Alina Chan and Matt Ridley’s Viral is a book about the investigation into the origins of the COVID-19 pandemic. In case you haven’t been following, there’s been a shift in the scientific consensus on this topic. For about the first year of the pandemic, it was widely accepted that SARS-CoV-2, the virus behind COVID-19, had a natural origin, meaning that it first spread to humans naturally from an animal (also called a zoonotic origin). Any suggestion that it could have come from a lab was dismissed as a conspiracy theory. Then, sometime around spring 2021 something changed. Well-known, respected scientists began to voice the opinion that SARS-CoV-2 might have come from a lab, or that it’s at least a plausible hypothesis that deserves an investigation. The scientific consensus abruptly shifted from “definitely natural origin” to “both natural origin and lab origin are viable hypotheses that should be investigated.”
Viral is a deep dive into this issue from all angles, covering the basics of virology, the history and epidemiology of the COVID-19 pandemic, the response of scientific and governmental institutions, and various pieces of evidence for both hypotheses. It doesn’t contain any new, bombshell revelations, but it’s a neat, accessible summary of the scattered bits of information that have been uncovered since the start of the pandemic. In this review I’ll try to distill some of the most important information and discuss my own interpretation of it.
I enjoyed the book and recommend it to anyone interested in the topic. However, many of the authors’ points (especially on technical issues) have counterpoints from other scientists who lean more heavily towards the natural origins hypothesis. So I think it’s best to include the book as part of a “package-deal” recommendation, rather than presenting it as a perfectly objective source. The last section of this review will include some more recommended sources to check out, including writing from advocates of the natural origins hypothesis with counterpoints to claims made in the book. I’ll also link one here in case you don’t make it that far.
In my view, the book actually deals with two separate topics. The first is the object-level question – where did COVID come from? The second is the meta-level question – what can we say about the ability and willingness of different institutions to answer the question of the pandemic’s origins?
These questions need to be decoupled if we’re going to answer them properly. For example, a lot of people have noticed the incompetence and untrustworthiness of various institutions during the pandemic, and concluded in a knee-jerk reaction that this confirms the lab leak hypothesis… but this is wrong. At the same time, if it turns out that COVID had a natural, non-lab origin, that would not absolve the public health officials, scientists, journalists, and tech companies who prematurely dismissed the lab leak hypothesis for unscientific reasons.
A misconception about the book is that Chan and Ridley are 100% convinced that SARS-CoV-2 originated in a lab. This is wrong. The authors’ position is that the lab origin and natural origins hypotheses are both viable, and that neither one can be ruled out based on current evidence. The thesis of the book is not that SARS-CoV-2 definitely originated in a lab, but that the origin of the virus is unknown and warrants a thorough, open investigation.
Due to their own uncertainty about the origin of SARS-CoV-2, Chan and Ridley actually do a pretty good job of laying out the case for natural origins. It’s not convincing at all to hear “SARS-CoV-2 definitely had a natural origin, and anything else is just a conspiracy theory”. On the other hand, when you’re trying to weigh two legitimate, competing hypotheses, it becomes necessary to seriously consider the evidence for each one, and Chan and Ridley spend much of the book considering the evidence of natural origins.
The main case for the natural origins hypothesis is that it should be our default belief, in the absence of convincing evidence otherwise. The vast majority of disease outbreaks like this, including previous coronavirus outbreaks SARS (2003) and MERS (2012), came from nature, not from a lab. So, before examining the evidence, we should begin with a strong prior in favor of natural origins.
Also, the Chinese government and scientists deny lab origins of the virus. In the context of an authoritarian system this may count for very little, but it’s still some nonzero evidence in favor of natural origins. To say there was a lab origin, we would have to postulate that scientific institutions in China are lying and successfully engaged in a coverup, for which there have been no credible whistleblowers. Again, this may be entirely possible, but it still adds to the burden of proof that must be overcome by evidence for the lab leak hypothesis.
