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The coronavirus pandemic began with separate viral spills (at least two, but perhaps as many as two dozen) from live animals sold and slaughtered in late 2019 at the Huanan Seafood Market in Wuhan, China, according to two articles published Tuesday in the Science magazine.
The publication of the papers, which underwent five months of peer review and revisions by the authors, is unlikely to quell the rancorous debate over how the pandemic began and whether the virus emerged from a Chinese lab. And the authors acknowledge that there are many unknowns that require further investigation, particularly which animals were involved.
“Everything upstream of that (which animals, where they come from, how it’s all connected) is completely unknown at this stage,” Kristian Andersen, an immunologist at Scripps Research, said at a media conference Tuesday.
“Have we disproved the lab leak theory? No, we haven’t. Will we ever be able to? No. But there are ‘possible’ scenarios and there are ‘plausible’ scenarios. … ‘Possible’ does not mean equally likely” , Andersen said.
A natural origin of the pandemic, a “zoonosis”, has long been a favorite theory among scientists for the simple reason that most pandemics, including the SARS coronavirus outbreak of 2002-2003, have started that way. Andersen and his colleagues believe that multiple lines of evidence, including the clustering of the first cases of covid-19 in the market, make the market origin not only a likely scenario, but the only one fits the data.
The “lab leak” conjecture was initially dismissed in most mainstream media as a conspiracy theory. There are numerous lab leak scenarios and many have focused on the Wuhan Institute of Virology, a major research center that studies coronaviruses.
Scientists say they never had the virus in their lab. But outside experts questioned whether the lab sufficiently adhered to safety measures when investigating viruses. Chinese authorities limited access to laboratories for outside researchers. Hobby sleuths created online communities that raised suspicions about a possible lab leak. The push to investigate the hypothesis came amid the scientific community’s struggles to figure out how the virus entered the human population.
In May 2021, the journal Science published a letter from 18 scientists calling for an investigation into the origin of the virus that would include exploring the lab leak theory. Soon after, President Biden asked his intelligence agencies to investigate all possible origins of the pandemic. The review concluded that the virus was not an engineered biological weapon, but otherwise did not reach a conclusion about where it came from.
Among the scientists who signed the letter in Science was Michael Worobey, an evolutionary virologist at the University of Arizona who thought the lab leak thesis deserved attention even if it wasn’t the most likely source. But Worobey soon became convinced that the virus was off the market. Worobey is the lead author of the new paper that claims the market was the epicenter of the pandemic.
The researchers sought data on early patients, many of whom had direct links to the market or lived nearby. The geography of the early community spread showed infections radiating outward from the vicinity of the market, Worobey said: “It’s a crazy bull’s eye.”
Also, when the market was first identified as the site of a cluster of cases, Chinese researchers took environmental samples looking for traces of the virus. A disproportionate number of positive virus traces came from the section of the market where live animals had been sold, the new study reports.
“The virus started to spread among people working in the market, but then it started to spread to the surrounding local community as vendors went to local shops and infected people working in those shops,” Worobey suggested. .
Worobey is not new to this issue. Last year, he wrote an “Perspective” article in Science that said the geographic clustering of cases in and around the market could not be explained as “determination bias,” meaning that the clustering did not it was simply the result of researchers knocking on doors. area after the market breakout was detected.
He believes that any alternative scenario, such as a lab leak, is implausible.
“It now puts us at a point where we know that the Huanan market was the epicenter of this pandemic. That’s already been established. If others want to discuss it, they’re now essentially taking a pseudoscientific approach,” Worobey said in an interview on Tuesday. “While you don’t have the smoking gun of ‘Yes, we tested the raccoon dog with the virus in December,’ when you put it all together, it’s the only theory that really explains all the data.”
Angela Rasmussen, a virologist at the University of Saskatchewan and co-author of one of the new papers, said in an email that she agreed with Worobey: “There is no alternative explanation that fits the facts, so anyone who try to find one. you will have to become an expert in willful ignorance, a logical contortionist, or simply a fabulist.”
The authors’ claim of a natural origin of the pandemic is not new: the same two papers in an earlier form were published online in February in a “preprint” site. But at the time, they existed in a limbo of peer review, something that might be reported in a news story, but without the stature of studies that have survived the scrutiny of experts and journal editors.
The second paper published Tuesday in Science reports that genetic evidence and computer modeling suggest that the virus spilled into the human population not just once, but on several occasions in late 2019. Genomic analysis of the first cases shows two different lineages, called A and B, which must have come from separate overflows. Both lineages were found in environmental samples taken from the market, according to a preprint paper by Chinese researchers in February.
Proponents of the lab leak theory counter that the market was more likely a site of overdiffusion. The virus could have been brought there by someone infected in a lab, or someone exposed to an infected lab worker, for example.
The argument for a market origin is also based on Chinese data that may be unreliable, said Jesse Bloom, a virologist at the Fred Hutchinson Cancer Research Institute, in an interview earlier this year. He said he believes the data is “inconclusive.”
“I think the data released by the Chinese government should be taken with a healthy grain of salt,” Bloom said.
There is no evidence that the virus or its immediate ancestor was in any laboratory before the outbreak in Wuhan. But the ongoing mystery of the pandemic’s origin has drawn attention to the type of virus research, including “gain-of-function” experiments, that some critics say is too risky. The US National Institutes of Health, embroiled in controversy because it helped fund some research at the Wuhan Institute of Virology, said this year it was reviewing its policies to ensure the safety and security of the lab.
Sen. Rand Paul (R-Ky.), who favors a laboratory-origin explanation, said at an April 30 rally in Kentucky that if Republicans take power in the Senate after the mid-term elections, he will use the subpoena power to “get to the bottom of it.” where did this virus come from.”
Chinese scientists have denied that the virus was present in their laboratory. The virus, according to Andersen and other virologists who have studied it, does not appear to be engineered or engineered, and its genetic characteristics could have been produced through evolution.
Still, the controversy surrounding coronavirus research is unlikely to go away.
Jeffrey Sachs, an economist at Columbia University, is leading a commission sponsored by the journal Lancet that is expected to produce a report this fall on the pandemic, including the origin of the virus. He recently co-authored a paper in the Proceedings of the National Academy of Sciences calling for an investigation into the origins of the pandemic through a “bipartisan congressional inquiry with full investigative powers.”
On Tuesday, after Science published the two papers, Sachs said in an email that he still favors the lab leak theory: “Both competing hypotheses, natural overflow and lab creation, are viable. They should be directly compared to each other. From my point of view, the laboratory creation hypothesis is the most direct and credible.”
The new papers don’t declare “case closed,” but they are helpful, said David Relman, a professor of medicine and microbiology at Stanford University who was one of the signatories of the 2021 letter in Science calling for an investigation of all possible pandemic origins. He said he would like to see an equally thorough forensic study of the lab leak hypothesis.
“I don’t think we can say that we know now that it started here. I think we can say that something interesting happened in this part of town,” Relman said. “We don’t have one [coronavirus] positive animals in the market”.
Andersen, the Scripps Research scientist, has been embroiled in the controversy over the origin of the virus for more than two years. He was the lead author of an early paper, published in Nature Medicine, saying the virus was clearly not designed. But his first impression of the virus had been that it seemed unnatural, and only after doing further research did he conclude that its characteristics might have been produced through evolution.
On Tuesday, Andersen reiterated that he initially thought the new coronavirus probably came from a lab. But now all signs point to the market, he said.
“It’s not formal proof, again, but it’s so strong in my opinion that any other version, a lab leak for example, should be able to explain all of this evidence,” he said. “It’s just not possible.”