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Further investigation is needed into the possibility that the coronavirus leaked from a laboratory, a group of researchers says. Photo: Shutterstock

Jury still out on lab-leak Covid-19 origins, researchers say in Lancet letter

  • Signatories call for further investigation of controversial theory and say there is not enough evidence yet to support the natural origins hypothesis
  • The host pathway from bats to humans has not been identified, they say
A group of scientists have urged more research on the controversial theory that the coronavirus leaked from a laboratory, issuing the call in a letter in the medical journal The Lancet on Friday.

The letter was signed by 16 virologists, biologists and biosecurity specialists.

“Research-related hypotheses are not misinformation or conjecture,” they said. “Scientific journals should open their columns to in-depth analyses of all hypotheses.”

The lab leak theory suggests that Sars-CoV-2, the virus that causes Covid-19, could have escaped from a facility researching bat coronaviruses in the central Chinese city of Wuhan, where the first cases were identified.

The group also referred to the theory as a “research-related incident” that could include researchers becoming infected while collecting bat coronaviruses in the field or on the way to a lab.

Four co-authors who wrote the first draft of the letter told the South China Morning Post in a joint statement that it was in China’s interest to explore all possible pathways by which Sars-CoV-2 could have made the jump from animals to humans.

“China, like the rest of the world, should implement the necessary scientific means to resolve this issue [of the origins of Covid-19], as no country has an interest in the emergence of new epidemics,” they said.

01:15

China rejects WHO plan to revisit Covid-19 lab leak theory

China rejects WHO plan to revisit Covid-19 lab leak theory

The Lancet had previously only published letters supporting the natural origin theory, the possibility that the virus emerged in the wild and spilled over to humans, probably via the wildlife trade.

In February last year, the journal published a letter signed by 27 scientists condemning “conspiracy theories suggesting that Covid-19 does not have a natural origin”.

In July this year, 24 of those 27 scientists authored another letter also published in The Lancet that said the lab leak theory lacked “scientifically validated evidence”.

On Friday, The Lancet also published another letter authored by a group of Chinese scientists that called for the scientific community to unite behind the natural origins theory, repeating a plea made by the 24 scientists who authored the July letter.

“Since whether animal-to-human adaptation took place in or outside Wuhan remains unclear, it is reasonable to propose that the next phase of investigating the origins of Sars-CoV-2 should not entirely focus on China,” Friday’s letter from the Chinese scientists said.

“Instead, a worldwide search at different geographical locations should be carried out to identify where and when the first animal-to-human transmission occurred,” they urged.

Emails released under freedom of information requests show that the February 2020 letter was spearheaded by virologist Peter Daszak, who has worked with Shi Zhengli, a virologist at the Wuhan Institute of Virology known for her work on bat coronaviruses.

Daszak had previously been listed as the chairman of The Lancet’s origins task force but in June the journal’s website wrote that he had recused himself from this position.

The Lancet said scientific discussion and debate were an important part of the scientific process.

The Lancet journals welcome responses from readers and the wider scientific community to content published in the journals. To date, The Lancet has published many research articles, scientific exchanges and views to reflect discussions taking place within the scientific community related to the Covid-19 pandemic,” the journal said.

‘It’s only a matter of time’: bat-human virus spillovers may be very common, study finds

In the letter on Friday, the authors said “an evidence-based, independent and prejudice-free evaluation will require an international consultation of high-level experts with no conflicts of interest”.

While previous epidemics, from Middle East respiratory syndrome (Mers) to severe acute respiratory syndrome (Sars), supported the natural origins theory, there was not enough evidence in the case of Covid-19.

“After 19 months of investigations, the proximal progenitor of Sars-CoV-2 is still lacking,” they said.

“Neither the host pathway from bats to humans, nor the geographical route from Yunnan (where the viruses most closely related to Sars-CoV-2 have been sampled) to Wuhan (where the pandemic emerged) have been identified.”

05:08

Nature or lab leak? Why tracing the origin of Covid-19 matters

Nature or lab leak? Why tracing the origin of Covid-19 matters

The search for the origins of Covid-19 has stalled amid China’s refusal to allow audits of its laboratories in Wuhan, as outlined by the World Health Organization’s proposal for the second phase of its Covid-19 origins-tracing efforts.

Phase one, a four-week WHO-China joint study in Wuhan earlier this year, classified the lab leak theory as “very unlikely”.

However, WHO director general Tedros Adhanom Ghebreyesus said in July that there was a “premature push” to dismiss the lab leak theory during the joint study.

China, however, has stressed that any origin investigations must be based on science and focus on tracing animal origins and zoonotic transmission of the coronavirus.

US-China tensions over ‘lab leak’ theory hamper hunt for Covid-19 origins

Many of the signatories of Friday’s letter have written others criticising aspects of the WHO phase one study, from Daszak’s inclusion in the WHO-appointed team to Beijing’s refusal to share key data from late 2019.

In a letter published on May 14 in the journal Science, 18 scientists, including leading virologists, said the report published by those involved in the phase one study did not give “balanced consideration” to the lab leak theory.

“Only four of the 313 pages of the report and its annexes addressed the possibility of a laboratory accident,” the scientists said.

01:51

WHO team probing coronavirus origins in China visits Wuhan wet market at epicentre of virus outbreak

WHO team probing coronavirus origins in China visits Wuhan wet market at epicentre of virus outbreak
The United States has said repeatedly the origins of the pandemic could lie in a leak from a lab researching bat coronaviruses in Wuhan. In May, US President Joe Biden gave the country’s intelligence agencies 90 days to reach a conclusion but the review was inconclusive.

China maintains that the lab leak theory is a political ploy and there are signs that the origins of Covid-19 could lie outside its borders.

China has responded to calls for an investigation into the laboratories in Wuhan with its own version of the lab leak theory.

Fort Detrick, a US Army-run medical research facility in Maryland, has been the subject of a barrage of articles from China’s state-run media suggesting the research facility could have created the novel coronavirus.

Political rows hamper Covid-19 origins hunt but more China research is a top priority, says senior WHO official

In Friday’s letter, the researchers said some unusual features of the Sars-CoV-2 genome sequence suggested that they may have resulted from genetic engineering, an approach widely used in some virology labs.

“Alternatively, adaptation to humans might result from undirected laboratory selection during serial passage in cell cultures or laboratory animals, including humanised mice,” they said.

But at present there was no conclusive evidence pointing to either the lab leak or natural origins theory, they said.

“Overwhelming evidence for either a zoonotic or research-related origin is lacking: the jury is still out.”

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