However, what’s still missing is any direct evidence for an animal source of SARS-CoV-2. Chan and Ridley note that during the SARS (2003) and MERS (2012) coronavirus outbreaks, the animal sources were discovered relatively quickly. But with COVID-19, now more than 2 years into the pandemic, an animal source still has not been identified, despite the fact that we now have access to better investigative tools, like faster and cheaper genome sequencing compared to the SARS and MERS investigations.
The authors steel-man one possible explanation for this lack of direct evidence that would be consistent with a zoonotic origin: illegal smuggling. They explain that if the animal source had been an illegally smuggled animal, the smugglers may have engaged in a coverup and tried to hide their tracks. Chan and Ridley spend a section of the book describing the illegal wildlife trade in China – a reminder that even if the pandemic had what we’re calling a “natural origin,” it was likely still a self-inflicted wound for humanity, and policy changes may still be needed to prevent it from happening again.
As a non-fiction book on current events, an unavoidable weakness of Viral is that it does not include recent developments that have come out after the book’s publication. At least one of these developments is important enough for me to mention in this review. In February 2022, three scientific pre-prints [1, 2, 3] were released, related to the spread of SARS-CoV-2 in the Huanan seafood market in the early stage of the pandemic. The Huanan seafood market, located in Wuhan, is thought by natural origins proponents to have been the source of the first zoonotic spillover (or possibly, two separate spillovers) into humans. Advocates of this hypothesis have taken these pre-prints as further confirmation of a zoonotic origin in the market. However, proponents of the lab leak hypothesis have pointed out that they never denied that an early superspreader event occurred in the market – they just think the virus was brought there by an infected human, and spread to others in the crowded and enclosed space. They point to the fact that all of the market animals that were tested for COVID came up negative. Fence-sitters, like Chan, say that the pre-print findings appear to be consistent with both hypotheses.
There are also technical points and counterpoints about these studies being debated. For example, one of the studies attempts to use geospatial analysis to show that locations of early COVID cases seems to cluster around the market. A possible rebuttal to this point is that it might be based on ascertainment bias – at the start of the pandemic, authorities suspected the market as a source of the outbreak and specifically looked for patients who’d recently been at the market, so it’s not surprising to see early cases cluster around the market if market exposure was part of the criteria for being diagnosed with COVID.
A lot of these technical points are over my head, so I encourage you to read the pre-prints (as well as the critiques of them) yourself. Here are some more sources to check out about these recent pre-prints and the debate around them [1, 2, 3].
When I first heard the idea of a lab origin of SARS-CoV-2 at the beginning of the pandemic, part of the reason I dismissed it was because the idea of a pathogen escaping from a lab really did seem like a conspiracy theory, or the plot of some sci-fi movie. One of the things that made me reconsider this position was learning how many lab leaks have occurred in the past. Chan and Ridley spend a chapter in the book reviewing some of these incidents. For example:
These are only a few of many examples. According to the US Federal Select Agent Program, which oversees the possession and handling of dangerous biological agents and toxins, there were 219 accidental releases of these “select agents” in 2019. So, while accidental lab leaks are uncommon, they’re not unheard of. When it comes to the COVID-19 pandemic, it still makes sense to have a strong prior in favor of the natural origins hypothesis, but the idea that a pathogen can be accidentally released from a lab isn’t some wild, ridiculous idea like believing in alien abductions or Bigfoot or something.
There’s a famous psychology experiment[13] in which participants were told to wait in a room, and their reactions were recorded as the room gradually filled with smoke. In some cases, participants waited alone, while in other cases they waited with a group of people who, unbeknownst to the participant, were actors who had been instructed to ignore the smoke. Of the participants who waited alone, 75% reported the smoke. However, of the participants who waited with the group, only 10% reported the smoke.
Photograph of the famous Latané and Darley experiment, cerca 1968.
So, what could those participants have been thinking? Maybe something like: Hmm, why’s the room filling up with smoke? Is this a problem? *looks around the room* Well nobody else seems to care, so I guess not.
Looking back at the early stages of the COVID-19 pandemic, I think maybe this is why so many of us didn’t think twice about the location of the initial outbreak. Hmm, is it kinda suspicious that this virus broke out near a major virology institute that works on bat coronaviruses? Should we maybe look into that? *looks around* Well nobody else seems to think so, so I guess not.
