this week at a meeting that also included a presentation by Chinese researchers on the same data.

Sarah Coby, an epidemiologist and developmental biologist at the University of Chicago, who was not involved in the study, said the analysis appeared to contradict previous claims by Chinese scientists that samples from the market that tested positive for coronavirus were transmitted by patients alone. in the last search.

“It is very unlikely that we would see this much animal DNA, especially raccoon dog DNA, mixed with viral samples, if the contamination was mostly human,” said Dr. Coby.

Questions remain about how the samples were collected, what exactly they contained and why the evidence disappeared. Given the ambiguity, many scientists reacted cautiously, saying it was difficult to evaluate the research without seeing a full report.

The idea that a laboratory accident could accidentally trigger a 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 by the new leadership in the Republican House.

But a number of virologists who were not involved in the latest analysis said what was known about the swabs collected at the market supported the case for the sale of animals there that led to the pandemic.

“This is exactly what you would expect if the virus was emerging from intermediate or multiple hosts on the market,” said Dr. Kobe. “I think in environmental terms, this is close to a closed state.”

Dr. Kobe was one of 18 scientists to sign an influential letter to Science in May 2021 urging serious consideration of a scenario in which the virus could spread from a laboratory in Wuhan.

On Friday, she said lab leaks still pose huge risks and that more oversight is needed for research into dangerous pathogens. But Dr. Kobe added that the accumulation of evidence — related to the clustering of human cases around the Wuhan market, the genetic diversity of viruses there, and now the raccoon dog data — has bolstered the case for the market’s origin.

New genetic data does not appear to prove that a raccoon dog has been infected with the coronavirus. Even if that were the case, there would still be a possibility that another animal could have passed this virus on to humans, or even that someone infected with the virus could pass it on to a raccoon dog.

Some scientists stressed those points on Friday, saying the new genetic data did not significantly change the debate about the origins of the pandemic.

“We know that it is a degenerate virus that infects a range of species,” said David Fisman, a University of Toronto epidemiologist who also signed the May 2021 letter in the journal Science.

Chinese scholars A Stady In February 2022 given market samples. Some scientists have speculated that the Chinese researchers may have published the data in January because they were required to make it available as part of a review of their study in a scientific journal.

The Chinese study suggested that the samples that tested positive for the virus came from infected people, rather than from animals sold in the market. That fits with a narrative long echoed by Chinese officials: that the virus spread not only from outside the market, but also from outside the country.

But the Chinese report left evidence that viral materials on the market had been mixed with genetic material from animals. The scientists said the new analysis by the international team showed a stronger link to animals.

“Scientifically, it’s not proven that raccoon dogs were the source, but it is certain that odors like infected raccoon dogs were on the market,” said Jeremy Kamel, a virologist at Louisiana State University Health Sciences Center in Louisiana.

He added, “It raises more questions about what the Chinese government really knows.”

The scientists cautioned that it was not clear whether the genetic material from the virus and from the raccoon dogs was deposited at the same time.

Depending on the stability of the genetic material from the virus and the animals, “it could have been deposited there at very different times,” said Michael Imperial, a virologist at the University of Michigan.

However, linking animal and viral material nonetheless added to the evidence of a natural indirect event, said Dr. Arturo Casadevall, an immunologist at the Johns Hopkins Bloomberg School of Public Health who co-authored a recent study with Dr. Imperial examining the origin of the coronavirus.

He said, “I would say it reinforces the idea of ​​zoonosis, that is, the idea that it came from an animal on the market.”

Dr. Casadevall said that in the absence of the actual animal that first spread the virus to humans, assessing the origins of an outbreak will always involve assessing the possibilities. In this case, the animals sold on the market were removed before researchers began taking samples in early 2020, making it impossible to find the culprit.

Tim Stearns, dean of undergraduate and postgraduate studies at The Rockefeller University in New York, said the latest discovery was “an interesting piece of the puzzle,” though he said it was “not definitive in and of itself and highlights the need for a more thorough investigation.”

For all the missing items, some scientists said the new findings highlight how much information scientists have been able to piece together about the beginnings of the pandemic, including home addresses of the first patients and sequencing data from the market.

It’s critical to release the raw data, said Theodora Hatziwanu, a virologist at Rockefeller University. But, she said, “I think the evidence is overwhelming right now towards the origin of the market.”

The latest data “makes it very unlikely that this will start elsewhere,” she said.

Finding the virus in a real animal would be the strongest evidence for the origin of the market, said Felicia Goodrem, an immunobiologist at the University of Arizona. But finding virus and animal material in the same swab was close.

“For me, that’s the next best thing,” she said.