One of the most compelling clues to the origins of the Covid-19 pandemic was uploaded without announcement to a scientific database, going unnoticed for weeks.
And then, just as suddenly, it vanished from public view.
The genetic data, from swabs taken at the Huanan seafood market in Wuhan, China, in the weeks after Covid-19 first emerged, were available online just long enough for a Parisian scientist to stumble upon them while working from her couch on a Saturday afternoon earlier this month.
“I have a bad work-life balance,” says Florence Débarre, an evolutionary biologist whose accidental discovery of the files led to confirmation for the first time that animals susceptible to the coronavirus were present at the Wuhan market.
Her findings, which she and her colleagues posted online last week, have illuminated the way forward for identifying the origins of the pandemic – as well as the treacherous path faced by scientists seeking to follow it. Since the publication, Débarre has been set upon by online mobs and received threats to her safety. “Last night, I was crying over the horrible things I’m reading about myself on social media,” she says.
Débarre, a senior researcher at France’s National Centre for Scientific Research, is one of thousands of scientists around the world attempting to trace the virus’s journey before it exploded among humans from late 2019. She was searching for data on Gisaid, a virology database, early in March when she stumbled on something unusual.
They were thousands of raw genetic sequences from swabs that Chinese scientists had taken in early 2020, from the floors, cages, walls and surfaces of the Wuhan market where the first cases of the virus were detected.
A pre-print analysis of the same swabs, released by the Chinese Centre for Disease Control and Prevention (CCDC) in February 2022 claimed they had included human DNA and coronavirus traces, but showed no evidence of the kinds of animals most likely to have been vectors for the virus.
Their findings supported arguments made by some Chinese officials that the Wuhan market was merely a site where the virus spread among humans, rather than the cradle where it made its first fateful leap from animals to people. But when Débarre and her colleagues analysed the same data, they received another result. “It was the Latin name for raccoon dog, multiple times,” she says. “It was one of the greatest emotions of my life.”
Raccoon dogs, omnivorous east Asian cousins of the fox, are highly susceptible to coronavirus infections and shed the virus in sufficient quantities to infect animals and humans around them. In other words: a suspect was confirmed to have been present at the scene.
Débarre stresses that other animal DNA was also found in the swabs, and that there is still no conclusive proof that raccoon dogs in the market were carrying the virus, or were the vehicle for its first spillover into humankind. “But now it cannot be denied that they were there,” she says.
The next step will be to investigate the illegal supply chains that brought the raccoon dogs and other animals to the Wuhan market during winter 2019 and see whether they might lead closer to the virus’s original reservoir, still suspected to be bats.
But a step forward in solving one mystery has spawned others.
In keeping with the rules of the Gisaid database, Débarre says her team had reached out to the Chinese scientists who posted the genetic data online to ask their permission to analyse it, which she said was granted. A day later, they emailed again, to share their discovery that raccoon dog DNA was present in the sequences.
The next day, the files had been made inaccessible, apparently at the request of the Chinese researchers, who include the top virologist George Gao, a former director general of the CCDC. “We were shocked,” says Débarre. “But not surprised.”
A member of her team has been in contact with their Chinese counterparts to find out why the data was locked away. “It’s a complicated story,” Débarre says delicately. “The short answer is that we’re not collaborating right now. But that collaboration was offered [by her team].”
Gisaid said in a statement that it removed the sequences from view because they were incomplete and part of a study that was still undergoing peer review, suggesting Débarre and her team might have “scooped” the Chinese scientists if they published first. Débarre has said her team made their best effort to collaborate and that their report was never intended to compete with a peer-reviewed journal article. Gao declined to respond to a request for comment.
To the storm of questions swirling around Covid-19’s origins, this latest episode has added more. Why were the results of the swabs taken in the early months of Covid-19 withheld from the scientific community for more than three years? Why did the first version of the Chinese study claim not to have found any raccoon dog DNA? And why were the genetic sequences quietly uploaded to Gisaid – left online long enough to be discovered – and then removed from public view?
Débarre is determined not to be distracted by the intrigue around her report. “I’m a scientist,” she says. “I’m not a politician, and I’m not an activist.”
It is a vital distinction, but in pursuit of an answer to arguably the most charged scientific question in the world, she is learning it may also be naive.
Since her report went online last week, Débarre has been the subject of abuse and conspiracy theories circulating online, largely among people who support the theory the virus emerged from a leak from the Wuhan Institute of Virology, located about 30 minutes away from the market. “I’m not living the best days of my life right now,” she says.
Most concerning has been a threat by a stranger who claims to know where Débarre lives. But she is also stung by the accusations that she, as a scientist, might be disloyal to the truth. “It’s horrible to have people discuss the fact you may be lying, when you’re not lying,” she says. “When you have a profession in which being truthful is essential.”
The lab-leak theory lacks hard evidence, but has been re-energised in recent weeks by reports that US government agencies have concluded it is possible, albeit with low-to-moderate confidence. The Biden administration has said it will release the evidence underlying its agencies’ assessments over the next months.
Despite the pressure, Débarre says she will continue researching the virus’s origins. “I mean, who doesn’t want to know?” she asks.
As well as shedding light on Covid, her quest might reveal the answer to that question, too.
Florence Débarre spoke to the Guardian’s daily news podcast Today in Focus for an episode featuring the Guardian’s science editor, Ian Sample, available now wherever you listen to podcasts
