The origin of SARS-CoV-2, revisited
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If, as I have, you’ve been paying attention to these things for a number of years, you know that, whenever there is a major outbreak, epidemic, or pandemic of infectious disease, one conspiracy theory always—and I do mean always—arises. That conspiracy theory is that the causative microbe was developed in a laboratory and/or escaped a laboratory. HIV, H1N1, the original SARS, Ebola virus, every single one of them gave birth to such conspiracy theories. Unsurprisingly, given its global scope and death toll, so it was with SARS-CoV-2, the coronavirus that causes COVID-19.

Even as far back as February 2020, I noted that antivaxxer James Lyons-Weiler was falsely claiming that he had “broken the coronavirus code” and found nucleotide sequences in its genome indicating that it had come from a laboratory working on coronavirus vaccines, while Nobel Laureate turned crackpot Luc Montagnier also endorsed the “engineered virus” idea. For someone who is supposedly an expert in bioinformatics, his analysis was risibly bad. Then came the “plandemic” conspiracy theory, in which antivaxxer and disgraced scientist Judy Mikovits claimed that SARS-CoV-2 was not only engineered but intentionally released. As we discussed at the time, the nucleotide sequence of isolates of SARS-CoV-2 analyzed early in the pandemic showed no evidence of “engineering,” no telltale signs of having been synthesized or modified in a laboratory, and a more recent WHO report similarly concludes that the likelihood of a laboratory origin for the virus compared to the odds of a natural origin is very low.

The “lab leak” hypothesis is resurrected

The idea that SARS-CoV-2 originated in a laboratory has continued to bubble under the surface of discussions of the pandemic but wasn’t really a major discussion point for a number of months—that is, until recently. Last week, for example, President Biden instructed US intelligence agencies to “redouble” their efforts to “collect and analyze information that could bring us closer to a definitive conclusion” regarding the origin of SARS-CoV-2. Before that, journalist Nicholas Wade published an article in the Bulletin of the Atomic Scientists (who knows why it was published there instead of in a virology or molecular biology journal) arguing that the virus originated in so-called “gain-of-function” experiments and was accidentally released.

This followed a letter published in Science by a number of scientists advocating investigating the origins of the coronavirus and saying that we “must take hypotheses about both natural and laboratory spillovers seriously until we have sufficient data”. The authors were apparently unhappy with a joint Chinese and World Health Organization (WHO) investigation published in March that concluded that an animal origin for SARS-CoV-2 was far more likely than a lab leak, as Steve Novella discussed at the time. Personally, I was unhappy at how unconcerned at least one of the signatories was over how their letter had been used by conspiracy theorists as support for their ideas.

Then there was Fox News publicizing a fact-checking event earlier in May held by Politifacts that quoted Dr. Fauci thusly when asked about whether he was confident that SARS-CoV-2 arose naturally:

“No actually,” Fauci, director of the National Institute of Allergies and Infectious Diseases (NIAID) said, around 12 minutes into footage of the event, which was held earlier this month but overlooked by most media outlets. “I am not convinced about that, I think we should continue to investigate what went on in China until we continue to find out to the best of our ability what happened.”

“Certainly, the people who investigated it say it likely was the emergence from an animal reservoir that then infected individuals, but it could have been something else, and we need to find that out. So, you know, that’s the reason why I said I’m perfectly in favor of any investigation that looks into the origin of the virus,” he continued.

“Will you in front of this group categorically say that the COVID-19 virus could not have occurred by serial passage in a laboratory?” Sen. Rand Paul had asked Fauci during a Senate hearing last Tuesday.

Fauci did not explicitly rule out such a possibility: “I do not have any accounting of what the Chinese may have done, and I’m fully in favor of any further investigation of what went on in China,” he said. “However, I will repeat again, the NIH and NIAID categorically has not funded gain of function research to be conducted in the Wuhan Institute of Virology.”

