How the ongoing pandemic which has claimed at least six million lives globally began remains a mystery but leading infectious disease expert Dr Anthony Fauci says a growing body of evidence suggests the virus is not the result of experiments gone awry.
Dr Fauci, who has served as the Chief Medical Advisor to seven Presidents and directed the US National Institute of Allergy and Infectious Diseases (NIAID) since 1984, has also frequently been embroiled in political and scientific debate as to the origin of the pandemic.
Speaking to Newshub Nation, Dr Fauci addressed the 'lab leak' hypothesis which claims SARS-CoV-2 - the virus which causes COVID-19 - escaped from the Wuhan Institute of Virology.
"There's always the question: was this a lab leak from things that were being done in laboratories? You want to keep an open mind and we all should keep an open mind on that," he said.
The prevailing theory internationally is that SARS-CoV-2 originated in bats before making the jump to humans, possibly through intermediary animals, somewhere in Wuhan's Huanan livestock market in late 2019.
However proponents of the lab leak theory say abnormalities in the virus, such as features of its spike protein known as a 'furin cleavage site', could indicate human tampering. A paper published in The Lancet medical journal in August last year stated finding a natural origin for certain viral traits 'has proved to be elusive'.
Researchers in the Wuhan Institute of Virology were also studying bat coronaviruses and specifically, they documented a bat coronavirus called RaTG13 with 96 percent genetic overlap with SARS-CoV-2.
While not ruling out a lab leak, Dr Fauci stressed it was not the most plausible option.
"I think when you look at the weight of the evidence that's accumulating now, it's much more likely that it was a natural occurrence," he said.
"[The virus jumped] from an animal host to a human. Likely the bat being the original and then infecting animals that were, I think, inappropriately put into a wet market in Wuhan."
Many infectious diseases are the result of 'spillover', where viruses originating in animals jump to humans. These spillover events are growing more common as natural habitats are destroyed and animals are forced into closer contact with humans.
A pair of extensive studies published in February by an international team of scientists support the spillover theory.
The team analyzed viral genes, the social media activities of early COVID patients and maps of market stalls where live animals were sold in Wuhan and concluded that SARS-CoV-2 was very likely present in live animals sold at the Huanan Seafood Wholesale Market in late 2019.
Under pressure from the Republican Party to investigate the lab leak theory, President Joe Biden directed US intelligence agencies to investigate the virus' origins in 2021.
A recently declassified report found that while they ruled out more outlandish theories - such as the virus being a deliberately engineered bioweapon - they were unable to settle on a definitive answer.
"After examining all available intelligence reporting and other information, the IC (Intelligence Council) remains divided on the most likely origin of COVID-19. All agencies assess that two hypotheses are plausible: natural exposure to an infected animal and a laboratory-associated incident," the report stated.
Regardless of how it began, the pandemic still rages across the world with China currently battling an Omicron wave and ordering fresh lockdowns.
Dr Fauci says we'll never be free of the virus entirely but he sees light at the end of the tunnel.
"When you're dealing with a highly transmissible virus, like SARS-CoV-2, I don't think we're going to eradicate or eliminate but I think we can get it to the level of control where it doesn't really significantly interfere with our function as a society. And that's where I hope we are going, in that direction."
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