As researchers work to better understand the origins of the novel coronavirus, a new study suggests it might have been quietly spreading among humans for years before the current outbreak.
In a study, published in the journal Nature Medicine on March 17, scientists examined the origins of the novel coronavirus and explored the possibility that the virus crossed from animals into humans some time ago, before it became capable of causing disease in people.
The study, involved researchers from the US, the UK and Australia, including Edward Holmes, a researcher based at the University of Sydney who was the first to publish a genetic sequence of SARS-CoV-2.
The researchers analysed the genomic data related to the overall molecular structure, or backbone, of the new coronavirus and argued that it evolved in it natural hosts, most likely bats, before it mutated, enabling it to infect human cells.
However a second scenario put forth by the researchers, speculated on the possibility that the virus moved into humans years, possibly even decades ago, before it evolved to cause severe symptoms in people.
Under this scenario, the virus developed the deadly “genomic features ... through adaptation during undetected human-to-human transmission,” researchers wrote.
Essentially, the virus could have reached a kind of evolutionary tipping point that precipitated the current epidemic.
“Once acquired, these adaptations would enable the pandemic to take off and produce a sufficiently large cluster of cases to trigger the surveillance system that detected it,” the study said.
Dr Francis Collins, director of the US National Institute of Health, who was not involved in the research, summed it up in a recent blog post, writing: “As a result of gradual evolutionary changes over years or perhaps decades, the virus eventually gained the ability to spread from human to human and cause serious, often life-threatening disease.”
More research would be needed to know if this was actually ever the case, researchers said.
“Studies of banked human samples could provide information on whether such cryptic spread has occurred,” they wrote.
However researchers reiterated that; “Estimates of the timing of the most recent common ancestor of SARS-CoV-2 made with current sequence data point to emergence of the virus in late November 2019 to early December 2019, compatible with the earliest retrospectively confirmed cases.”
Unlikely the virus was manipulated
Coronaviruses are a large family of viruses that can cause illnesses ranging widely in severity.
As the researchers point out, SARS-CoV-2 which causes the deadly COVID-19 disease, is the seventh coronavirus known to infect humans and the third to have come from bats.
Reports earlier this month pointed towards a suspected patient zero who attended an animal market in Wuhan where the novel coronavirus is believed to have jumped from a bat, to another animal, before infecting a human.
If true, the Wuhan market where the virus is believed to have jumped to humans was located nearby an infectious disease lab, fuelling conspiracy theories that the coronavirus was engineered into existence, either by accident or as a potential bio-weapon.
The study casts immense doubt on such a theory, however, with researchers saying there is “strong evidence” that the pathogen is “not the product of purposeful manipulation”.
“Our analyses clearly show that SARS-CoV-2 is not a laboratory construct or a purposefully manipulated virus,” they wrote.
Researcher Prof Holmes, who was involved in the study, told The Sydney Morning Herald on the weekend that the current outbreak was inevitable due to the prevalence of such animal markets in places like Wuhan.
“It is blindingly obvious that we, as humans, have to change the way we interact with the animal world. We have to cut our exposure. Those markets have to go. The illegal trade in wildlife has to end,” he said.
“The whole world is now set up for a pandemic; we live in mega cities, there is transport. It's an accident waiting to happen, and it happened.”
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