IF YOU TAKE THEIR ILLIUSIONS WHAT DOES THE rIGHT HAVE LEFT?:

I started to take an interest in this debate after Quillette published Philippe Lemoine's critical examination of the lab-leak hypothesis in late 2020. I began following advocates on both sides of the argument on social media, I read Chan and Ridley's book, as well as papers, preprints, blogs, and articles, and I kept an eye on (but did not participate in) the endless discussion threads devoted to the topic proliferating across social media. And by the time I reached saturation point, I'd concluded that, popularity notwithstanding, the lab-leak hypothesis simply doesn't add up.

In what follows I want to explain why. I am neither a scientist nor a science writer, so this will not be a technical essay. Nor will I be offering any original research. This will be a critical analysis of the debate along with some concluding thoughts about how and why the discourse on this topic has diverged so sharply from the available evidence. Although gaps remain in the natural hypothesis of COVID-19's origins, the lab-leak alternative is poorly supported and internally incoherent. The debate only continues because popular consensus is not yet ready to accept this.

II. The Wuhan Labs

The most intuitively compelling argument for a lab accident relates to the proximity of the lab to the outbreak, and it goes something like this:

A coronavirus pandemic began in Wuhan.

Wuhan has multiple virology laboratories studying coronaviruses.

Therefore, the pandemic was almost certainly caused by a laboratory accident.

This isn't really evidence--it's a claim about how we ought to evaluate our priors in the absence of any other information. On the eve of the pandemic, there were two possible routes by which a respiratory virus that originated in bats in rural southern China might reach the central metropolis of Wuhan. It might be sampled during fieldwork by scientists and transported back to a Wuhan lab for research purposes. Alternatively, the virus might be carried into one or more of the city's four wet markets by the illegal wildlife trade. A probability assessment that ignores the presence of wet markets makes no more sense than one that ignores the presence of virology labs. And before any pandemic data became available, there were already good reasons to prefer the market hypothesis.

First, virology labs are a lot safer than wet markets because lab researchers are trained to handle dangerous pathogens and it is in their interests to adhere to strict biosafety protocols governing the research and storage of viruses. That is not to say that accidents never happen. They do. But a priori, a spillover is much more likely to result from the unregulated trade in known vectors of disease than from an accident in a tightly controlled environment. As Lemoine noted, very few people work in virology labs while millions of rural Chinese (not to mention many millions more susceptible animal hosts) are potentially exposed to coronaviruses every year. It is also worth bearing in mind that while the WIV has one of the world's largest collections of coronaviruses, those samples represent a minute fraction of those circulating in the wild.

Second, a natural (or "zoonotic") spillover is supported by copious historical precedence as well as recent experience. 2009 H1N1, Ebola, HIV, SARS, and MERS all spilled from animals into humans without ever seeing the inside of a virology lab, as did countless pathogens before them. Like SARS-CoV-2, the SARS outbreak in 2002-03 occurred hundreds of miles from the bat colonies in which the virus originated. It is thought to have spilled from bats into an intermediate host--probably palm civets--which were then transported to wildlife markets in China's Guangdong Province. There, they infected the traders and customers, who in turn infected their families and colleagues causing an epidemic that eventually spread to 30 countries killing at least 774 people and sickening thousands more.

Before the SARS pandemic, most opposition to China's wildlife trade was focussed on animal welfare. The discovery that it could also pose a mortal threat to public health threw a multibillion-dollar industry into crisis. On April 29th, 2003, China's State Forestry Bureau announced a national ban on wildlife trading and consumption, and in the ensuing crackdown, hundreds of thousands of wild animals were confiscated and destroyed, and thousands of breeders, transporters, and vendors found their livelihoods plunged into uncertainty.

The preventative measures would not last, however, and in a paper for the Environmental Policy and Law journal, published on December 21st, 2021, Peter Li argued that the ban never stood a chance:

The [Chinese Communist] Party's set policy of elevating the national economy from the old and resource-exploitative model of production to a sustainable development model offered the wildlife industry a good opportunity to expand and intensify. The Party's policy guidelines also gave the national and local forestry bureaus a golden opportunity to seek a budgetary expansion in anticipation of greater regulatory responsibilities. The SARS pandemic and the trade ban were an unexpected threat to both the industry and the administrative agencies.

