International scientists, who have examined previously unavailable genetic data from China, say they have found clues that the COVID-19 pandemic originated from animals as opposed to a laboratory.
The data came from samples collected at a market in the Chinese city of Wuhan close to where the first human cases of the virus were first detected.
However, other scientists have not yet verified the analysis and it has not yet been published in a peer-reviewed journal.
The World Health Organisation acknowledged the new findings but said there is more work to be done.
This “data do not provide a definitive answer to how the pandemic began, but every piece of data is important to moving us closer to that answer,” explained WHO Director-General Tedros Adhanom Ghebreyesus at a Friday press briefing.
He also criticised China for not sharing the genetic information earlier, adding “this data could have and should have been shared three years ago.”
The samples were collected from surfaces at the Huanan seafood market in Wuhan after the first human cases of COVID-19 were found in late 2019.
Tedros said the genetic sequences were uploaded to the world’s biggest public virus database in late January by scientists at the Chinese Centre for Disease Control and Prevention.
The data have since been removed from the database.
A French biologist spotted the information by chance while scouring the database and shared it with a group of scientists based outside China and looking into the origins of the coronavirus.
Genetic sequencing data showed some of the samples, which were known to be coronavirus positive, also contained genetic material from raccoon dogs, indicating the animals may have been infected by the virus, according to the scientists.
Their analysis was first reported in The Atlantic.
“There’s a good chance that the animals that deposited that DNA also deposited the virus,” said Stephen Goldstein, a virologist at the University of Utah who was involved in analysing the data.
“If you were to go and do environmental sampling in the aftermath of a zoonotic spillover event … this is basically exactly what you would expect to find.”
Ray Yip, an epidemiologist and founding member of the US Center for Disease Control office in China, said even though the new findings weren’t definitive, they were significant.
“The market environmental sampling data published by China CDC is by far the strongest evidence to support animal origins,” Yip told the AP in an email. He was not connected to the new analysis.
Scientists have been looking for the origins of the COVID-19 pandemic since the virus first emerged, but that search has been complicated by factors including the massive surge of human infections in the pandemic’s first two years and an increasingly bitter political dispute.
It took virus experts more than a dozen years to pinpoint the animal origin of SARS, a related virus.
After a weeks-long visit to China to study the pandemic’s origins, WHO released a report in 2021 concluding that COVID most probably jumped into humans from animals, dismissing the possibility of a lab origin as “extremely unlikely.”
But the U.N. health agency backtracked the following year, saying “key pieces of data” were still missing.
In recent months, WHO director Tedros has said all hypotheses remained on the table, while he and senior officials pleaded with China to share more data about their COVID-19 research.