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In the final end of the debate over the origins of the coronavirus, a group of scientists this week presented a review of scientific findings that they say show that natural animal-to-human overflow is a much more likely cause. pandemic than a laboratory incident.
Among other things, scientists cite a recent report showing that markets in Wuhan, China had sold live animals susceptible to the virus, including palm civets and raccoon dogs, in the two years before the start of the pandemic. They observed the striking similarity that the emergence of Covid-19 had with other viral diseases that occurred by natural fallout, and pointed to a variety of newly discovered viruses in animals that are closely related to the one that has caused the new pandemic.
The back and forth between scientists is taking place as intelligence agencies work with a late-summer deadline to provide President Biden with an assessment of the origin of the pandemic. There is now a division among intelligence officials as to the most likely viral scenario.
The new article, which was posted online Wednesday but has yet to be published in a scientific journal, was written by a team of 21 virologists. Four of them also collaborated on a 2020 article in Nature Medicine that largely ruled out the possibility that the virus had become a human pathogen through manipulation in the lab.
In the new paper, scientists have provided more evidence for the virus having spilled over from an animal host outside of a laboratory. Joel Wertheim, virologist at the University of California, San Diego, and co-author, said an important point supporting a natural origin was the “strange similarity” between the Covid and SARS pandemics. Both viruses appeared in China in late fall, he said, with the first known cases appearing near city animal markets – Wuhan in the case of Covid and Shenzen in the case of SARS.
In the SARS outbreak, the new document points out that scientists have finally traced the origin of viruses that infected bats far from Shenzen.
Based on the distribution of viruses similar to the novel coronavirus across Asia, Dr Wertheim and colleagues predict that the origin of SARS-CoV-2 will also be far from Wuhan.
Since its first appearance in the last months of 2019, the viral culprit of this pandemic has not yet been found naturally in any animal.
In May, another team of 18 scientists released a letter saying the possibility of a lab leak should be taken seriously because there was too little evidence to support a natural origin of the coronavirus or a leak from one. laboratory. Wuhan, where the pandemic was first documented, is home to the Wuhan Institute of Virology, or WIV, where researchers have been studying bat coronaviruses for years.
One of the signatories of the May 2021 letter, Michael Worobey of the University of Arizona, has become a co-author of the new article arguing for a natural overflow.
He said his views have evolved as more and more information emerges. Among other reasons for Dr Worobey’s change was the growing evidence of the Huanan Animal Market in Wuhan. When the pandemic first appeared in Wuhan, Chinese authorities tested hundreds of samples of animals sold in the market and did not find the coronavirus in any of them.
But last month, a team of researchers presented an inventory of 47,381 animals of 38 species sold in Wuhan markets between May 2017 and November 2019. It included species like civets and raccoon dogs that can serve as hosts. intermediates for coronaviruses.
Dr Worobey called the study a “game changer”.
He also highlighted the timing of the first Covid cases in Wuhan. “Huanan Market is right at the epicenter of the outbreak, with subsequent cases then radiating out into space from there,” Dr Worobey said in an email.
“No early cases cluster near the WIV, which has been the subject of most speculation about a possible escape from the lab,” he said.
Other scientists, however, say such arguments are speculative and that the new journal is mainly a rehash of what was already known.
“Basically it really comes down to an argument that because almost all previous pandemics were natural in origin, so has this one,” said David Relman, a microbiologist at Stanford University who has organized the May letter to Science.
He noted that he did not oppose the hypothesis of natural origin as a plausible explanation for the pandemic origin. But Dr Relman believes the new paper presents “a selective sampling of results to defend one side.”
Dr Worobey and his colleagues also presented evidence in their new paper against the idea that so-called gain-of-function research that intentionally alters a virus’s function could have played a role in the pandemic. Researchers argue that the coronavirus genome shows no convincing signature to be manipulated. And the diversity of coronaviruses scientists have discovered in Asian bats could have served as an evolutionary source for Covid-19.
But Richard Ebright, a molecular biologist at Rutgers University and persistent critic of attempts to decrease the likelihood of a lab leak, said it was a flawed argument.
Dr Ebright said it was possible that an employee of the WIV lab contracted the coronavirus while on a field trip to study bats or while processing a virus in the lab. The new document, he argued, did not address such possibilities.
“The review does not advance the discussion,” said Dr Ebright.
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