“Everything upstream of this — which animals, where do they come from, how it’s all connected — is completely unknown at this stage,” Kristian Andersen, an immunologist at Scripps Research, said in a media briefing 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’ doesn’t mean equally likely,” Andersen said. .
A natural origin of the pandemic—a “zoonosis”—has long been a favored theory among scientists for the simple reason that most pandemics, including the 2002-2003 SARS coronavirus outbreak, started that way. Andersen and his colleagues believe that multiple lines of evidence, including the clustering of early cases of Covid-19 around the market, make a market origin not only a likely scenario, but the only one that fits the data.
The suspicion of a “lab leak” was initially dismissed as a conspiracy theory in most mainstream media. There are numerous leakage scenarios in labs, and many have focused on the Wuhan Institute of Virology, a major research center that studies coronaviruses.
Scientists there say they have never had the virus in their lab. But outside experts questioned whether the lab adhered sufficiently to safety measures when investigating viruses. The Chinese authorities have restricted access to the labs by outside researchers. Amateur sleuths created online communities that steadily raised suspicions about a possible lab leak. The push to investigate the hypothesis came amid the scientific community’s struggle to establish how the virus entered the human population.
In May 2021, Science magazine published a letter from 18 scientists calling for an investigation into the origin of the virus, including exploration of the laboratory leak theory. Shortly afterwards, President Biden asked his intelligence agencies to investigate all possible causes of the pandemic. The review concluded that the virus was not an engineered bioweapon, but could not draw any further conclusions as to where it came from.
Among the scientists who signed the letter to Science was Michael Worobey, an evolutionary virologist at the University of Arizona, who felt the lab leakage thesis deserved attention, even if it wasn’t the most likely origin. But Worobey soon became convinced that the virus was off the market. Worobey is the lead author of the new paper that argues that the market was the epicenter of the pandemic.
The researchers searched data on the earliest patients, many of whom had a direct link to the market or lived nearby. The geography of early spread in the community showed infections radiating out from the market’s environment, Worobey said, “It’s an insane bull’s eye.”
In addition, 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 part of the market where live animals were sold, the new study reports.
“The virus started to spread among people who worked in the market, but then spread in the surrounding local community as vendors went into local stores and infected people who worked in those stores,” Worobey suggested.
Worobey is not new in this matter. Last year he wrote a “Perspective” article in Science in which he said that the geographic clustering of things in and around the market could not be explained away as “determination bias,” meaning that the clustering was not just the result of researchers knocking on doors in that area after the market breakout was discovered.
He believes that any alternative scenario — such as a lab leak — is implausible.
“It now brings us to a point where we know that the Huanan market was the epicenter of this pandemic. That much is now certain. If others want to contradict that, they are essentially taking a pseudoscientific approach now,” Worobey said in an interview on Tuesday. “Even though you don’t have the smoking gun of ‘Yeah, we tested the raccoon dog with the virus’ in December, when you add it all up, it’s the only theory that actually 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 trying to devise one will have to be proficient in willful ignorance, a logical contortionist, or just a fabulist.”
The authors’ claim of a natural origin of the pandemic is not new: The same two articles in an earlier form were posted online in February on a “preprint” site. But at the time, they existed in peer-review limbo—something that could be reported in a news story, but didn’t have the status of studies that have survived the scrutiny of expert outsiders and magazine editors.
The second paper published Tuesday in Science reports that genetic evidence and computer modeling suggest that the virus entered the human population not just once, but multiple times by the end of 2019. Genomic analysis of early cases shows two distinct lines called A and B that must have come from separate spillovers. Both sexes were found in environmental samples taken on the market, according to a preprint paper by Chinese researchers in February.
Promoters of the lab leak theory argue that the market was more likely a superspreader site. The virus could have been brought there by someone who was infected in a lab, or someone who was exposed to an infected lab worker, for example.
The market origin argument is also based on Chinese data that may be unreliable, Jesse Bloom, a virologist at the Fred Hutchinson Cancer Research Institute, said 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 treated with a healthy grain of salt,” Bloom said.
There is no evidence that the virus or its direct ancestor was in a lab before the outbreak in Wuhan. But the ongoing mystery of the pandemic’s origins has drawn attention to the kind of virus research — including “function gain” experiments — that some critics say is too risky. The US National Institutes of Health, immersed in controversy for helping to fund some research at the Wuhan Institute of Virology, said this year it was reviewing its policies to ensure lab safety and security.
sen. Rand Paul (R-Ky.), who is a proponent of a lab-origin statement, said at an April 30 meeting in Kentucky that if Republicans take power in the Senate after the midterm elections, he will use subpoena power “to to find out at the bottom.” from where this virus came from.”
Chinese scientists have denied that the virus was present in their lab. According to Andersen and other virologists who have studied it, the virus does not appear to have been manipulated or manipulated, and its genetic features may have been produced by evolution.
Still, the controversy over coronavirus research will not abate.
Jeffrey Sachs, a Columbia University economist, heads a committee sponsored by Lancet magazine that is expected to prepare a report this fall on the pandemic, including the origins of the virus. He recently co-authored an article in the Proceedings of the National Academy of Sciences calling for an investigation into the origins of the pandemic through a “two-tier 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: “The two competing hypotheses, natural overflow and lab creation, are both viable. They must be directly related to each other. In my opinion, the lab creation hypothesis is the most straightforward and credible.”
The new papers don’t declare the case closed, but are helpful, noted David Relman, a professor of medicine and microbiology at Stanford University who was one of the signatories of the 2021 letter to Science calling for an investigation. to 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 we now know it started here. I think we can say that something interesting has happened in this part of town,” Relman said. “We don’t have any” [coronavirus] positive animals on the market.”
Andersen, the scientist at Scripps Research, has been embroiled in the controversy over the origin of viruses for more than two years. He was the lead author of an early paper, published in Nature Medicine, in which he said the virus was clearly not developed. But his first impression of the virus had been that it looked unnatural, and it was only after more research that he concluded that its features could have been produced by evolution.
On Tuesday, Andersen reiterated that he initially thought the new coronavirus likely came from a lab. But all signs are now pointing to the market, he said.
“It’s not formal evidence, again, but it’s so strong in my opinion that any other version, say a lab leak, should be able to explain all this evidence,” he said. “It just can’t.”