I can’t speak for everyone else, but this was at least my mindset. I had vaguely heard something about how there was a virology research institute close to where the pandemic broke out, and that some conspiracy theorists were claiming it was the source of the virus. I looked around and noticed that nobody was really taking this idea seriously, so I figured I didn’t need to take it seriously either.
Also, I was thinking something like: Eh, probably every major city has labs and research institutes doing this kind of research. And I’ll bet they purposely built the virology institute close to where these viruses occur in nature, to give them easy access for sampling.
Well, it turns out both of these things are wrong.
The type of research conducted at the Wuhan Institute of Virology (WIV) is pretty rare and specialized. It includes things like creation of chimeric coronaviruses [1, 2], infecting humanized mice with bat coronaviruses, and other types of gain of function research, which Chan and Ridley devote a chapter to.
The WIV is one of only a few institutions in the world doing this type of research. It’s not the case, as I had assumed, that every major university has a couple labs doing similar work.
So it does seem like a pretty remarkable coincidence that the outbreak happened in Wuhan. But maybe they purposely built the Wuhan Institute of Virology close to where these viruses are found in nature? Well, this also turns out to be wrong. The areas where viruses most similar to SARS-CoV-2 are found in nature are Yunnan province and Laos, which are more than a thousand kilometers away from Wuhan. The authors put this distance in perspective by noting that it’s more than the distance between Orlando and NYC.
Image source: https://www.bloomberg.com/news/features/2020-12-30/china-is-making-it-harder-to-solve-the-mystery-of-how-covid-began
If SARS-CoV-2 originated in an animal somewhere around the Yunnan / Laos area, how did it make it all the way to Wuhan without leaving a trail along the way?
Although I enjoyed the book, I do have one pretty major criticism. The authors repeatedly make the claim that a virus called RaTG13, which was being studied at the WIV before the pandemic, is the closest known genetic match to SARS-CoV-2. But this claim is outdated and no longer correct. In September 2021 researchers identified a virus called BANAL-52 in Laos that’s a 96.8% match to SARS-CoV-2, closer than RaTG13’s 96.2% match. (Important note: a 96.8% match is still a long way off in genomic space, and does not imply that this is the same virus as SARS-CoV-2, or even necessarily a progenitor.)
At first I thought maybe the authors didn’t mention BANAL-52 because it was discovered after the book was published, but this isn’t the case – Viral was published November 16, 2021, nearly two months after the discovery of BANAL-52 was published. Although I’m writing an overall-positive review here, I don’t want to go easy on the book where serious criticism is warranted. It’s completely unacceptable that BANAL-52 wasn’t mentioned. Even if it would have been inconvenient from a publishing standpoint, the authors should have rewritten the RaTG13 chapter, or at least included an addendum about the discovery of BANAL-52.
With that being said, I think the story of RaTG13 is still interesting and important, so I’ll give a quick summary here.
At the start of the pandemic in 2020, SARS-CoV-2 was quickly sequenced, and the full genome sequence was published by Dr. Shi Zhengli’s team at the WIV. In this paper, they also briefly mentioned that the genome was a 96.2% match with another bat coronavirus called RaTG13 – the closest known match at the time. Oddly, the mention of RaTG13 did not include any reference, footnote, or link to any previously published sequence.
Although the WIV didn’t provide details on this mysterious RaTG13 virus, a group of internet volunteers, including both amateurs as well as professional scientists working in their free time, began to investigate. This loose collection of open-source researchers, called DRASTIC, uncovered a medical thesis describing an outbreak of a mysterious disease in 2012. Six men who had been working in a bat-infested mine in Mojiang County, China, fell ill and were admitted to a hospital with symptoms including dry coughs, shortness of breath, fevers, muscle aches, headaches, and fatigue. Three of the men eventually died of this mysterious illness.