Sustained lobbying by the industry found a sympathetic ear in the CCP, which believed the trade in wildlife to be an engine of rural economic regeneration, and in August 2003, the national ban on wildlife trade and consumption was rescinded. Trading resumed, and when Eddie Holmes visited the Huanan market in late 2014, he found caged wild animals being illegally sold for food, including coronavirus-susceptible raccoon dogs. "By the end of 2017," Li reported, "the wildlife industry had become a gigantic business operation with an annual revenue of 520 billion yuan (US $77 billion)."

When the Wuhan Municipal Health Commission announced the discovery of a cluster of novel pneumonia on December 31st, 2019, an epidemiological link to the city's Huanan Seafood Wholesale Market had already been established. No epidemiological link has since been found to any other location in the city. Chinese authorities revealed that a novel coronavirus was the causative agent of the new disease on January 7th, and the SARS-CoV-2 genomic sequence was released three days later. When human-to-human transmission was confirmed by China's Health Ministry on January 20th, it opened up the possibility that the Huanan market was merely the site of a superspreader event, not a spillover.

But this hypothesis began to look more improbable as we learned about the manner in which SARS-CoV-2 spread. Like other coronaviruses, community transmission of wild-type SARS-CoV-2 occurred mostly in clusters, with roughly 10 percent of cases responsible for 80 percent of infections. Adam J. Kurchaski, an associate professor at the London School of Hygiene and Tropical Medicine, told Science in May 2020 that "most chains of infection die out by themselves and SARS-CoV-2 needs to be introduced undetected into a new country at least four times to have an even chance of establishing itself. ... If the Chinese epidemic was a big fire that sent sparks flying around the world, most of the sparks simply fizzled out."

It is therefore unlikely (though not impossible) that a single market visitor would have infected enough people to ignite an epidemic. In Wuhan's wet markets, on the other hand, distressed wild animals were trapped in cramped and unsanitary conditions in an enclosed environment through which thousands of people of all ages and susceptibilities passed each day. If any of those animals were infected with SARS-CoV-2, the stalls selling and butchering them would have turned the market into a focus of infection, seeding cases in the surrounding neighbourhood just as the Broad Street water-pump seeded a cluster of cholera cases during the 1854 epidemic in London. In a densely populated city and transportation hub like Wuhan, such a focus of infection would create the ideal conditions for a pandemic.

In June 2021, Xiao and colleagues published the results of a survey of Wuhan's live-animal markets, which one of the authors had conducted between May 2017 and November 2019. Their findings confirmed the presence of susceptible wildlife at the Huanan market and the dangerous conditions in which they were kept for sale and slaughter. "Across all 17 shops," the authors wrote, "vendors reported total sales of 36,295 individuals, belonging to 38 terrestrial wild animal species, averaging 1170.81 individuals per month."

Almost all animals were sold alive, caged, stacked and in poor condition. Most stores offered butchering services, done on site, with considerable implications for food hygiene and animal welfare. Approximately 30% of individuals from 6 mammal species inspected had suffered wounds from gunshots or traps, implying illegal wild harvesting.

This was plainly a disaster waiting to reoccur, if not in Wuhan in 2019, then at another wet market in another Chinese city, irrespective of whether or not that city happened to host one or more virology laboratories. Widespread suspicion that the Wuhan epidemic originated in one of the city's wet markets was not an arbitrary bit of misdirection, it was simply the most logical inference from the information then available. The emergence in 2019 of a novel coronavirus in a Chinese city with four wet markets trading susceptible wild animals most obviously suggested a recurrence of 2002-03. Even the Chinese CDC believed this to be the case.

It has now been conclusively established that the virus was in the market in December 2019. Environmental swabs collected there by the Chinese CDC between January 1st and March 2nd, 2020, yielded 40 positive results, from which three live samples were isolated. By the time the CDC arrived, disinfection teams dispatched by the Wuhan Municipal Health Commission in the early hours of January 31st had already begun the clean-up operation. The Wall Street Journal subsequently reported that some of the solution used was so powerful that it corroded the disinfection equipment. That any positive samples were recovered at all indicates that the market was awash with virus before the clean-up operation began.

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