Meanwhile, a week ago The Wall Street Journal published a story titled “Intelligence on Sick Staff at Wuhan Lab Fuels Debate on Covid-19 Origin” (there’s no evidence presented that they were sick with COVID-19), while the Washington Post published an analysis titled “Timeline: How the Wuhan lab-leak theory suddenly became credible“. To be honest, the latter story simply told me how the conspiracy theory that SARS-CoV-2 had a laboratory origin had arisen even earlier than I thought it had, all without providing any new data that would lead me to view the “lab leak” hypothesis for SARS-CoV-2 origin as more likely than a natural origin. Moreover, the first article basically doesn’t provide such evidence either, given that US intelligence officials are still not certain what the researchers actually had and Director of National Intelligence Avril Haines told Congress last month that “the intelligence community does not know exactly where, when, or how Covid-19 virus was transmitted initially”.

These developments led me to start to wonder if there was anything in the evidence base that had led most scientists to conclude that the most likely origin of SARS-CoV-2 was natural. Meanwhile, there seems to be a lot of Twitter activity of this sort:

We here at SBM are big fans of Bayes’ theorem, and as a big fan of Bayesian analysis, let me just say that Mr. Gordon demonstrates an epic misunderstanding of Bayes’ theorem. Personally, I like this response:

See? Bayes theorem can cut both ways with respect to estimating prior probabilities. As many have pointed out, when a virus makes the jump from animals to humans, it often takes years to figure out the origin. As Dan Samorodnitsky points out:

So, figuring out where this particular virus came from will be a challenge. It can take years, decades, or more to find the source of a virus. Ebola, for instance, was identified in 1976, has caused multiple epidemics, and we still don’t really know what animal it spilled over from. To confirm beyond a reasonable doubt the virus’s origins, we’d have to sample wild animals and sequence the viruses they carry to find a close genetic relative, an astronomical task, haystacks within haystacks. In the absence of a smoking gun, there’s still good research that points in one direction. Take the phylogenetic analysis in preprint this week that, once again, suggests bats as a reservoir for SARS-CoV-2, with pangolins or civets as possible intermediate steps.

In other words, it’s only been less than a year and a half since the virus was identified and sequenced. Just because scientists haven’t yet found “smoking gun” evidence for what specific animal coronavirus made the jump to humans as SARS-CoV-2 (and where) does not make a lab origin more likely. It just doesn’t. The argument is just plain silly, and the vacuous invocation of Bayes’ theorem makes my brain hurt.

Bad logic and math aside, I’ve noticed that the lab leak hypothesis has definitely—shall we say?—evolved during the last year. Given the utter lack of evidence in the nucleotide sequences of SARS-CoV-2 for an “engineered” origin, the “respectable” people now claiming that the coronavirus came from a lab hasten to deny that they think it was “engineered” or a “bioweapon.” Basically, there are now two main versions of the “lab leak” hypothesis:

  1. An engineered SARS coronavirus created at the Wuhan Institute of Virology through “gain of function” experiments somehow escaped and caused the pandemic.
  2. A natural SARS coronavirus stored and studied at the Wuhan Institute of Virology somehow escaped and caused the pandemic.

I can say with a high degree of confidence based on existing evidence that the first version is so implausible as to have drifted well into conspiracy theory territory. The second is the version that “reasonable” people consider plausible, but there is no good evidence for either version. In any event, given how much these hypotheses have been discussed in the news as though there were some new evidence that now makes the “lab leak” hypothesis more likely (spoiler alert: there isn’t) and assaulted me on social media, coming from conspiracy theorists and non-conspiracy theorists, I just had to look into this issue again. Let’s look at each version of the hypothesis. I’ll start with the much less plausible version and then examine the more plausible “variant” (if you’ll excuse the term).

Version 1: The virus was engineered and escaped.

An excellent entry point to the claim that SARS-CoV-2 was engineered and then somehow accidentally released into the wild, thus causing the COVID-19 pandemic, is a news story in The Daily Mail that I saw on Saturday, because it contains a couple of major themes that I’ve found used by many to argue for a lab origin for the virus, as well as the dubious scientific arguments. The story touts an as-yet unpublished paper by British Professor Angus Dalgleish and Norwegian scientist Dr. Birger Sørensen, described in the story as being “set to be published in the Quarterly Review of Biophysics Discovery.” In typical Daily Mail fashion, the headline is basically a conspiracy theory:
The Daily Mail headline

The rationale in the paper, judging from the excerpts and statements by Dalgleish and Sørensen, rests on an appeal to incredulity, specifically disbelief that SARS-CoV-2 could have arisen from a natural source. Such arguments are perhaps the most common arguments for a “lab leak” that I’ve seen, usually accompanied with incorrect reasons why such an origin is “impossible.” This article is no different in that general form.