In the years following this incident, teams of researchers (including a team led by Dr. Shi Zhengli of the WIV) were sent to investigate the cause of this illness and collect samples from the Mojiang mine. This sampling led to the discovery of a novel SARS-like coronavirus in 2013, and a part of its genomic sequence was published under the name BtCoV/4991 in 2016.
The DRASTIC researchers discovered that RaTG13 was genetically identical to the BtCoV/4991 sequence from the Mojiang mine – it was the same virus, and had just been renamed for some reason, without any public record of the change. They also discovered that at least eight other closely related coronaviruses were also sampled from this mine and brought to the WIV.
Although unhelpful throughout the investigation, the WIV eventually verified these facts when pressed on them, and an addendum was added to the original paper confirming DRASTIC’s account of the origin of RaTG13.
So what should we make of this? Well, as I mentioned before, RaTG13 is no longer the closest known genetic match to SARS-CoV-2, so maybe the whole story is less important as it pertains to the origin of the pandemic. But the discovery of BANAL-52 doesn’t really resolve things either.[14] Laos is very far away from Wuhan (actually even further than Yunnan), so we’re left with the same question as before – how did SARS-CoV-2 make it all the way to Wuhan from such a distant natural reservoir without leaving a trail along the way?
A lot of the book is devoted to criticizing the Chinese government’s lack of transparency during the pandemic. Some brief examples:
At this point, we need to be cautious and police our emotions so that we don’t start favoring the lab leak hypothesis for non-scientific reasons. When reading about this stuff, it’s easy to get angry and start wanting the Chinese government to be guilty of something, but we need to consider all possible explanations.
It’s possible that the Chinese government was trying to cover up a lab leak, but it’s also possible that this was just regular authoritarian government behavior. Interestingly, Chan and Ridley describe similar attempts at obfuscation during the original SARS epidemic in 2003 (which had a natural origin), in which the Chinese government hid infected patients so that they wouldn’t be discovered by international health authorities. So I don’t think these attempts at obfuscation should necessarily be taken as evidence for a lab origin.
The book also criticizes a US-based research organization called the EcoHealth Alliance, and its president Peter Daszak.[17] The basic claim here, which I think has some merit, is that there was an attempt to artificially construct a scientific consensus from the top down, early on in the pandemic, even though such a consensus wasn’t (and isn’t) warranted by the evidence. This artificial scientific consensus was then picked up by tech companies, who used it to label discussion of the lab leak hypothesis as “misinformation”, as well as by media sources and fact checkers. I don’t want to get bogged down in all the convoluted details here, so I refer you to the book if you want to learn about it. It’s worth noting though that some of the scientists who publicly labeled the lab leak hypothesis as a “conspiracy theory” apparently considered it to be plausible in their private communications, which were obtained through FOIA requests.
Whatever we think of the whole Daszak / EcoHealth Alliance story, it’s pretty clear that at the start of the pandemic many respected institutions – scientific journals, tech companies, media networks, the WHO – expressed a level of confidence in the natural origins hypothesis that was not warranted by the evidence. How should we update our opinions based on this overconfidence? Does it tell us anything about the origins of the virus?
Let’s say that your friend claims he can magically predict the result of a fair coin flip (only once). “There’s a 100% chance it’ll come up heads,” he says. If you’re gullible, you’ll update your belief in favor of heads. If you’re feeling annoyed at your friend, you might update in favor of tails out of spite.[18] Both of these would be wrong. The correct answer would be to not update at all on the object-level question of the coin flip (still 50-50), and to update negatively on the separate question of how trustworthy your friend’s predictions are. And remember, even if the coin does come up heads, you should still update negatively on your friend’s trustworthiness – he was still overconfident even though he happened to get it right by chance.
This is basically how I think we should handle this unwarranted overconfidence from respected institutions – it should decrease our trust in these institutions, but we need to be careful not to start favoring the lab leak hypothesis out of spite. In my opinion this loss of trust should not really affect our view of the object-level question of the virus’s origin at all (although it would be nice to see some of the data being hidden, like that WIV database that was taken offline).
Sometimes your overconfident friend will get it wrong, and the coin will come up tails.
