International researchers, examining previously unavailable genetic data from China, say they have found clues that the covid-19 pandemic originated in animals as opposed to a laboratory.
The data came from samples collected at a market in the Chinese city of Wuhan near where the first human cases of the virus were first detected.
However, other researchers have not yet verified the analysis and it has not yet been published in a peer-reviewed journal.
The World Health Organization acknowledged the new findings but said there is more work to be done.
These “data do not provide a definitive answer to how the pandemic started, but every piece of data is important in moving us closer to that answer,” WHO Director-General Tedros Adhanom Ghebreyesus explained at a press briefing on Friday.
He also criticized 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 in the Huanan seafood market in Wuhan after the first human cases of covid-19 were detected in late 2019.
Tedros said the genetic sequences were uploaded to the world’s largest public virus database in late January by researchers at the Chinese Center for Disease Control and Prevention.
The data has since been removed from the database.
A French biologist discovered the information by chance while searching the database and shared it with a group of scientists based outside China investigating the origins of the coronavirus.
Genetic sequencing data showed that some of the samples, which were known to be coronavirus positive, also contained genetic material from raccoons, suggesting the animals may have been infected by the virus, according to the researchers.
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 analyzing the data.
“If you were to go and do environmental sampling in the aftermath of a zoonotic spillover event … that’s basically exactly what you’d expect to find.”
Ray Yip, an epidemiologist and founder of the US Center for Disease Control’s China office, said that while the new findings were not definitive, they were significant.
“The market environmental sampling data published by the China CDC is by far the strongest evidence to support animal origin,” Yip told the AP in an email. He was not linked to the new analysis.
Scientists have been searching for the origins of the Covid-19 pandemic since the virus first appeared, but that search has been complicated by factors including the massive increase in human infections in the first two years of the pandemic and an increasingly bitter political dispute.
It took virus experts more than a dozen years to determine the animal origin of SARS, a related virus.
After a week-long visit to China to study the origins of the pandemic, the WHO released a report in 2021 that concluded that COVID likely jumped into humans from animals, dismissing the possibility of a lab origin as “extremely unlikely.”
But the UN health agency backtracked the following year, saying “key data” was still missing.
In recent months, WHO chief Tedros has said all hypotheses remained on the table, while he and senior officials pleaded with China to share more information about its research into Covid-19.