|The W.H.O. report stated that some wild-meat suppliers to Wuhan were located in south China, where horseshoe bats that host sars-like coronaviruses primarily reside. Perhaps that is where the virus crossed from bats to animals, and those sickened animals were brought to Wuhan, where they were sold in Huanan and the city’s three other known live-animal markets. “The big missed opportunity, clearly,” Andersen said, “was testing potential reservoirs—intermediate hosts at these markets, not just at Huanan market but across Wuhan, as well as the farther-flung farms where these animals came from, which, to my knowledge, was officially not done.”|
The Chinese government shuttered and sanitized the Huanan market on January 1, 2020, essentially destroying a crime scene. China’s officials told W.H.O. investigators that no live mammals were sold there—a position they still maintain. But a virologist at Hubei University of Traditional Chinese Medicine had been, he wrote, “serendipitously” conducting monthly surveys to identify the source of a severe tick-borne disease. In June, he published a study containing documentary evidence that, in the two years prior to the emergence of sars-CoV-2, nearly fifty thousand live animals representing thirty-eight wild species—many of which are now known to be susceptible to sars-CoV-2—were sold and butchered in Wuhan markets, including Huanan.
In February, 2020, China banned the trade and consumption of live wild animals. Tens of thousands of farms were shut down throughout the country. A farmer in Yunnan said that the government had bought and killed his mischief of bamboo rats. Chinese officials have not shared the extent to which they tested the farm animals and workers before the mass slaughter. This makes “any evidence of early coronavirus spillover increasingly difficult to find,” the W.H.O. mission noted in its report. Chinese officials told the W.H.O. that their scientists did test more than eighty thousand livestock, poultry, and wild-animal samples, across thirty-one provinces, collected both before and after the outbreak, but found no evidence of sars-CoV-2.
The world’s most trafficked animal, the pangolin, was initially thought to be a likely contender in the intermediate-animal search, not because they were sold at Huanan market but because, in early 2020, tissue samples from a group of pangolins—confiscated from smugglers at China’s southern border—tested positive for a coronavirus. There are coronaviruses particular to all sorts of animals, but this one was weird. Part of its spike protein, the receptor binding domain, could bind more tightly to human ace2 than sars-CoV-2’s. Back in February, 2020, Andersen had been suspicious of sars-CoV-2’s ace2 binding strength. The pangolin-coronavirus discovery helped change his mind. If the pangolin had naturally evolved a coronavirus primed for binding to ace2, then sars-CoV-2 could have naturally evolved such a feature as well. (The rest of the pangolin coronavirus was too distinct from sars-CoV-2 to be its source.)
Since then, close relatives of sars-CoV-2 have been identified in China, Thailand, Cambodia, and Japan. But the most significant finding supporting a natural origin was announced in September. Scientists in Laos—just south of the border from Yunnan—found a horseshoe-bat coronavirus that is genetically closer to sars-CoV-2 than the virus from the Tongguan mine. It might have split from a common ancestor with sars-CoV-2 sometime in the last decade or so. Alarmingly, their spikes are identical and bind with equal efficiency to human ace2 receptors. The discovery “completely blows away many of the main lab-leak arguments about Yunnan being special,” Andersen said. “These types of viruses are much more widespread than we initially realized.”
DARPA later proposed a project to create a similar coronavirus that would infect various species of animals including humans.