A group of 18 scientists said Thursday in a letter published in Science magazine that there isn't enough evidence to decide whether a natural origin or an accidental laboratory leak caused the Covid-19 pandemic.
Like the US government and other countries, they pleaded for a new investigation to find out where the virus came from.
The letter's organizers, Jesse Bloom, who studies virus evolution at the Fred Hutchinson Cancer Research Center in Seattle, and David Relman, a microbiologist at Stanford University, said they wanted to formulate a wait-and-see position that they will believe in by many scientists divided. Many of the signatories have not yet spoken out.
"Most of the discussion you are hearing about the origins of SARS-CoV-2 at this point, in my opinion, comes from the relatively small number of people who feel very confident about their views," said Dr. Bloom.
He added, "Anyone who makes statements about this with a high degree of certainty is only going beyond what is possible with the evidence available."
The new letter states: "Theories about accidental release from a laboratory and zoonotic spillage both remain viable."
Proponents of the idea that the virus may have leaked from a laboratory, particularly the Wuhan Institute of Virology in China that studied SARS viruses, have been active this year since a World Health Organization team released a report claiming becomes that such a leak is extremely unlikely, although the mission never examined Chinese laboratories. The team visited the Wuhan laboratory but did not examine it. A laboratory test was never part of her mandate. The report, which was produced on a mission with Chinese scientists, was criticized by the US government and others for not cooperating fully and restricting international scientists' access to information.
The new letter advocated a new and stricter investigation into the origin of the virus, involving a wider range of experts and protecting against conflicts of interest.
Contrary to other recent statements, the new letter was not rejected in favor of one scenario or another. Recent letters from a different group of scholars and international affairs experts have argued at length about the relative likelihood of a laboratory leak. Earlier statements by other scientists and the W.H.O. The report both claimed that a natural origin was by far the most plausible.
Michael Worobey, an evolutionary biologist at the University of Arizona, said he signed the new letter because "the youngest W.H.O. The report on the origins of the virus and its discussion led some of us to get in touch and speak about our shared desire for a dispassionate investigation into the origins of the virus. "
"I certainly respect the opinions of others who may not agree with what we said in the letter, but I felt I had no choice but to voice my concerns," he said.
Another signatory, Sarah E. Cobey, an epidemiologist and evolutionary biologist at the University of Chicago, said, "I think it is more than likely that SARS-CoV-2 emerged from an animal reservoir rather than a laboratory."
"Laboratory accidents do happen, however, and can be catastrophic," she added. “I am concerned about the short- and long-term consequences of not rigorously evaluating the possibility of a lab escape. It would be a problematic precedent. "
The list of signatories includes researchers with in-depth knowledge of the SARS virus family, such as Ralph Baric of the University of North Carolina, who worked with Chinese virologist Shi Zhengli on research into the original SARS virus at the university. Dr. Baric did not respond to attempts to reach him by email and phone.
While this group of scientists does not label researchers by name, the letter criticizes those who have also loudly advocated the theory of natural origin and cites a lack of evidence.
Kristian Andersen, a virologist at the Scripps Research Institute in La Jolla, California, was a strong proponent of the overwhelming likelihood of natural origin. He was one of the authors of a frequently cited paper in March 2020 that ruled out the likelihood of laboratory origin, largely based on the genome of the SARS-CoV-2 virus that causes Covid-19. "We do not believe that any kind of laboratory scenario is plausible," states the paper.
Dr. Speaking only for himself, Relman said in an interview that "the piece that Kristian Anderson and four others wrote, in my view, in March of last year simply provides no evidence to support their conclusions."
Dr. Andersen, who reviewed the letter in Science, said both explanations are theoretically possible. "The letter, however, suggests a false equivalence between the laboratory escape and natural origin scenarios," he said. "To date, no credible evidence has been presented to support the speculation-based laboratory leak hypothesis."
Instead, he said, the available data "is consistent with the natural occurrence of a novel virus from a zoonotic reservoir, as has been seen so many times in the past." He said he supported further investigation into the origin of the virus.
Angela Rasmussen, a virologist at the University of Saskatchewan's Vaccines and Infectious Diseases Organization, has criticized the politicization of laboratory leak theory.
She supports further research, but said that "there is more evidence (both genomic and historical precedents) that this was the result of zoonotic origin rather than a laboratory accident."