Scientists in Lancet letter call for ‘evidence-based’ evaluation of Covid lab leak theory

In a letter, published in The Lancet, scientists say no direct evidence has been found yet that supports that natural origin theory of SARS-CoV-2.

The novel coronavirus | Pixabay
Representational Image | The novel coronavirus | Pixabay file photo

New Delhi: A group of scientists have called for an “evidence-based and independent” evaluation into the possibility that SARS-CoV-2 originated from a laboratory leak, since a natural origin of the virus has still not been identified nearly two years into the pandemic.

In a letter published in The Lancet journal Friday, the scientists noted that while considerable evidence indicated that the virus originated naturally, no direct evidence has been found yet that supports that natural origin theory of SARS-CoV-2. They added that a “research-related origin” (originating from a lab) is plausible.

Written by Jacques van Helden from Aix-Marseille University in France and 15 others, the letter further cited two earlier scientific correspondences that allegedly led to a silencing of the wider scientific debate on the origins of the virus, even among science journalists.

The two articles, published in February 2020 and 5 July this year, claimed that there was overwhelming evidence to support the theory that the novel coronavirus, which caused the Covid-19 pandemic, originated in wildlife. They further condemned “conspiracy theories” that Covid-19 did not have a natural origin.

Both articles were authored by Charles Calisher from Colorado State University, British zoologist Peter Daszak, who is also president of the NGO EcoHealth Alliance, and 25 others, and were published in The Lancet.


Also read: Hundreds of viruses, decade to build: Story of Wuhan lab at centre of Covid leak suspicion


What the letter says

The Friday letter, meanwhile, argued that most proponents of the natural origin theory simply show that SARS-CoV-2 is genetically related to other naturally occurring coronaviruses but do not explain how it infected humans.

According to the authors, the study that proposes the virus passed through an animal host before infecting humans, rules out the possibility of laboratory engineering and possible leak without conclusive arguments.

The study assumed that for a virus to modify itself in a way that allows binding with human cells requires prior knowledge of which mutations can allow this to happen, which in turn requires these mutations to already exist in nature.

However, the authors noted, that this may not be entirely true, as growing generations of viruses in labs can also give rise to new mutations, which may allow them to bind with human cells better.

Moreover, they claimed, the laboratory leak of SARS-CoV-2 was dismissed based on the fact that there was a strong similarity between receptor binding domains of the virus — through it gains entry into the human cells — and pangolins, which would explain the specific mutations in the virus that allow it to jump from bats to humans.

“However, the pangolin hypothesis has since been abandoned so the whole reasoning should be re-evaluated,” the authors said.

In the past, Nipah, MERS and the 2002–04 SARS outbreak had considerable evidence to support their natural origins, which is missing for SARS-CoV-2, they added.

This is despite the fact that more than 80,000 samples were collected and tested from Chinese wildlife sites and animal farms.

The team argued that a research-related contamination could result from contact with a natural virus during field collection, transportation from the field to a laboratory, characterisation of bats and bat viruses in a laboratory or from a virus modified in a laboratory.

It further noted that hypotheses suggesting accidental leak during research activities are not misinformation and conjecture.

“More importantly, science embraces alternative hypotheses, contradictory arguments, verification, refutability, and controversy,” the authors said.

“Departing from this principle risks establishing dogmas, abandoning the essence of science, and, even worse, paving the way for conspiracy theories,” they added.

Meanwhile, the World Health Organization has asked experts to be a part of the WHO Scientific Advisory Group for the Origins of Novel Pathogens (SAGO), which, among other things, will independently evaluate the available scientific and technical findings on the origins of SARS-CoV-2.


Also read: I was sceptical of ‘lab leak’ theory. But new info, China’s cover-up made me see differently