Evidence suggests pandemic came from nature, not lab, panel says | Science
The acrimonious debate over the origins of the COVID-19 pandemic erupted again this week with an expert panel report concluding that SARS-CoV-2 likely spread naturally in a zoonotic leap from animal to man, without the aid of a laboratory.
“Our paper acknowledges that there are different possible origins, but the evidence for zoonosis is overwhelming,” says co-author Danielle Anderson, a virologist at the University of Melbourne. The report, which includes an analysis that found peer-reviewed literature overwhelmingly supports zoonotic hypotheses, appeared in the Proceedings of the National Academy of Sciences (PNAS) on October 10.
The history of the panel reflects the intensity of the debate. Originally convened as a working group of the Lancet COVID-19 Commission, a high-profile effort to learn from the pandemic, it was dissolved by Columbia University economist Jeffrey Sachs, chairman of the commission. Sachs alleged that several members had conflicts of interest that would bias them against the lab’s origin hypothesis.
Sachs and other researchers who argue that the scientific community has too blithely dismissed the possibility of a lab leak are unconvinced by the new analysis. The task force’s literature review was a good idea, says Jesse Bloom, a virologist at the Fred Hutchinson Cancer Center who pushed for more investigations of the lab leak hypothesis. But he says zoonosis proponents haven’t provided much new data. “What we’ve seen is mostly a reanalysis and reinterpretation of existing evidence.”
Sachs adds that the task force report does not “systematically address” the possible research-related origins of the pandemic. And he argues there has been a “rush to judgement” by the National Institutes of Health and “a small group of virologists” to rule out possible research-related origins of the pandemic. In September, The Lancet released a report from his commission that gave equal weight to both hypotheses.
When Sachs launched the Lancet origin working group in December 2020, he tapped conservation biologist Peter Daszak to lead it. Daszak leads the nonprofit EcoHealth Alliance, which has funded work on bat coronaviruses at the Wuhan Institute of Virology (WIV). Because the first cases of COVID-19 were reported in Wuhan, China, some scientists suspect research at WIV led to the spread of SARS-CoV-2. Sachs came to believe that Daszak and other task force members who had ties to WIV and the EcoHealth Alliance could not assess this possibility fairly and should step down. After fierce infighting over issues such as transparency and access to information, Sachs ended the task force in September 2021.
But the members continued to meet. “We had a distinguished and diverse group of experts across a range of disciplines, and we felt we had something to offer whether we were on the commission or not,” says Gerald Keusch, infectious disease specialist at the ‘Boston University.
In writing its report, the task force interviewed researchers who have different views on the origin of the pandemic. He also reviewed the history of RNA viruses, like SARS-CoV-2, which naturally made zoonotic leaps and sparked epidemics. And he scoured the scientific literature for articles discussing the origins of COVID-19.
The final product overlaps the wider range Lancet committee report. Both underscore the need to address how forces such as increasing deforestation and the illegal wildlife trade increase the risk of viral spread. Both point to the risk of lax safety measures in laboratories, as well as in field studies that look for pathogens.
But the two reports split when it came to the origin of the pandemic.
The PNAS the authors say their literature search found “considerable peer-reviewed scientific evidence” that SARS-CoV-2 jumped from bats to other wildlife and then to people dealing in wildlife, ultimately causing an outbreak at the Huanan Seafood Market in Wuhan. By contrast, they say, relatively few peer-reviewed studies support the idea of lab leakage, and Daszak notes that much of the argument has been made through opinion pieces. . “The most parsimonious hypothesis is that the pandemic emerged through the animal market system,” Daszak says. “And while the evidence could be much better, it’s good enough.”
He also agrees, however, that the question of how the pandemic began has yet to be answered conclusively. No one independently audited how viruses were handled at WIV, for example. And there are no reports of scientists testing mammals on animal farms in China that supplied the Huanan market or the humans that handled them. “Without those two critical data elements, you end up with what’s available,” says Daszak. “What we have concluded is that the weight and quality of evidence is much higher than the idea of natural origins.”
The PNAS perspective also stands out for its recommendations on how to improve warnings that a pandemic is brewing. In a section titled “Looking Ahead,” the authors promote “smart surveillance” that would focus on transmission hotspots where humans and wildlife frequently come into contact, using cutting-edge technologies to search for new viruses. There are now tests that can measure antibodies against a wide range of viruses, providing evidence of infections that have occurred in the past. Wastewater sampling could use new polymerase chain reaction techniques to fish for both known and novel pathogens. And researchers could sample the air in public transport and manure pits on farms.
“For almost 3 years, we have been going around in circles on different lab leak scenarios, and nothing has really added to this hypothesis,” says co-author Isabella Eckerle, a virologist at the University of Geneva. “We missed the chance to say… what can we do better next time? »
Co-author Linda Saif, a porcine coronavirus researcher at Ohio State University, Wooster, says studies of human and animal viral infections remain too siloed and need to be combined. “There is no funding source for these at this time.”
David Relman, a microbiome scientist at Stanford University, who thinks the different origin scenarios are equally plausible, believes that the PNAS and Lancet the reports of the commissions are “not at all contradictory or inconsistent with each other”. And Relman, who was interviewed by the task force, praises him for emphasizing the need to better prepare for a new pandemic. “At the end of the day,” he says, “it’s all true: fallout, epidemics, and pandemics are the result of human activities, for which much greater scrutiny, attention, and insight are desperately needed.” .