Researchers Release Report Claiming China's Outbreak May Have Started in September
A new study estimates that the first human cases of COVID-19 in China may have occurred as early as September.
China has admitted that the disease was present in Wuhan, the capital of its Hubei Province, in December, although for weeks into January it denied that human-to-human transmission had already taken place.
Some reports have said that, according to internal Chinese documents not shared with the West, cases of the virus existed as early as November.
But now, according to the U.K. Daily Star, a University of Cambridge geneticist and his research team are arguing even that timetable could be off by as much as two months.
All viruses mutate. Cambridge geneticist Peter Forster has been tracking the subtle mutations of the novel coronavirus, hoping to find — based on the DNA of the virus in those who were infected in December — how far back the trail of mutations will lead him.
“The virus may have mutated into its final ‘human-efficient’ form months ago, but stayed inside a bat or other animal or even human for several months without infecting other individuals,” Forster said, according to the Daily Star.
“Then, it started infecting and spreading among humans between September 13 and December 7,” he said.
“The viral network we have detailed is a snapshot of the early stages of an epidemic, before the evolutionary paths of COVID-19 become obscured by vast numbers of mutations. It’s like catching an incipient supernova in the act,” he said according to a report on the University of Cambridge’s website.
Forster’s work uses what’s known as phylogenetic network, which maps the global movement of any living thing through the mutation of its genes.
Such a network can “reconstruct infection paths where they are unknown and pose a public health risk,” the study in the Proceedings of the National Academy of Sciences said.
The study found that “the first virus genome that was sampled on 24 December 2019 already is distant from the root type according to the bat coronavirus outgroup rooting,” it said.
“What we reconstruct in the network is the first significant spread among humans,” Forster said.
He estimates that by the time the virus reached humans, it had already gone through hundreds of mutations, which leads him to believe that the virus was prevalent in animals for years before it infected humans.
Forster said that based on his research, the virus might not have originated in Wuhan.
“If I am pressed for an answer, I would say the original spread started more likely in southern China than in Wuhan,” Forster said.
“But proof can only come from analyzing more bats, possibly other potential host animals, and preserved tissue samples in Chinese hospitals stored between September and December. This kind of research project would help us understand how the transmission happened, and help us prevent similar instances in the future,” he said.
The study was a unique use of the research tools that can trace mutations, Forster said.
“There are too many rapid mutations to neatly trace a COVID-19 family tree. We used a mathematical network algorithm to visualize all the plausible trees simultaneously,” he said.
“These techniques are mostly known for mapping the movements of prehistoric human populations through DNA. We think this is one of the first times they have been used to trace the infection routes of a coronavirus like COVID-19,” he said.
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