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New genetic analysis finds clues to animal origin of Covid outbreak

The World Health Organization on Friday called on Chinese health authorities to release the genetic sequence of SARS-CoV-2 the country recently downloaded from an international database, after analysis of the data showed it yielded new clues that could point to an animal origin. Covid-19 is global.

The plea comes after a group of scientists outside China analyzed the genetic sequence of the SARS-CoV-2 virus that was initially posted to the GISAID database of China’s Centers for Disease Control and Prevention late last month. The database is a site where scientists worldwide can access and share genetic sequencing and other data.

The data comes from samples taken in early 2020 around Wuhan’s Huanan animal market, which US and Chinese authorities have pointed to as a possible primary center of the outbreak.

Analysis of those samples found “molecular evidence” of animals such as raccoon dogs mixed with swabs from the same spots that shed the virus on the market itself.

Raccoon dogs are a species susceptible to SARS-CoV-2 infection that could potentially act as an intermediate host, carrying the virus to humans from bats or other sources. However, the samples only indicated that both raccoon dogs and the virus were present in the market; This is not direct evidence that the species was a carrier.

Raccoon dog - file photo

File photo of a raccoon dog

ARTERRA/Universal Image Group via Getty Images

“We need to be clear that the virus has not been detected in any animals on the market or in animal samples from the market, or that we haven’t actually found animals that have infected humans. What this does is provide clues. It provides clues to help. We understand. What could happen,” WHO’s Maria van Kerkhove told reporters on Friday’s findings.

The new data prompted international scientists to present their analysis to the WHO’s Scientific Advisory Group for the Origins of Novel Pathogens on Tuesday, as well as a meeting with the Chinese CDC researchers who initially posted the data.

It’s unclear why China’s CDC later requested that the sequences posted to GISAID be removed last month, or why they waited three years to release the data.

“Our GISAID said the data from the China CDC is being updated and expanded. But again, we’ve called directly on the China CDC to make that data fully accessible. And so it remains very basic,” Van Kerkhove said.

Chinese researchers initially posted the data as part of a publication published as a preprint last year, he said.

Researchers at China’s CDC published a preprint last year, now “under review,” that concluded the Huanan market “may act as an amplifier” for the spread of human-introduced viruses.

George Gao, lead author of the preprint and former head of the Chinese CDC, downplayed the significance of the new analysis in Science magazine. Gao said it was “known to be illegal animal trading and that’s why the market was closed immediately.”

Gao declined to comment on why the sequences were first posted and then taken down, deferring comment to GISAID. GISAID did not immediately return a request for comment

Also unanswered are questions about the new analysis, which was first reported by The Atlantic. For example, van Kerkhove declined to specify additional details about how and what animals were identified in the sequencing analysis, deferring comment to the researchers.

French scientist Florence Debare, named by The Atlantic as the researcher who initially saw the sequences, did not respond to a request for comment.

On Twitter, DeBarre wrote that they were “not planning to communicate the results before our report is complete. My current priority is to finish the report.”

But even if Chinese health authorities repost the sequences they removed from GISAID, Van Kerkhove warned that more research will be needed to understand whether the source of Covid-19 can be conclusively linked to animals sold on the market.

“We’ve repeatedly asked for research in Wuhan and Hubei and other markets across China. We’ve repeatedly asked for research to return those animals to their source farms so we can go back in time and actually see where the animals came from and if any testing was done. happened,” Van Kerkhove said.

Although scientists have discovered Evidence that suggests The possible zoonotic origin of Covid-19 – the virus originating from animals that infected humans, like previous viruses – some elements of the US intelligence community concluded It is believed that the epidemic originated from a laboratory accident.

“Based on my initial analysis of the data, I came to believe, and I still believe today, that it indicates that Covid-19 was more likely the result of an accidental lab leak than the result of a natural spillover event,” former Trump administration CDC director Dr. Robert Redfield said in a statement. said at a hearing hosted by House Republicans earlier in the month.

In an interview with CBS News on Thursday, Dr. Anthony Fauci, who helped lead the U.S. response to the pandemic, said it’s possible we may never have a definitive answer about the origins of Covid.

“There’s really no conclusive evidence,” he said. “We will never know exactly and for sure.”

More Alexander Tin

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