When I first read the article, I had never heard of these scientists before and had no idea who they were; so I did a bit of Googling. Unfortunately, a lot of what came up first in the search results were links to the Daily Mail story and others reprinting the story, but I did learn that Dr. Dalgleish is an oncologist at St. George’s, University of London and ran for Parliament as a member of the UK Independence Party during the 2015 United Kingdom general election, finishing fourth. He is also a Fellow of the Academy of Medical Sciences, the Royal College of Physicians, the Royal College of Pathologists, and the Royal Australasian College of Physicians. He’s famous for having been the co-discoverer of the CD4 receptor as the major cellular receptor for HIV. Sørensen is the chair of a pharmaceutical company, Immunor, which developed a coronavirus vaccine candidate called Biovacc-19.

Normally I don’t blog about unpublished papers, preferring to wait for the whole paper to be published, but The Daily Mail not only published the abstract, but several tables and figures from the unpublished paper. That’s really, really unusual. Most journals would not be in the least bit pleased to see a newspaper do that. The story states that the article was “exclusively obtained by and slated for publication in the coming days.” Given the apparently enthusiastic participation of Dalgleish and Sørensen in interviews for the news story, it’s very hard to imagine how The Daily Mail might have gotten a copy of the paper from any other source besides the authors, although one of the three authors of the manuscript, Andres Susrud, posted an earlier version of the paper, which was not accepted:

There’s another huge red flag about this study and that’s the journal in which it was published, which was not in a molecular biology, biochemistry, or virology journal, but rather a biophysics journal. That’s not the first place I’d choose to publish an article of this sort, although QRB Discovery does describe itself as publishing “physical observations of relevance to biological systems, both experimental and theoretical, that may point towards an exciting direction, rather than the presentation of a traditional comprehensive study”, which might explain why Dalgleish and Sørensen decided to publish there instead of a more appropriate journal. Then there’s this excerpt of the story:

They said they tried to publish their findings but were rejected by major scientific journals which were at the time resolute that the virus jumped naturally from bats or other animals to humans.

So basically the authors went shopping until they found a journal that would accept their manuscript. There’s nothing inherently wrong with that. (Pretty much every scientist, myself included, has submitted a manuscript to a different journal after rejection by another journal, and many of us have had the unpleasant experience of having to submit to three or more journals before we could get an article published.) However, it does raise eyebrows when an article like this ends up in a journal that doesn’t seem appropriate for the material. Just look at the sorts of articles in the latest issue. They’re all pretty heavily weighted towards fairly hard core biophysical studies, rather than sequence analysis. Moreover, contrary to how it’s being described, as a “study,” in reality it’s more of a review article, with no new research published, at least as far as I can tell.

Now, let’s look at the Abstract and Conclusion sections, helpfully provided by the Daily Mail. Here’s the abstract:

Here’s the conclusion:
Dalgleish conclusion

I can’t help but note the rather strange wording of the abstract, namely the authors’ claim that their analysis is so compelling that it “reverses the burden of proof” for those who consider a laboratory origin of the virus highly unlikely and a natural origin much more so. Be that as it may, before I discuss the article and the figures, I have to point out yet another red flag that I discovered in the Daily Mail article. It was such a big one that it literally deserves a facepalm. Here’s the excerpt from the article:

One tell-tale sign of alleged manipulation the two men highlighted was a row of four amino acids they found on the SARS-Cov-2 spike.

In an exclusive interview with, Sørensen said the amino acids all have a positive charge, which cause the virus to tightly cling to the negatively charged parts of human cells like a magnet, and so become more infectious.

