Origins of Covid-19: WHO reviews new data from China

CNN
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In the search for the causes of the Covid-19 pandemic, there is a tempting new clue.

New analysis of collected genetic material From January to March 2020, the Huanan Seafood Market in Wuhan, China, found animal DNA in samples already known to be positive for SARS-CoV-2, the coronavirus that causes Covid-19. Much of that DNA appears to come from animals known as raccoon dogs known to have been sold in the market, according to World Health Organization officials who reviewed the new evidence at a briefing on Friday.

The link to raccoon dogs came to light after Chinese researchers shared raw genetic sequences taken from swabs collected from the market early in the pandemic. The sequences were uploaded at the end of January 2023 to the GISAID data exchange site but have recently been removed.

An international team of researchers spotted them and uploaded them for further study, WHO officials said Friday.

The new results, which have not yet been published, do not resolve the question of how the pandemic began. They do not prove that raccoon dogs were infected with SARS-CoV-2, nor do they prove that raccoon dogs were the animals that first infected humans.

But because viruses don’t survive long in the environment outside of their hosts, the discovery of so much virus genetic material mixed with raccoon dog genetic material is highly suggestive that they could be carriers, say the scientists working on the analysis. An analysis was made Christian Andersen, immunologist and microbiologist at Scripps Research; Edward Holmes, virologist at the University of Sydney; Michael Sparrow, evolutionary biologist at the University of Arizona. These three scientists, who have been digging into the origins of the pandemic, were interviewed by reporters from The Atlantic magazine. CNN has reached out to Andersen, Holmes and Sparrow for comment.

Detailed information about international analysis was first published on Thursday Atlantic Ocean.

The new data comes as Congressional Republicans launched an investigation into the origins of the pandemic. Previous Research provided evidence that the virus likely entered the market naturally, but was unable to point to a specific origin. Some US agencies, including the recent US Department of Energy estimatethe pandemic is said to have likely originated from a leak from a lab in Wuhan.

At a briefing on Friday, WHO Director-General Tedros Adhanom Ghebreyesus said the organization first became aware of the sequence of events on Sunday.

“As soon as we became aware of these data, we contacted the Chinese CDC and urged them to share it with the WHO and the international scientific community so that it can be analyzed,” Tedros said.

The WHO also convened its Scientific Advisory Group on the Origins of New Pathogens, known as SAGO, which is studying the causes of the pandemic, to discuss the data on Tuesday. The group heard from Chinese scientists who originally studied the sequences, as well as from a group of international scientists who took a fresh look at them.

WHO experts said at Friday’s briefing that the data is not final. They still cannot say whether the virus was leaked from the laboratory or whether it was transmitted naturally from animals to humans.

“These data do not definitively answer the question of how the pandemic began, but every piece of data is important in getting us closer to that answer,” Tedros said.

The sequences prove that China has more data that could relate to the origin of the pandemic that it has not yet shared with the rest of the world, the WHO said.

“This data could and should have been released three years ago,” Tedros said. “We continue to urge China to be transparent in data sharing, conduct necessary investigations and share results.

“Understanding how the pandemic began remains a moral and scientific imperative.”

CNN contacted the Chinese scientists who first analyzed and shared the data, but received no response.

Chinese researchers affiliated with that country’s Centers for Disease Control and Prevention shared their own analysis of samples in 2022. In this preliminary study, published last year, they concluded that “no animal carrier of SARS-CoV2 could be identified.” “.

Study examined 923 environmental samples from a seafood market and 457 samples from animals and found 63 environmental samples that tested positive for the virus that causes Covid-19. Most were taken from the western end of the market. Chinese authors wrote in 2022 that none of the animal samples taken from refrigerated and frozen food for sale, or from live stray animals roaming the market, had tested positive.

When they looked at the different kinds of DNA present in the environmental samples, the Chinese authors only saw links to humans, not other animals.

When an international team of researchers recently Taking a fresh look at the genetic material in samples taken on and around market stalls using an advanced genetic technique called metagenomics, the scientists said they were surprised to find a significant amount of DNA belonging to raccoon dogs, a small animal related to foxes. Raccoon dogs may be infected with the virus that causes Covid-19 and top the list of suspected animal hosts for the virus.

“What they found is molecular proof that the animals were sold in this market. It was suspected, but they found molecular evidence for it. And also that some of the animals that were there were susceptible to SARS-CoV2 infection, and some of those animals include raccoon dogs,” Maria Van Kerkhove, WHO technical lead for Covid-19, said at a briefing on Friday.

“This does not change our approach to studying the origins of Covid-19. It just tells us that there is more data out there and that it needs to be shared in full,” she said.

Van Kerkhove said that until more evidence can be considered by the international scientific community, “all hypotheses remain on the table.”

Some experts considered the new evidence strong, if not entirely convincing, regarding market origins.

“The data further points to a market origin,” said Andersen, an evolutionary biologist at Scripps Research who attended the WHO World Conference. meeting and is one of the scientists analyzing the new data, told the journal The science.

The claims made about the new data quickly sparked controversy in the scientific community.

François Balloux, director of the Institute of Genetics at University College London, said the fact that the new analysis has not yet been published for scientists to scrutinize but has become known in the news requires caution.

“Articles like this don’t really help as they only further polarize the debate,” Ballu wrote in a thread on Twitter. “Those who are convinced of a zoonotic origin will take this as the ultimate proof of their conviction, and those who are convinced it was a lab leak will interpret the weakness of the evidence as an attempt at a cover-up.”

Other experts not involved in the analysis said the data could be the key to showing the virus is naturally occurring.

Felicia Goodrum is an immunobiologist at the University of Arizona who recently published a review of all available data for various theories of the origin of the pandemic.

Goodrum says the strongest evidence for natural spread would be an isolation of the virus that causes Covid-19 from an animal that was on the market in 2019.

“Obviously this is not possible as we cannot go back in time any more than with sequencing and there were no animals at the time when sequences could be collected. For me, that’s the next best thing,” Goodrum said in an email to CNN.

At the WHO briefing, Van Kerkhove said the Chinese CDC researchers had uploaded the sequences to GISAID as they updated their original study. She said their first article is in the process of being updated and resubmitted for publication.

“GISAID informed us that the Chinese CDC data is being updated and expanded,” she said.

Van Kerkhove said on Friday that the WHO would like to find the origin of the animals. Were they wild? Were they grown?

She said that during the investigation into the causes of the pandemic, WHO China has been repeatedly asked to conduct research to trace the animals back to their original farms. She said the WHO also requested blood tests from people who worked at the market, as well as animal tests that may have been brought in from farms.

“Share the data,” the doctor said. Mike Ryan, executive director of the WHO health emergencies program, said on Friday, addressing scientists around the world who may have relevant information. “Let science do its job and we’ll get the answers.”