The bitter debate over the origins of the COVID-19 pandemic flared up again this week with an expert panel report concluding that SARS-CoV-2 likely spread naturally in a zoonotic leap from animal to human. , without the help of a laboratory.
“Our article acknowledges that there are several 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 that the literature submitted peer-reviewed overwhelmingly supports the zoonotic hypothesis, appeared in the Proceedings of the National Academy of Sciences (PNAS) on October 10.
The story of the panel reflects the intensity of the debate. Originally convened as a task force of the Lancet COVID-19 Commission, a far-reaching effort to learn lessons from the pandemic, it was disbanded by Columbia University economist Jeffrey Sachs, chair of the commission.
Sachs said several members had conflicts of interest that would have influenced them by the hypothesis of the origin of the laboratory. Sachs and other researchers who argue that the scientific community has too cheerfully dismissed the possibility of a laboratory leak they are not persuaded 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 further investigation into the laboratory leak hypothesis. But he says zoonosis advocates haven’t provided much new data. “What we have seen is mainly the reanalysis and reinterpretation of existing evidence.”
Sachs adds that the task force report does not “Deals systematically” the possible origins of the pandemic linked to research. And he claims there was one “Rush to judgment” by the National Institutes of Health e “A small group of virologists” to reject possible research-related origins of the pandemic.
In September, The Lancet released a report from its commission that gave equal weight to both hypotheses. When Sachs launched the Lancet Origin Task Force in December 2020, he called conservation biologist Peter Daszak to lead it.
Daszak heads the nonprofit EcoHealth Alliance, which funded work on bat coronaviruses at the Wuhan Institute of Virology (WIV). As the first cases of COVID-19 were reported in Wuhan, China, some scientists suspect research conducted at WIV led to the spread of SARS-CoV-2.
Sachs came to believe that Daszak and other members of the task force who had ties to WIV and the EcoHealth Alliance could not fairly evaluate this possibility and should step down. After bitter infighting over issues such as transparency and access to information, Sachs pulled the plug from the task force in September 2021.
But the members continued to meet. “We had a distinct and diverse group of experts across a whole range of disciplines and we thought we had something to offer regardless of whether we were on the commission or not.”says Gerald Keusch, an infectious disease specialist at Boston University.
In assembling its report, the task force interviewed researchers who have different perspectives on the origin of the pandemic. It also looked into the history of RNA viruses, such as SARS-CoV-2, which naturally made zoonotic leaps and triggered outbreaks, and scoured the scientific literature for articles addressing the origins of COVID-19.
The final product overlaps with the larger Lancet Commission report. Both emphasize the need to address how forces such as increasing deforestation and the illicit trade in wildlife increase the risk of viral fallout. Both emphasize the risk of lax security measures in laboratories, as well as in field studies that hunt pathogens.
Covid-19: the two studies say different things
The PNAS authors say their literature search revealed “Substantial peer-reviewed scientific evidence” that SARS-CoV-2 has moved from bats to other wildlife, then to people in the wildlife trade, eventually causing an outbreak at the Huanan fish market in Wuhan.
In contrast, they say, relatively few peer-reviewed studies support the leak idea, and Daszak notes that much of the argument has been advanced through opinion articles.
“The most economical hypothesis is that the pandemic emerged through the animal market system,” says Daszak. “And while the evidence might be far better, it’s just good enough.”
He also agrees, however, that the question of how the pandemic started does not have a definitive answer yet. No one independently verified how viruses were handled in 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 who handled them.
“In the absence of these two critical data, you are left with what is available,” says Daszak. “What we have concluded is that the weight and quality of evidence is much higher on the idea of natural origins.”
The PNAS perspective also stands out for its recommendations on how to improve alerts that a pandemic is brewing. In a section called “Look ahead”the authors promote the “Intelligent surveillance” which would focus on transmission hotspots where humans and wildlife they come into contact frequentlyusing cutting-edge technologies to search for new viruses.
Tests now exist that can measure antibodies against a huge range of viruses, offering evidence of infections that have occurred in the past. Wastewater sampling could use novel polymerase chain reaction techniques to target both known and novel pathogens. And researchers could sample air on public transport and manure pits on farms.
“For nearly 3 years we have been running around in circles on different laboratory leak scenarios and nothing really added to this hypothesis,” says co-author Isabella Eckerle, a virologist at the University of Geneva. “We missed the opportunity to say … what can we do better next time?”
Co-author Linda Saif, a swine coronavirus researcher at Ohio State University, in Wooster, says studies on human and animal viral infections they remain too isolated and must be combined. “There is no source of funding for those right now.”
David Relman, a microbiome specialist at Stanford University who believes the different origin scenarios are equally plausible, believes the PNAS and Lancet Commission reports “Are not at all contradictory or inconsistent with each other”.
And Relman, who was interviewed by the task force, congratulates him on highlighting the need to better prepare for a new pandemic. “At the end of the day”He says, “This is true: spillovers, outbreaks and pandemics are the result of human activities, for which much greater control, awareness and insight are desperately needed.”
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