But because, like magnets, the positively charged amino acids repel each other, it is rare to find even three in a row in naturally occurring organisms, while four in a row is ‘extremely unlikely,’ the scientist said.

‘The laws of physics mean that you cannot have four positively charged amino acids in a row. The only way you can get this is if you artificially manufacture it,’ Dalgleish told

Their new paper says these features of SARS-Cov-2 are ‘unique fingerprints’ which are ‘indicative of purposive manipulation’, and that ‘the likelihood of it being the result of natural processes is very small.’

And here’s the facepalm, much deserved:

When Godzilla gives you the facepalm, you know the failure is monstrous.

There’s really only one word to describe this claim: Bullshit. I’m sorry if anyone is offended by mild profanity, but that really is the only word to describe the claim above, and scientists were quick to call it out as such on social media, with examples:

Personally, these are my two favorite responses:

Indeed. If it truly “violates the laws of physics” to have four positively charged amino acids all in a line next to each other in a protein, then it would be utterly impossible to engineer a nucleotide sequence that could encode such a protein, because translation would fail! Seriously, how could any journal allow a review article to make such a nonsensical argument? It turns out that four positively charged amino acids in a row is quite common, a motif found in thousands of different proteins. It’s tempting just to dismiss the whole thing based on such epic ignorance, but let’s dig in a little bit more because Dalgleish and Sørensen make another claim that is commonly made by those arguing for a laboratory origin.

The key claim made by Dalgleish and Sørensen is this:

Dalgleish and Sørensen claim that scientists working on Gain of Function projects took a natural coronavirus ‘backbone’ found in Chinese cave bats and spliced onto it a new ‘spike’, turning it into the deadly and highly transmissible SARS-Cov-2.

They base their argument on, in essence, an argument from ignorance, with a bit of conspiracy theory added. Yes, it is possible to create genetic sequences without, for instance, typical restriction enzyme sites of the sort that were frequently used to insert sequences into genomes. However, it isn’t nearly as easy as Dalgleish and Sørensen make it sound. Basically, to them these nefarious Chinese scientists were supposedly so clever that they not only did something that’s not at all trivial but did it without leaving behind any telltale signs in the sequence of genetic manipulation, other than the ones that only Dalgleish and Sørenson “discovered,” such as the six areas on the protein that basically every other scientist didn’t find suspicious. Then there’s the argument that a natural virus pandemic would be expected to “mutate gradually” to become more infectious but less pathogenic (i.e., deadly). Certainly, we’ve seen the former with the emergence of more transmissible variants of SARS-CoV-2 all over the world, but we haven’t seen the latter.

As virologist Angela Rasmussen pointed out:

Again, this argument is, quite simply, incorrect, and we wouldn’t necessarily expect SARS-CoV-2 to evolve to become less pathogenic and less deadly. Given that the infection fatality rate of SARS-CoV-2 is already well under 1% and a significant fraction of its infections are asymptomatic or only mildly symptomatic, there really isn’t likely to be that much selective pressure for mutations that make it less deadly, particularly when it’s still spreading so widely and easily.

As for the rest of the article, it’s a lot of handwaving and appeals to ignorance and conspiracy. Again, its two main points (that a four amino acid stretch of positive residues is so unusual) and that evolution would inevitably lead to a slow increase in transmissibility and decrease in pathogenicity, are clearly incorrect and cannot explain the origin of SARS-CoV-2. Indeed, there are now several papers that show how the virus likely evolved from previously existing coronaviruses and how it is continuing to evolve as is spreads. (Here is a good recent review article, and potential evolutionary pathways that could have led to SARS-CoV-2 were known as early as July 2020.)

