Where did the novel coronavirus SARS-CoV-2 make its fateful leap from animals to humans? In the search for “ground zero” of COVID-19, the Huanan Seafood Market in Wuhan is often cited as the prime suspect. However, a growing stash of evidence is throwing some doubt on earlier reports that pinpointed this bustling wet market as the original source of the pandemic.
The first COVID-19 infections were reported at the end of December 2019 in the Chinese city of Wuhan in Hubei province (although subsequent unconfirmed reports have suggested the first person to acquire the infection was a patient from Hubei province in November 2019, if not earlier). A study, published in The Lancet in late-January, found that the 41 patients in Hubei province had developed pneumonia from a mysterious viral infection, later identified as the novel coronavirus SARS-CoV-2. At least 66 percent of these cases were shown to have had direct exposure to the Huanan Seafood Market in the weeks before falling sick.
The Huanan Seafood market seems like a likely candidate. Despite its name, the inner-city indoor market didn’t just sell seafood, but also livestock. According to unconfirmed media reports, the market also sold a wide range of live wild animals, including wolf pups, civet cats, peacocks, otters, camels, and other “exotic” species. It’s been suggested these claims of exotic animals in the market were based on old xenophobic stereotypes and used (or at least exaggerated) to fan moral panic. Nevertheless, any densely populated area with livestock would be a fitting place for an infectious disease to be transmitted from animals to humans.
However, The Lancet report also states that the first case was reported on December 1, 2019, in a patient who had no contact with the Huanan Seafood Market at all. Wu Wenjuan, a co-author of the study and a senior doctor at Wuhan’s Jinyintan Hospital, told the BBC Chinese Service that the patient was an elderly man with Alzheimer’s disease who “lived four or five buses from the seafood market, and because he was sick he basically didn’t go out.”
The genome of SARS-CoV-2 tells a similar story. A study published in the journal Nature looked at the genome sequence data for known coronavirus strains, including SARS-CoV-2, and found that there could have been “undetected circulation” of the virus in the human population for several months. This suggests that the virus had infected humans before the cluster of patients linked to the seafood market were reported.
“The scenario of somebody being infected outside the market and then later bringing it to the market is one of the three scenarios we have considered that is still consistent with the data,” Kristian Andersen, study author and an evolutionary biologist at the Scripps Research Institute, told Science. “It’s entirely plausible given our current data and knowledge.”
But if it wasn’t the Huanan Seafood Market, then where did it all start? We don’t know, and it’s not certain whether we’ll ever find out. It remains true that it currently appears that the virus first emerged in China’s Hubei province, and the Huanan Seafood Market is still a vital piece of the puzzle, but there’s currently not enough evidence to categorically pinpoint a particular time, place, and person.