Market in Wuhan likely origin of COVID: study

SINGAPORE • The first known COVID-19 case was a market vendor in the Chinese city of Wuhan, not an accountant who appeared to have no link to the market but whose case contributed to speculation the virus could have leaked from a lab, according to a U.S. study.

The origin of the SARSCoV-2 virus that causes COVID-19 remains a mystery and a major source of tension between China and the United States.

A joint study by China and the World Health Organization all but ruled out the theory that COVID-19 originated in a laboratory, saying that the most likely hypothesis was that it infected humans naturally, probably via the wildlife trade.

A WHO-led team of experts spent four weeks in Wuhan and said in a joint report in March that the SARSCoV-2 virus had probably been transmitted from bats to humans through another animal but that further research was needed.

The accountant, who was widely thought to be the first COVID-19 patient, reported that his first symptoms appeared on Dec. 16, several days later than initially known, Michael Worobey, head of ecology and evolutionary biology at the University of Arizona, said in the study published in the journal Science on Thursday.

The confusion was caused by a dental problem he had on Dec. 8.

“His symptom onset came after multiple cases in workers at Huanan Market, making a female seafood vendor there the earliest known case, with illness onset 11 December,” the study said.

It said most early symptomatic cases were linked to the market, specifically to the western section where raccoon dogs were caged, and it provided strong evidence of a live-animal market origin.

“It becomes almost impossible to explain that pattern if that epidemic didn't start there,” Worobey said.

Wuhan is home to the Wuhan Institute of Virology, where researchers conduct experiments upon coronaviruses that circulate abundantly in bats in central and southern China. The institute has been a focus of those who argue that an accidental leak from one of its research labs is the most likely source. Worobey's article immediately drew skeptical responses from two prominent scientists.

“It is based on fragmentary information and to a large degree, hearsay,” David Relman, a professor of microbiology at Stanford University, said. “In general, there is no way of verifying much of what he describes, and then concludes.”

Jesse Bloom, a computational biologist at the Fred Hutchinson Cancer Research Center in Seattle, said the quality of the data from China on early coronavirus infections is too poor to support any conclusion.

“I don't feel like anything can be concluded with high or even really modest confidence about the exact origin of SARS-CoV-2 in Wuhan, simply because the underlying data are so limited,” Bloom said.