Then there are the articles claiming to have slam-dunk scientific evidence that SARS-CoV-2 could not have arisen naturally. Chief among these (at least now) have been articles by Li-Meng Yan claiming that the published bat coronavirus RaTG13 genome, identified in a horseshoe bat (Rhinolophus affinis) and sharing 96% sequence homology with SARS-CoV-2, was, in essence, “fake” and generated as a cover-up to prop up the “natural origin theory.” (No, I’m not exaggerating; Yan even claims that any data questioning the “natural origin theory” is censored by scientific journals.) RaTG13 was found in archived bat specimens stored at the Wuhan Institute of Virology after having been collected in 2013. Others have demonstrated rather conclusively that they could generate the RaTG13 sequence from the raw sequence data submitted to public databases, concluding that the “published RaTG13 genome is supported by raw sequence data of good quality.” Uncoincidentally, Yan is also known for attacking scientists, such as Angela Rasmussen, who noted this in a commentary.

Another example of supposed “slam-dunk” evidence is the claim popularized in Wade’s article (mentioned above) that a site called a furin cleavage site is unique to SARS-CoV-2 among SARS beta coronaviruses. As I mentioned in last week’s article, the spike protein in SARS-CoV-2 consists of two subunits. Between those two subunits, S1 and S2, sits a site where a human protein called furin cleaves the protein, to produce the two functional subunits. Wade claimed:

Viruses have all kinds of clever tricks, so why does the furin cleavage site stand out? Because of all known SARS-related beta-coronaviruses, only SARS2 possesses a furin cleavage site. All the other viruses have their S2 unit cleaved at a different site and by a different mechanism.

How then did SARS2 acquire its furin cleavage site? Either the site evolved naturally, or it was inserted by researchers at the S1/S2 junction in a gain-of-function experiment.

Basically, Wade’s argument seems to be that because a furin cleavage site of this sort hasn’t been seen in SARS-related beta coronaviruses before it must have been engineered. The problem is that such furin cleavage sites are common in a wide variety of viruses, including coronaviruses, and that scientists already had identified plausible mechanisms by which it could have ended up where it did in SARS-CoV2 last year:

I could go on and on and on with this stuff, but basically all the claims that SARS-CoV-2 couldn’t have arisen naturally don’t show anything of the sort and often betray ignorance of the actual molecular biology of the virus and even greater ignorance of how animal models work. One other claim that keeps popping up is that SARS-CoV-2 appeared “perfectly adapted” to humans as a host. (Wade alludes to this.) This study suggests a pathway by which natural selection in bats could have created a more “generalist” virus, rather than specifically adapted to humans. In other words, SARS-CoV-2 isn’t “perfectly adapted to humans,” just well adapted enough to infect them efficiently.

A more general take on the “lab leak” of an “engineered” virus

Perhaps the most basic refutation to the “engineered” virus narrative is a simple one. As good as virologists are, they don’t know a priori the features that make a virus more likely to infect and harm humans. As Ethan Siegel at Forbes put it:

The science of what can be done in virology, with modern techniques, is quite impressive. But what the conspiracy attests must have happened reaches far beyond the capabilities of even the most advanced research teams in the world.

The first red flag that should leap out at you, but perhaps only if you have some knowledge of virology to begin with, is the very idea that you could “know” what certain mutations would do — i.e., that you’d know what you’d create and what effect it would have on humans — without extensive testing in humans themselves.


While we do have the ability to manipulate the genomes of viruses, or any other organism, for that matter, what we don’t have the ability to do is to know how that will translate into effects of the virus in human (or any living) subjects.

That’s not entirely true. It’s not that we can’t always predict what specific mutations might do. We now know enough about protein structure and function to make educated guesses about how changing an amino acid to another is likely to affect protein structure in some instances. Siegel is correct, though, that we do not have the sort of fine-tuned ability to make precise predictions.

As University of North Carolina virologist Ralph Baric put it:

Baric said that sars-CoV-2 was different enough from known viruses that to retrofit it from an ancestral strain would have required a truly unprecedented feat of genetic reëngineering. “And of course you don’t know what you’re engineering, because sars-CoV-2 would not have existed,” Baric said.

