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After a four-week investigation into the outbreak of COVID-19, World Health Organization (WHO) researchers are looking into the possibility that the virus’s first victim came from a different Wuhan market than the one most closely associated with the pandemic.
As their visit wound down in February, researchers met an office worker named Chen who told them he had become sick in early December 2019. This would be about four days before the first cases at Huanan Seafood Market and nearly four weeks before Chinese officials announced the virus to the world.
The man had not visited the Huanan market, which became a focal point of the COVID-19 outbreak about a week later. He said his parents had visited a different market before he became sick, according to The Wall Street Journal.
If the man’s claim is correct, he could be COVID-19’s “patient zero,” the first confirmed case of the disease. Investigators told The Wall Street Journal that the man revealed his status toward the end of their meeting. They were unable to identify the market or get more details from him.
Wuhan, population 11 million, has about 400 markets, some of which, like the Huanan market, sell captive wildlife along with fish and other materials. The markets can trade items among themselves, creating the potential for a virus to transfer across the city.
Based on its structure, researchers suspect COVID-19 began in a bat — possibly one caught and handled for sale in a Wuhan market — then jumped to people through an intermediate animal. The intermediate animal remains a mystery.
Investigators found 10 stalls at Huanan selling wild animals that could have served that role, either because they were susceptible to the virus or because they came from southern China where bats carry viruses similar to COVID-19.
According to Nature magazine, Chinese researchers identified fewer than 100 people with COVID-19 symptoms between October and December 2019. Researchers tested about two-thirds of them for COVID-19 antibodies but found none.
WHO investigator Dominic Dwyer, an Australian virologist, has suggested that China test 200,000 samples from the Wuhan Blood Center to determine whether the virus was circulating among the general population in 2019.
Despite Chinese claims that the virus arrived in Wuhan on frozen food, the speed with which it spread in Wuhan at the end of 2019 suggests that it originated with the wildlife trade, according to Daszak, a zoologist and expert in diseases that move from animals to people.
Lead investigator Peter Ben Embarek told Nature the virus likely was circulating in Wuhan before Chen fell ill, because it was well established by later in December 2019. The exact time when the virus jumped from animals to people remains unclear.
“We need to do more research on the first cases,” Embarek told the Journal.
The investigative team had planned to release a preliminary report of its visit in late February, but it was delayed.