Dozens of top experts worldwide have refuted the claims that the novel coronavirus escaped from the Wuhan Institute of Virology (WIV), and reiterated that SARS-CoV-2 most likely originated in nature.

In a pre-print review titled "The Origins of SARS-CoV-2: A Critical Review" published on the open-access research repository Zenodo on Wednesday, a group of 21 virus experts from the United States, Britain, Australia, New Zealand and other countries noted that theories about a lab leak are almost based on coincidence, not hard evidence.

They noted that the epidemiological history of COVID-19 is comparable to previous outbreaks of coronaviruses, which all have zoonotic origins.

"All previous human coronaviruses have zoonotic origins, as have the vast majority of human viruses. The emergency of SARS-CoV-2 bears several signatures of these prior zoonotic events," read the paper, adding that clear similarities are there between SARS-CoV-2 and SARS-CoV, which caused SARS outbreak in 2003.

The experts also dismissed the lab leak theory as "the emergency of SARS-CoV-2 differs markedly from documented laboratory escapes."

"No previous epidemic has been caused by the escape of a novel virus and there is no data to suggest that the WIV – or any other laboratory – were working on SARS-CoV-2, or any virus close enough to the progenitor, prior to the COVID-19 pandemic," said the paper.

It added that the viral genomic sequencing without cell culture performed at the WIV represents "a negligible risk" as viruses are inactivated during RNA extraction and "no case of laboratory escape has been documented."

"I think you can make a pretty strong argument that it didn't leak from a lab," reported CNN citing Robert Garry, professor of microbiology and immunology at Tulane Medical School.

'Science, not speculation, is essential'

On Monday, another group of 24 experts jointly published a letter in the Lancet stating that "SARS-CoV-2 most likely originated in nature and not in a laboratory."

Actually, this is not the first time these scientists have elaborated their conclusions.

In February 2020, they also published a letter in the Lancet saying "the rapid, open, and transparent sharing of data on this outbreak is now being threatened by rumors and misinformation around its origins. We stand together to strongly condemn conspiracy theories suggesting that COVID-19 does not have a natural origin."

In the letter this time, they said many of them have received inquiries asking if they still support their early-2020 open letter. "The answer is clear: we reaffirm our expression of solidarity with those in China who confronted the outbreak then, and the many health professionals around the world who have since worked to exhaustion, and at personal risk, in the relentless and continuing battle against this virus. Our respect and gratitude have only grown with time."

They stressed that "the strongest clue from new, credible, and peer-reviewed evidence in the scientific literature is that the virus evolved in nature," refuting the lab leak theory as it has no "scientifically validated evidence that directly supports it in peer-reviewed scientific journals."

The experts called for careful and transparent collection of scientific information to understand how SARS-CoV-2 reached humans and to prevent future pandemics, calling allegations and conjecture "of no help."

"It is time to turn down the heat of the rhetoric and turn up the light of scientific inquiry if we are to be better prepared to stem the next pandemic, whenever it comes and wherever it begins," they added.