The book covers a lot of technical evidence that’s considered by some to point toward a lab origin. Although I’m a computational biologist myself, I don’t have the background knowledge required to evaluate this evidence, and have only been able to observe the back-and-forth debates between people who actually do have this background knowledge. So I didn’t update my opinion much based on these pieces of evidence, but I’ll still describe some of them here.
The first widely-cited piece of technical evidence has to do with the lack of rapid evolution of the virus early on in the pandemic. Some scientists claim that SARS-CoV-2 reached genetic stability early on, suggesting that it was already well-adapted to spread in humans at the start of the outbreak. Some have interpreted this as evidence that it was engineered for this purpose, or underwent serial passaging to encourage adaptation to human or humanized cells. Here’s a pre-print from May 2020 (on which Alina Chan is actually a co-author) making the claim that SARS-CoV-2 was already well-adapted to humans at the beginning of the pandemic. However, a review paper from proponents of the natural origins hypothesis disputes this claim, and offers several technical counterpoints, citing adaptive mutations later on in the pandemic that increased the virus’s fitness.
The second widely-cited piece of technical evidence is related to a feature of the SARS-CoV-2 called the furin cleavage site (FCS). The FCS increases the ability of the virus to infect certain types of cells, and is part of what makes SARS-CoV-2 especially contagious. It’s considered an unusual feature, and has not been found in the other viruses most closely related to SARS-CoV-2. It’s worth noting that previous gain of function research has included inserting a furin cleavage site into the original SARS virus from the 2003 epidemic. The debate over the FCS in SARS-CoV-2 is mostly related to sequence analysis, and I don’t have enough background knowledge on this to take a side on it either way. This is a paper by Rossana Segreto and Yuri Deigin claiming that the FCS may suggest genetic manipulation and point to a lab origin. For technical counterpoints on the FCS, I’ll refer you to the same review paper from natural origins proponents that I mentioned in the last paragraph.
A large chunk of the book is devoted to exploring these technical claims. These sections of the book are interesting and informative for hearing one perspective, but I definitely recommend checking out other sources with the technical counterpoints to get a full view of things. Personally I did not update my opinion based on these pieces of evidence because I don’t have enough background knowledge to evaluate opposing claims being made about them.
Also, I think it’s worth noting that the debates around these pieces of evidence are specifically related to the subset of lab leak possibilities that involves genetic engineering and manipulation. However, even if it were proven, beyond a doubt, that SARS-CoV-2 was not the product of genetic engineering, that would not rule out the possibility that it was a natural virus, collected from the field, that was stored in the WIV and leaked out. I want to point this out because I’ve seen some semantic confusion where people claim to “disprove” the lab leak hypothesis, when really they are given arguments specifically against the possibility of genetic engineering.
So far I’ve tried to summarize some of the key points of the book that I view as being the most important, but there are also a ton of other tiny pieces of information for us to try to make sense of.
Some of these bits are either false, misleading, or meaningless. For example, Chan and Ridley tell the story of Dr. Limeng Yan, a scientist-turned-whistleblower who fled to the US in April 2020 in fear of being “disappeared” in China. By all accounts, Dr. Yan started off as a legitimate whistleblower. She learned of COVID’s human-to-human transmission early on, when it was still being denied by the Chinese government, tried to report it up her chain of command (but was told to keep quiet), and ended up leaking the information to a Youtube commentator who told the world – and of course, it was confirmed by the Chinese government and WHO the next day. But instead of the story ending there, with Dr. Yan as a brave hero, things took a sad turn. She fled to the US in fear, but ended up in a situation where her only American contacts were people with their own political agendas (including Steve Bannon). Facing this scary and uncertain situation in a foreign land, it seems she basically told these people what they wanted to hear, and possibly ended up believing it herself through self-deception. Soon she was giving interviews to right-wing media outlets, spouting the actual unfounded conspiracy theory that SARS-CoV-2 was a bioweapon released by China on purpose, and other false information.
This is a sad story about a scientist who tried to do the right thing, but ended up intellectually corrupted by forces beyond her control. It’s also a reminder of how much noise and false information is out there.