The engineering of a virus that didn’t exist yet (without knowledge of how to make it more transmissible between humans) seems very unlikely

Version 2: Lab leak of a “natural” SARS beta coronavirus

The second version of the “lab leak” hypothesis is basically the claim that SARS-CoV-2 escaped from the Wuhan Institute of Virology but wasn’t engineered. Rather, according to this version, it was a bat coronavirus that had been collected for study and stored at the Institute. The closest thing to “new evidence” that I’ve seen cited in favor of this has been reporting from The Wall Street Journal last week, for example, The Wuhan Lab Leak Question: A Disused Chinese Mine Takes Center Stage. First, there’s the background:

On the outskirts of a village deep in the mountains of southwest China, a lone surveillance camera peers down toward a disused copper mine smothered in dense bamboo. As night approaches, bats swoop overhead.

This is the subterranean home of the closest known virus on Earth to the one that causes Covid-19. It is also now a touchpoint for escalating calls for a more thorough probe into whether the pandemic could have stemmed from a Chinese laboratory.

In April 2012, six miners here fell sick with a mysterious illness after entering the mine to clear bat guano. Three of them died.

Chinese scientists from the Wuhan Institute of Virology were called in to investigate and, after taking samples from bats in the mine, identified several new coronaviruses.

Now, unanswered questions about the miners’ illness, the viruses found at the site and the research done with them have elevated into the mainstream an idea once dismissed as a conspiracy theory: that SARS-CoV-2, the virus that causes Covid-19, might have leaked from a lab in Wuhan, the city where the first cases were found in December 2019.

All this story tells us is that bats harbor all sorts of interesting and potentially dangerous coronaviruses. (One notes, however, that this is how the RaTG13 sequence was initially collected, as I mentioned above.) Then there was another WSJ article reporting:

Three researchers from China’s Wuhan Institute of Virology became sick enough in November 2019 that they sought hospital care, according to a previously undisclosed U.S. intelligence report that could add weight to growing calls for a fuller probe of whether the Covid-19 virus may have escaped from the laboratory.

The details of the reporting go beyond a State Department fact sheet, issued during the final days of the Trump administration, which said that several researchers at the lab, a center for the study of coronaviruses and other pathogens, became sick in autumn 2019 “with symptoms consistent with both Covid-19 and common seasonal illness.”

This is some really thin gruel. It isn’t even known if these researchers actually had what is now called COVID-19. They could have had influenza or another virus.

Both forms of the lab leak hypothesis share one element, namely constant finger pointing at the Chinese for being less than enthusiastic and cooperative about letting investigators into the Wuhan Institute of Virology to try to determine if a lab leak happened. This is, of course, not surprising and not in and of itself evidence for a lab leak. China is an authoritarian regime, and such regimes tend to be secretive. However, for an authoritarian regime, China appears to have actually cooperated more than you might have imagined, at least based on this interview with some of the actual scientists who went to Wuhan to investigate for the WHO. Or at least you can say that the Chinese weren’t nearly as obstructionist as claimed:

Think of it this way. What country would welcome investigators with open arms into one of their major research institutions to look for evidence that its scientists had screwed up and caused a major disaster? Even if a government were confident that no such error had occurred, it might not be too thrilled with such an investigation, particularly when it’s coupled with what can only be called accusations of wrongdoing and being instigated by people hostile to you. That the Chinese are testy and unenthusiastic about cooperating is not a strong argument in favor of a lab leak. Sure, it could be a sign of a coverup, but it could also just be a normal reaction to accusations.

Bottom line: There is no new evidence that we haven’t known about for a long time that would lead to the reprioritizing of the two hypotheses to lead the lab leak hypothesis to become much more plausible.

Two hypotheses ≠ equally likely hypotheses

From the very beginning, the general scientific hypothesis has been that, while it is possible that SARS-CoV-2 escaped from a lab, it’s far more likely that it had a natural origin. As Samorodnitsky put it:

Though there is no direct evidence for either idea, the natural origins hypothesis has scientific precedence. The coronavirus family of viruses, that SARS-CoV-2 is a part of, have spilled over into humans (SARS and MERS) and caused pandemics. Natural origin also takes into consideration natural phenomena that happen all the time in wild viruses — they reproduce rapidly, mutate frequently, acquire bits of DNA like a boat collecting barnacles, and change behavior, particularly when they shift from one host to another. These processes happen in all viruses.

But, the permanent uncertainty of SARS-CoV-2’s origins has made other explanations, no matter how complex, attractive.

