Wuhan Institute of Virology
Since the publication on May 14th of the letter in Science calling for a new investigation into the origins of COVID-19, the lab leak theory has officially gone mainstream. Numerous articles testifying to its plausibility have been published, and President Biden ordered intelligence agencies to "redouble" their efforts to examine the virus's origin.

One of the best articles that's been published in recent weeks is a piece by Zeynep Tufekci in the New York Times. Although she doesn't come down in favour of one theory or the other (lab leak versus natural origin), she does lay out much of the circumstantial evidence for a lab leak. And it's not in short supply.

To begin with, you have the location of the first outbreak in Wuhan, China - home to the Wuhan Institute of Virology (as well as the Wuhan C.D.C.). It would be a remarkable coincidence, many have observed, if the pandemic just happened to get started in a city that hosts one of the world's major coronavirus research labs.

Some have countered that labs tend to be built where the viruses are. However, this simply isn't true in the case of the Wuhan Institute, as Tufekci points out. The lab has "been where it is since 1956... It was upgraded and began to focus on coronavirus research only after SARS." Even Dr. Shi (the "Bat Woman") has said she "never expected this kind of thing to happen in Wuhan".

Next, you have reports about the rather lax safety standards inside the Wuhan Institute. In 2016, for example, scientists ran experiments on a coronavirus capable of infecting human cells in a BSL-2 lab - a biosafety level that "has been compared with that of a dentist's office". And in 2017, a Chinese state-TV story about Dr. Shi's research "showed researchers handling bats or bat feces with their bare hands".

Then there is the fact that Dr. Shi, her colleagues and the Wuhan Institute, not to mention the Chinese authorities, have given misleading or incomplete accounts of key events, or have simply withheld important information. Aside from the location's first major outbreak, this is perhaps the strongest piece of evidence for a lab leak. If the virus's origin is zoonotic, why wouldn't you let other scientists look over your files?

On 3rd February, 2020, Dr. Shi and her colleagues "announced in Nature that they had found a virus in their database, RaTG13, whose genome sequence was 96.2% identical to SARS-CoV-2". Internet sleuths then "combed through genomic databases and found that RaTG13 was an exact match for a bat coronavirus called 4991", which had been implicated in an unexplained 2012 outbreak of pneumonia among miners in Yunnan. Neither the name change nor the previous outbreak were mentioned in Dr. Shi's paper.

That same group of internet sleuths also discovered that "a genomic database maintained by the Wuhan Institute of Virology, with information about thousands of bat samples... went offline in September 2019". (The official explanation is that it had been "subjected to hacking".)

On 10th December, Peter Daszak - organiser of the infamous Lancet letter, and a close collaborator of Dr. Shi's - dismissed suggestions that there were live bats inside the Wuhan Institute. In a now-deleted tweet he wrote, "We collect bat samples, send them to the lab. We RELEASE bats where we catch them!" However, contrary evidence has subsequently emerged.

As Tufekci notes, "The Chinese Academy of Sciences website has listed the Wuhan institute as having at least a dozen cages for bats, and in 2018 the institute applied for a patent for a bat cage. Dr. Shi has talked about monitoring antibodies in bats over time โ€” which would not be done in a cave."

Most suspicious of all, the Chinese authorities have straightforwardly "refused to share direct records from the lab". After the publication of the Science letter earlier this year, Dr. Shi told a reporter, "It's definitely not acceptable" for other experts to review her lab's records...

Another piece of the puzzle is the genetic sequence of the virus itself, including the presence of a so-called "furin cleavage site" on the virus's spike protein. This is something that Nicholas Wade discussed extensively in his essay back in May. Tufekci, though, isn't completely convinced. She notes, "aspects of the virus that have made some suspect it was bioengineered could also be evidence that the virus evolved naturally".

The fact that no intermediary host species has yet been identified arguably lends support to the lab leak theory. However, Tufekci raises the possibility that the virus passed straight from bats to humans. In that case, she says, "no intermediary animal is necessary, since it could have been any interaction with a bat - by a villager or a field researcher".

Finally, there's the frequency with which lab leaks have occurred in the past. Bayes theorem tell us that the probability of a hypothesis, given some evidence, is a function of the conditional probability of the evidence given the hypothesis, as well as the prior probability of the hypothesis.

If you take all of human history, the vast majority of pandemics have been caused by zoonotic spill-over - which would suggest the prior probability of a lab leak is quite low. However, sophisticated research labs have only been around for a few decades. (We can't pin the Plague of Justinian on inadequate safety protocols.)

"A better period of comparison", Tufekci notes, "is the time since the advent of molecular biology, when it became more likely for scientists to cause outbreaks." In fact, nearly every case of SARS since the original outbreak in 2002 has been due to lab leaks. There have been "six incidents in three countries, including twice in a single month from a lab in Beijing".

And such leaks are by no means confined to China. In 2007, foot-and-mouth disease "escaped from a drainage pipe leak at an English lab with the highest biosafety rating, BSL-4". I'm not aware of what percentage of epidemics are caused by lab leaks, as opposed to zoonotic spill-over, but it's probably larger than we've been led to believe.

Tufekci's article contains a lot of valuable insights, and is worth reading in full.