As the World Health Organization (WHO) has now announced, the Scientific Advisory Group on the Origin of New Pathogens (SAGO), which is based at the health authority, discussed this Tuesday new analyses of gene sequences attributed to the almost three-year-old samples from the Huanan Seafood Wholesale Market in Wuhan. WHO chief Tedros said on Friday that the new data could not clearly answer the question of the origin of Sars-CoV-2, but every piece of the puzzle was important.

Hinnerk Feldwisch-Drentrup

Editor in the department "Nature and Science".

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Researchers from the Chinese disease control authority CDC had recently published the sequences on the international gene database called GISAID. According to a media report in the journal "Science", theoretical biologist Florence Débarre from the Paris Institute of Ecology and Environmental Sciences discovered the data at the beginning of March. Scientists from different countries downloaded and analyzed them – they found that some samples contained not only viral material from Sars-CoV-2, but also gene segments that came from different animals, especially raccoon dogs. The raccoon dog can become infected with coronaviruses and is repeatedly traded illegally on Asian animal and meat markets. Whether the animals were actually infected, however, cannot be deduced from the information available so far. The researchers around Débarre are currently preparing a publication on this topic.

Routes of infection still unclear

Due to the newly discovered gene sequences, he believes that there were infected animals on the market, said biologist Kristian Andersen of California's Scripps Research Institute to the US magazine "The Atlantic". He analyzes the new data with Débarre. Andersen had previously researched the question of corona origin and explained that this was probably natural.

For the time being, it remains unclear whether the virus was actually transmitted to humans via raccoon dogs. It is also conceivable that the animals have been infected by other species – or in humans – on the market or elsewhere. Since raccoon dogs were apparently sold on it, which have been shown to be easily infected with Sars-CoV-2, given the spread of Covid-19 at the time of sampling, it would not be surprising if they had become infected if they were not already infected.

"Nothing new" for Chinese researchers

According to Science, the researchers recently contacted George Gao, who was head of China's CDC until July 2022, and his colleagues to work with them. Shortly afterwards, the gene sequences were deleted from the database, according to GISAID due to a request from China. Gao did not answer a question about why the data was deleted, according to Science, but explained that it was "nothing new": The fact that animals were sold illegally on the market was the reason that it was closed in early 2020. The data would not answer the question of the origin of Sars-CoV-2, Gao said, according to the report – this is still open.

Previously, Chinese researchers like him had stated that no positive samples of mammals had been detected on the market. In February 2022, they had published an analysis of possibly the same samples as the one now analyzed, but without the publication having undergone an external review process. According to experts, however, a graphic in this indicated that there could have been some mixing with genetic material of different animals. The Chinese researchers said at the time that people had probably brought the virus to the market, and this only intensified the spread.

WHO calls on Beijing to be transparent

"The data could and should have been published three years ago," said WHO chief Tedros on Friday. "We continue to call on China to be transparent with the data, conduct the necessary investigations and publish the results." Understanding how the pandemic began remains "a moral and scientific imperative."

Some researchers see the data as a possible indication that Sars-CoV-2 has a natural origin. Some US authorities, on the other hand, assume that a laboratory origin is more likely – FBI chief Christopher Wray recently confirmed earlier analyses by the police department, but without citing concrete evidence.