Scientists in China have claimed that coronavirus may have originated in India or Bangladesh as they try to shift the blame from Wuhan.
A paper by researchers at the Shanghai Institute for Biological Sciences suggests the virus existed on the Indian subcontinent before the Wuhan outbreak in December last year - but the theory is disputed.
The research, entitled ‘The Early Cryptic Transmission and Evolution of Sars-Cov-2 in Human Hosts’, challenges general orthodoxy among scientists that the virus originated in the wet markets of Wuhan.
It was posted on SSRN.Com, the preprint platform of the respected medical journal The Lancet, on November 17 and bases its findings on research into strains of the virus provided by 17 different countries.
The research, led by Dr Shen Libing, claimed the traditional approach to tracing the origin of coronavirus strains did not work as it used a bat virus discovered in Yunnan, southwest China, several years ago.
Scientists use this as an ancestral reference to examine the evolutionary history of the bug but the bat virus is not the human virus’ ancestor.
In the paper, the researchers claim this prevents scientists from tracing the origins of the pandemic.
Instead, they used a new method which involves counting the number of mutations in each viral strain.
They claim that the strains with the most mutations have been around for a longer time, and those with fewer mutations are closer to the original ancestor of Covid-19.
The paper claims that the least mutated strain was found in eight countries: Australia, Bangladesh, Greece, the US, Russia, Italy and the Czech Republic.
It also states that the area of the first outbreak should have the greatest genetic diversity - and cites India and Bangladesh.
The researchers propose that India’s young population, extreme weather and drought created the necessary conditions for the virus to jump to humans.
The researchers write: “Our result shows that Wuhan is not the place where human-to-human SARS-CoV-2 transmission first happened."
It adds: “Both the least mutated strain’s geographic information and the strain diversity suggest that the Indian subcontinent might be the place where the earliest human-to-human SARS-CoV-2 transmission occurred, which was three or four months prior to the Wuhan outbreak.”
It is worth nothing that the findings are still a preprint and are yet to be peer reviewed- so should not be seen as established conclusions.
Indian scientists have also challenged the findings of the Shanghai study.
Mukesh Thakur, a virologist working with the Indian government, told the South China Morning Post the conclusions were a “misinterpretation”.
And Marc Suchard, professor in human genetics and biostatistics at UCLA, said that the’ “arbitrary collection” of viral strains used was “unlikely to yield the progenitor”.
He acknowledged the method “holds great promise” but said it “comes with considerable uncertainty”.
Dr Shen has said he welcomes scrutiny of his paper, adding: “Only by doing so can it be rightfully refuted or accepted.”
It is generally accepted among scientists that the virus was first transmitted from an animal to a human in Huanan Seafood Wholesale Market in Wuhan, where wild animals - including bats, marmots and snakes - were traded illegally.
Scientists are still hunting for the animal source of Covid-19, which remains shrouded in mystery - though research from the Wuhan Institute of Virology earlier this year suggested the virus’ genetic makeup was identical to the coronavirus found in bats.
The emergence of the virus prompted a draconian three-month shutdown of Hubei province from January 23 - though it later spread to 218 countries and infected over 61 million people worldwide.
BLAME GAME
The pandemic has also caused significant diplomatic tension between the West and Beijing, with leaders including President Donald Trump accusing Beijing of preventing a transparent investigation into the virus and alleging a cover-up.
President Trump even told reporters in May he had seen evidence that the virus had originated in a Wuhan lab - though this theory is highly disputed by scientists.
On the campaign trail in August ahead of the US election, President Trump also said it was a "disgrace" that China had limited the spread of the virus at home but allowed it to reach the rest of the world.
In stark contrast to the US and Europe, China - with the world’s largest population - has largely returned to normal life and has reported only sporadic coronavirus outbreaks since May.
