Data from the early days of the Covid pandemic, briefly uploaded to a database by Chinese scientists, gives information on its origins, including suggesting a role for raccoon dogs in the coronavirus reaching humans, international researchers said.

The virus was first identified in the Chinese city of Wuhan in December 2019, with many suspecting a live animal market to be involved, before spreading round the world and killing nearly 7 million people to date.

International researchers published a pre-print report based on their interpretation of the data on Monday, after leaks of their findings in the media last week and a meeting with the World Health Organization involving both the Chinese and international scientists. The WHO has urged China to release more information.

The data comprised new sequences of the SARS-CoV-2 virus and additional genomic data based on samples taken from the Huanan market in Wuhan in 2020, according to the international researchers who accessed it.

The sequences showed that raccoon dogs and other animals susceptible to the coronavirus were present in the market and may have been infected, providing a new clue in the chain of transmission that eventually reached humans, they said.

“This adds to the body of evidence identifying the Huanan market as the spillover location of Sars-CoV-2 and the epicentre of the Covid-19 pandemic,” said the report.

The data from the Chinese Center for Disease Control and Prevention (CDC) had been uploaded to GISAID, the global pathogen database, ready for it to be included in a scientific paper set to be published in a major journal.

As of March 11, it was no longer accessible on the database, where it was found by the international scientists, their report said. GISAID said in a statement it was “temporarily invisible” while it was being updated ahead of the paper’s publication, in line with normal practice.

The report was written by authors including the University of Arizona’s Michael Worobey, Kristian Andersen of Scripps Research in La Jolla, California, and Florence Debarre at the Sorbonne University in Paris, France, who accessed the data.

They say they have broken no rules in accessing the data.

It was not immediately clear whether the release of their report would have any immediate impact on the data becoming accessible again, or the publication of the paper by the Chinese scientists.

The team also called for more information to be shared.

“Other raw sequencing data from environmental samples from the Huanan market exist and could contain further clues,” Debarre told Reuters.

Genetic material

The Chinese CDC was not immediately available for comment.

On Monday, when asked by Reuters why the data first appeared online and then disappeared and whether the information would ultimately be shared, Chinese Foreign Ministry spokesman Wang Wenbin referred reporters to the “relevant authorities” without specifying further.

He said China had “always supported and participated in global scientific cooperation on origin tracing” and would continue to do so, but said the international scientific community also needed to share “their research on the virus originating from other regions of the world with China”.

In comparison to the leaked information last week, the report adds more detail about other animals present at the market, as well as showing that some of the SARS-CoV-2 positive environmental samples had more animal than human genetic material in them, which the researchers said was consistent with the animals being infected.

WHO officials said last week that the information was not conclusive but did represent a new lead into the investigation into Covid’s origins, and should have been shared immediately.

The UN agency has previously said that all hypotheses for Covid-19’s origins remain on the table, including that the virus emerged from a high-security laboratory in Wuhan that studies dangerous pathogens.

China denies any such link. WHO has also said that most evidence points towards the virus coming from animals, likely bats.