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Most likely, the virus was a zoonotic spillover, a leap from animals to humans, which have become more common as people push into new areas where they have closer contact with wildlife. The facts are still extremely sparse. The closest-known relatives to this coronavirus were collected from bats in China’s Yunnan province in 2012 to 2013 and in 2019. The first one matches the virus genetic sequence by 96.2 percent, and the second one by 93.3 percent. But with a genome size of about 30,000 nucleotides, the closest bat virus is still nearly 1,200 nucleotides distant.
Moreover, the first outbreak was reported more than 1,000 miles away from Yunnan in Wuhan, Hubei province. How did it cross time and distance? Was there another animal intermediary? David A. Relman, a Stanford University microbiologist, writes in the Proceedings of the National Academy of Sciences, “the ‘origin story’ is missing many key details,” including a recent detailed evolutionary history of the virus, identity of its most recent ancestors and “surprisingly, the place, time, and mechanism of transmission of the first human infection.”
At first, it was suspected that Wuhan’s Huanan Seafood Wholesale Market was the location of the infection. The market was large, with 653 stalls, selling seafood but also fruits and vegetables, meat and live animals. Trade was carried out in chipmunks, foxes, raccoons, wild boar, giant salamanders, hedgehogs, sika deer, snakes, frogs, quail, bamboo rats, rabbits, crocodiles and badgers. The market was closed right after the outbreak began, and in the rush to disinfect, no samples were taken that might prove a virus connection. However, some environmental samples from the market contained virus matching those in patients who became ill. A study of 41 confirmed human cases from Wuhan showed that nearly 70 percent had a link to the market, but 30 percent did not, including three of the first four cases. The data are insufficient to settle whether the market was the contamination source, or whether it served to amplify the virus for human-to-human transmission, or both, or neither.
The questions will probably not be solved by physical samples. More likely, the answer will come from using genetic sequencing to chart how the virus moved from one animal species to another, and to humans.
The identity of the animal intermediary — if there is one — remains a puzzle. A coronavirus found in pangolins is close, genetically. Pangolins are used for traditional medicine in China. Some scientists have suggested in recent months widening the hunt for an intermediary to Southeast Asia, where other animal species may have been the host. The recent outbreak of the virus among mink in Denmark underscores the need to think broadly about zoonotic spillover.
Last December, when the outbreak began in Wuhan, China silenced eight doctors who were alarmed by the mysterious illness that was spreading fast. Then, during critical weeks in January, provincial and central governments kept the lid on public information as the virus spread. These early coverups were telltale symptoms of China’s authoritarian party-state in action. The secrecy has left legitimate questions about whether China will ever be open about the virus origin. President Trump hammered China over this during his reelection campaign, seeking to distract voters from his own failings.
Beyond the blame game, there are troubling questions in China that must be examined, including whether the coronavirus was inadvertently spread in an accident or spill from the Wuhan Institute of Virology, which had previously carried out research on bat coronaviruses. The institute collected samples from the Mojiang mine in Yunnan province in China in 2012 and 2013. Earlier in 2012, six miners at Mojiang exposed to bats and bat feces were hospitalized suffering from an illness similar to severe acute respiratory syndrome (SARS), and three died. The disease was similar if not identical to covid-19 and may have been a previously unrecognized parent virus. Conspiracy theorists have proposed more outlandish scenarios of a deliberately created pathogen, but they do not hold much water.
The Lancet Commission, formed by the British medical journal in July, has made a primary goal identifying the origins of covid-19 and averting future zoonotic pandemics. The journal declared “the evidence to date supports the view” that covid-19 “is a naturally occurring virus rather than the result of laboratory creation and release.” But the commission says, “The possibility of laboratory involvement in the origins of the pandemic should be examined with scientific rigor and thoroughness, and with open scientific collaboration.”
Meanwhile, the World Health Organization has launched a Global Study of the Origins of the virus. Early visits to China by the WHO did not explore virus origins, but instead focused on the urgent issues of viral transmission and pandemic response. Now, 10 Chinese scientists and 10 from elsewhere around the globe have begun to pursue where the virus came from. To be successful, they must have Beijing’s full cooperation. Nothing can be off limits, no possibilities ignored. It is in everyone’s interest, including China’s, to find the answers and prevent the next pandemic. If there is one lesson from this year, it is that no nation lives in isolation from a raging disease.
The WHO is a member organization that can appeal to China and persuade, but it lacks regulatory power to give orders. But it will be stronger with the United States rejoining, as President-elect Joe Biden has promised to do. Hopefully, too, the international scientists who are taking part will push hard for a rigorous and penetrating investigation, including the possibility of a laboratory accident.
“Preventing the next pandemic,”
Relman, “depends on understanding the origins of this one.”