It’s easy to dismiss the ridiculous claim that COVID began as a bioweapon, but other claims are more difficult to evaluate. For example, according to a US intelligence report, three researchers at the WIV became so severely ill in November 2019 that they required hospitalization. It was reported that they had symptoms consistent with both COVID-19 and regular seasonal illness. What should we make of this claim?[19]
After reading the book and going down several related rabbit holes, I feel as uncertain as ever about the origins of the COVID-19 pandemic. However, I have generally updated towards viewing the lab leak hypothesis as plausible, rather than an insane conspiracy theory. This partly due to this book, as well as many other related sources I came across last year.
To summarize, my overall updating went something like this:
There was a lesson I took away from this book that I’m not exactly sure how to feel about. Reading through the history of the investigation into the pandemic’s origins, it’s notable that many of the breakthroughs were made by either complete amateurs, or by scientists in fields outside of virology working in their free time.
For example, one of the main characters in this story is The Seeker, an anonymous Twitter user, later revealed to be a former science teacher in India with no formal research experience. Again and again, amateur internet researchers like The Seeker caught things that the professional virology community missed or ignored, including the origins of RaTG13 and the eight other coronavirus samples from the Mojiang mine.
I don’t really know how to feel about it. On the one hand, it’s pretty cool that science is now open source in a way that lets random, curious people comb through data to make interesting discoveries. But on the other hand, what the hell is going on if some random Twitter users are consistently correcting world-renowned virology institutes on various mistakes and omissions?
This is especially frustrating when the random guy on the internet turns out to be right.
When people talk about “trusting the experts”, I think they mean trusting people with technical expertise over people without technical expertise. This makes sense a lot of the time. Probably almost all the time. If you need your car fixed, have a weird rash on your skin, or have a leaking pipe in your house, you consult a mechanic, a dermatologist, or a plumber because they have the technical expertise you need on those issues. You don’t ask a random guy on Twitter for help.
But what if you have a question about investment banking on Wall Street, and how it should be regulated. Should you put the question to a bunch of investment bankers? After all, they do have the most technical expertise on this subject, right? They probably know more about investment banking than you or me, or a lot of the people pushing for more financial regulations.
Now we’ve run into an issue: they do have technical expertise, but it’s bundled together and intertwined with a bunch of incentives that could lead to biased judgment, so we can’t take what they’re saying as some pure, objective truth. Of course, their technical expertise is still valuable, so we shouldn’t necessarily throw out everything they say either. The proper response is to listen to what they’re saying and weigh the information accordingly after considering the incentives they’re facing, and possible biases.
I guess what I’m trying to say here is that scientific institutions, though probably not as bad as Wall Street, are still made up of human beings who are susceptible to all kinds of cognitive biases, including group think, confirmation bias, and the good ol’ Not Wanting To Be Wrong.
So what should we do about this? Well, the easy option is to just become an insane person, like Alex Jones, and assume the experts are lying all the time about everything. This strategy has the advantage of letting us feel edgy and rebellious, but it’s not very helpful if we actually want to figure these issues out. On the other hand, if we want to seriously try to discern truth from expert claims on controversial topics, that’s a messy challenge that involves considering their technical expertise, as well as potential biases they might have, as well as our own potential biases.
Conclusion 3: Some optimism about science
I know this has probably been a bit of a depressing post to read, but my final conclusion is actually one of optimism about the state of science. What differentiates science from other ways of knowing is its self-correction mechanisms. It’s all about changing our minds and reevaluating our beliefs based on new evidence and clearer understanding of things. This is basically what we’ve seen in the way the scientific community has changed positions on the lab leak hypothesis. Harsh critics might refer to this as a “flip flop”, or point out that the lab leak hypothesis never should have been dismissed in the first place, but I see it as a commendable error correction.
What’s even cooler is that much of this reevaluation was the result of amateurs and semi-amateurs making discoveries based on freely accessible genomic sequence data, and open source online sequence analysis tools. Plus the fact that, despite their lack of official credentials, their analysis was taken seriously (eventually), when it became evident that they were making good points. This is a credit to the scientific community.
Further sources to check out
