Eighteen scientists from some of the world’s most prestigious research institutions are urging their colleagues to delve deeper into the origins of the coronavirus responsible for the global pandemic.
In a letter published Thursday in the journal La science, they argue that there is not yet enough evidence to rule out the possibility that the SARS-CoV-2 virus escaped from a laboratory in China, and they call for a “proper investigation” into the matter.
“We believe that this question deserves a fair and thorough scientific investigation, and that any further judgment should be made on the available data,” said Dr David Relman, professor of microbiology and immunology at Stanford University, who contributed to the writing of the letter.
The brief letter was prompted in part by the publication on March 30 of a report commissioned by the World Health Organization which sought to uncover the origin of the virus that has killed more than 3.3 million of people around the world.
The authors of this report, which is credited to both the WHO and China, ranked each of the four possible scenarios on a scale from “extremely unlikely” to “very likely.”
After reviewing the information, data, and samples presented by Chinese team members, the authors concluded that the likelihood of the virus moving from a source animal to an intermediate species and then to humans was “likely. very likely ”, while an introduction due to an accidental laboratory leak was rated as“ extremely unlikely ”.
The researchers also considered other potential pathways: direct passage from animals to humans without an intermediate host (“possible to probable”) and transmission from the surface of frozen food products (“possible”).
But Relman and his co-authors said their colleagues who worked on the WHO investigation did not have access to enough information to draw these conclusions.
“We’re reasonable scientists with expertise in the relevant areas,” Relman said, “and we don’t see the data that says it has to be naturally occurring. “
Ravindra Gupta, professor of clinical microbiology at the University of Cambridge who signed the letter, said he wanted to review lab notes from scientists working at the Wuhan Institute of Virology, a research center where coronaviruses are found. studied. He would also like to see a list of viruses that have been used at the institute over a five-year period.
The WHO report documents a meeting between its investigators and several members of the institute, including laboratory director Yuan Zhiming, who gave the joint team a tour of the facilities.
At the meeting, representatives from WIV refuted the possibility that the coronavirus responsible for COVID-19 may have leaked from the lab, noting that none of the three lab-grown SARS-like viruses are closely related to SARS-CoV- 2.
They also pointed out that blood samples obtained from workers and students of a research group led by Shi Zhengli, a WIV virologist who studies SARS-like coronaviruses that come from bats, did not contain d anti-SARS-CoV-2 antibody, which would indicate a current or past infection.
But Relman said that as a scientist he needed more than this third-hand account to rule out the possibility of an accidental lab leak. (He and his colleagues did not suggest that a potential leak was intentional.)
“Show us the test you used: What was the method? What were the results and the names of the people tested? Did you test a control population? Relman said. “In any case, it was not an adequate and detailed presentation of the data that would allow an outside scientist to come to an independent conclusion. “
Tedros Adhanom Ghebreyesus, the director-general of WHO, expressed a similar opinion when the report was first released.
“Although the team concluded that a lab leak is the least likely hypothesis, it requires further investigation, possibly with additional missions involving specialist experts, which I am prepared to deploy,” he said. he said in a speech to WHO member states on March 30. “Let me make it clear that when it comes to WHO, all assumptions remain on the table. “
Michael Worobey, who studies viruses at the University of Arizona to understand the origin, emergence and control of pandemics, also signed the letter. Since the start of the pandemic, he had considered two possibilities for how it could have started – either as an escape from a laboratory or as a natural transmission from animal to human.
Fifteen months later, he is still open to both possibilities.
“There just hasn’t been enough definitive evidence anyway,” he said, “so both remain on the table for me. “
In his own lab, Worobey is working with a graduate student who collects viruses from bats in the wild, and he’s given a lot of thought to how this research might create an ecological avenue to introduce a new pathogen to humans.
“As a person doing this, I’m very aware of the openness that creates for new viruses to come close to humans, and so I think that’s another reason I take this seriously,” he said. he declared. “I worry about this in my own work. “
Other scientists have convincingly shown that SARS-CoV-2 is not a lab construct genetically modified to make it more transmissible to humans, Worobey said. But that doesn’t rule out the possibility that an unmodified virus collected by scientists in the field and brought into a lab may have moved into humans.
“I didn’t see any evidence that I could look and say, ‘Oh, OK, that certainly disproves the accidental origin of the lab and makes it virtually 100% sure that this was a natural event,’ did he declare. “Until we get to the stadium, both possibilities are viable. “
Scientists said there was conclusive evidence that the virus had indeed spread to humans through a natural event – the discovery of the wild animals that caused the virus.
Akiko Iwasaki, professor of immunobiology and epidemiology at Yale University, noted that the WHO report mentioned the analysis of more than 80,000 samples of wild animals, livestock and poultry taken from 31 provinces of China. None of these tests revealed antibodies to SARS-CoV-2 or extract of genetic material from the virus before or after the SARS-CoV-2 outbreak in China.
“However, it is possible that an animal tank was missed and further investigation could reveal such evidence,” said Iwasaki, who also signed the letter.
David Robertson, head of viral genomics and bioinformatics at the University of Glasgow, was not among the signatories of the letter. He said he didn’t understand the point.
“No one is saying that a lab accident is not possible – there is simply no evidence of this beyond the Wuhan Institute of Virology in Wuhan,” he said.
Robertson said viruses naturally migrate from animals to humans all the time, and SARS-CoV-2 could have been one of them.
Although he agreed with the authors of the letter that finding the origins of SARS-CoV-2 was essential to prepare for the next pandemic, “wasting time investigating labs is a distraction,” he said. he said.
Relman doesn’t see it that way.
“If it turns out to be of natural origin, we will have a little more information about the location of this natural reservoir and how to pay more attention to it in the future,” he said. “And if it’s a lab, then we’re talking about thinking a lot more seriously about the types of experiments we’re doing and why. “
The authors of the letter noted that in this time of anti-Asian sentiment in some countries, it was Chinese doctors, scientists, journalists and citizens who shared crucial information with the world about the spread of the virus.
“We must show the same determination in promoting an impartial and science-based discourse on this difficult but important issue,” they wrote.
Jennifer Sills et al. Investigate the origins of COVID-19, La science (2021). DOI: 10.1126 / science.abj0016
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