I’m going to quote this paragraph too, because I wish I had thought of a way this good of saying this:

If the question is “are both hypotheses possible?” the answer is yes. Both are possible. If the question is “are they equally likely?” the answer is absolutely not. One hypothesis requires a colossal cover-up and the silent, unswerving, leak-proof compliance of a vast network of scientists, civilians, and government officials for over a year. The other requires only for biology to behave as it always has, for a family of viruses that have done this before to do it again. The zoonotic spillover hypothesis is simple and explains everything. It’s scientific malpractice to pretend that one idea is equally as meritorious as the other. The lab-leak hypothesis is a scientific deus ex machina, a narrative shortcut that points a finger at a specific set of bad actors. I would be embarrassed to stand up in front of a room of scientists, lay out both hypotheses, and then pretend that one isn’t clearly, obviously better than the other.

Precisely. The natural origin hypothesis tends to the default for any new disease that arises for the simple reason that it is by far the most likely to be the correct explanation. It’s very common for viruses to mutate and evolve in animals and then jump over to humans and pandemics have been caused this way before. Again, the likelihood of the two hypotheses is nowhere near close to equal, and the plausibility of the hypothesis of a lab leak of an engineered virus is so low that it makes that version of the “lab leak” hypothesis even less likely than a leak of a natural virus. Even prominent signatories of the Science letter don’t actually believe that SARS-CoV-2 escaped from a lab:

On Tuesday evening, I spoke by video call with Ralph Baric, the U.N.C. virologist whose work had fallen under Rand Paul’s suspicious gaze. Baric had also signed Relman’s letter in Science, but he told me that his concerns had been with the W.H.O.’s failure to conduct a thorough, transparent review of biosafety measures at the Wuhan Institute of Virology. “I really believe that the genetic sequence for sars-CoV-2 really points to a natural-origin event from wildlife,” he said. Baric was sturdy-looking, with a paintbrush mustache and slightly melancholy eyes. The suggestion that it would have taken some Chinese science experiments to get the virus from bats in Yunnan to human beings in Wuhan seemed to leave him slightly affronted, on behalf of the natural world. However large the Wuhan Institute’s library of bat viruses, he said, the repository of viruses out in nature exceeded it by “many orders of magnitude.”

So why has the lab leak hypothesis seemingly risen from its grave and shambled off to social media and the news? One reason is politics. However another reason is, quite simply, likely to be pandemic fatigue. Knowledge is power, and it is also comforting. If we were to know the origin of this pandemic, the thinking goes, then we would better know how to prevent future pandemics. Maybe so, but here’s the thing. Even if the lab leak hypothesis is true, and SARS-CoV-2 escaped from a lab in China, it would make absolutely zero difference in how we need to deal with the pandemic now.

As Samorodnitsky put it:

The most bothersome thing about all this is that it does not particularly matter where SARS-CoV-2 came from. Making a scapegoat out of China doesn’t do anything about the political and economic systems that allowed millions to die, especially in wealthy nations like the US that could easily afford muscular public health responses.


Creating a webbed story of cover-ups and conspiracy allows us to ignore how in many ways all humans caused the COVID-19 catastrophe. What if it wasn’t one bad Chinese government’s fault, but the whole world’s fault for destroying habitats, mining too deeply, and creating the perfect conditions for natural viral spillovers?

What if, indeed. Early in the pandemic, knowing the source of an outbreak can certainly guide efforts to contain it, including contact tracing, shutting down specific sites of the outbreak, and quarantine anyone exposed to the virus. That time for COVID-19 came and went a long time ago. Even in the unlikely event that the lab leak hypothesis is confirmed, it won’t help us deal with the pandemic now. I’d even question just how much this knowledge would help us prevent future pandemics, except briefly, given that it is human nature to forget and any safety measures implemented would likely fade in intensity with time.

Unfortunately, now the lab leak hypothesis has become, in essence, a conspiracy theory. It is weaponized uncertainty designed to frighten people for political purposes.

ADDENDUM: This Week in Virology has done another video podcast on the issue of a “lab leak.”

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