More evidence that COVID-19 had a zoonotic (animal) origin and didn’t come from a lab

August 19, 2021 • 10:30 am

“Zoonotic,” in case you didn’t know, refers to an infectious disease transmitted between animals. And, in a post a few days ago, I highlighted a paper in Science suggesting that the coronavirus did originate as a zoonotic disease: it came from horseshoe bats and was transferred by bats to another mammal (one likely candidate is the palm civet or “civet cat”, a viverrid, not a felid), and then from this mammalian carrier to humans in Wuhan “wet markets.” The authors emphasized that there was no evidence that the virus came out of the local lab.

A new paper in press in Cell comes to the same conclusion, though they summarize all the evidence, not just the phylogenetic evidence (family tree of viruses). The new paper, however, is not as certain about the species of mammal that transferred the virus from bat to human. But they are pretty sure that the virus was not cultured in the Wuhan Institute of Virology (WIV), and then either escaped or was somehow released to cause disease. This paper, which Matthew called to my attention, has an international team of distinguished disease experts as authors, and they summarize all the evidence that COVID-19 is a purely zoonotic disease and escaped from a Wuhan wet market, not from the WIV. The paper is really only 11 pages long, and you can download the pdf by clicking on the screenshot below.

I’ll just summarize the lines of evidence (there’s more in the paper, too, but the first 11 pages of double-spaced text is all you need to read.

1.) All previous coronavirus infections of humans (viruses other than SARS-CoV2, or what I’ll call COVID-19) have a zoonotic origin, several of which had their origin in “wet markets” selling animals like civet cats and raccoon dogs. Workers in these markets have high concentrations of antibodies against various coronaviruses.

2.) The sequence of COVID-19 is similar to that of other coronaviruses in humans known to have zoonotic origins.

3.) Epidemiologically, the spread of the virus strongly implicates the wet market in Wuhan as the source, not the WIV.  As the authors note:

Based on epidemiological data, the Huanan market in Wuhan was an early and major epicenter of SARS-CoV-2 infection. Two of the three earliest documented COVID-19 cases were directly linked to this market selling wild animals, as were 28% of all cases reported in December 2019 (WHO, 2021). Overall, 55% of cases during December 2019 had an exposure to either the Huanan or other markets in Wuhan, with these cases more prevalent in the first half of that month (WHO, 2021). Examination of the locations of early cases shows that most cluster around the Huanan market, located north of the Yangtze river (Figure 1B-E), although case reporting may be subject to sampling biases reflecting the density and age structure of the population in central Wuhan, and exact location of some early cases is uncertain. These districts were also the first to exhibit excess pneumonia deaths in January 2020 (Figure 1F-H), a metric that is less susceptible to the potential biases associated with case reporting. There is no epidemiological link to any other locality in Wuhan, including the Wuhan Institute of Virology (WIV) located south of the Yangtze and the subject of considerable speculation. Although some early cases do not have a direct epidemiological link to a market (WHO, 2021), this is expected given high rates of asymptomatic transmission and undocumented secondary transmission events, and was similarly observed in early SARS-CoV cases in Foshan (Xu et al., 2004).

If you’re a conspiracy theorist that the virus was released from the lab by mistake, you’d have to say that it somehow got itself over to the wet market before it started infecting people. The wet market, not the WIV, was the epicenter of the infection.

4.) The COVID-19 virus was actually detected in “environmental samples” taken in the Hunan wet market, especially in the part of the market that sold animals and animal parts.

5.) As I showed in my post two days ago, the viruses closest in sequence to the human COVID-19 virus are three bat viruses from Yunnan. (It’s still not clear how they or their relatives found their way to the Yunnan wet market). But the telling part is, as the authors say, “None of these three closer viruses were collected by the WIV and all were sequenced after the pandemic had begun.”

6.) The absence of the known intermediate animal host for COVID-19 does not suggest that the virus was clearly engineered by humans in the lab, for the animal source of many human pathogens of zoonotic origin, including Hepatitis-C, polio, and Ebola, have not been identified.

7.) Although there have been isolated incidents in labs in which people got infected with viruses, there’s been only one documented example of a pandemic coming from human origin: “the 1977 A/H1N1 flu epidemic, that most likely originated from a large-scale vaccine challenge trial.” There are no epidemics known caused by the escape of a novel virus. (You might respond that, “Well, this could be the first one,” but the other evidence I adduce tells against this.)

8.) There is no evidence that the WIV or any other lab was working on the SARS-CoV-2 virus or any related virus before the pandemic.

9.) Despite extensive attempts to find the virus in workers at the WIV, there are no reports of COVID-19 infections in that institute.

10.) Previous experimental work on coronaviruses at the WIV have involved inserting a “genetic backbone” and other genetic markers that we do not see in the human COVID-19 virus that’s causing the pandemic.

11.) To culture the virus in the lab, workers would have to infect wild-type mice, but were unable to do so with SARS-CoV-2.  The virus has since been engineered to be culture-able in mice, but that occurred after the pandemic had already begun.

12.) Adaptive mutations that enhanced the infectivity of the virus arose after the pandemic started, ergo were not engineered in the lab.

13.) Sequences that “lab-contaminant” advocates say could only have been engineered into the virus by humans have in fact been found naturally in other coronaviruses. That they’re missing in close relatives of the coronavirus could reflect only our pretty profound ignorance of what strains SARS-CoV-2 evolved from from.  And there is no evidence that that kind of genetic engineering was ever going on at WIV.

The “conclusions” on pp. 10-11 are pretty clear:

“the most parsimonious explanation for the origin of SARS-CoV-2 is a zoonotic event” involving transfer from an intermediate host in a Wuhan wet market.

“There is currently no evidence that SARS-CoV-2 has a laboratory origin.”

And the last paragraph:

We contend that although the animal reservoir for SARS-CoV-2 has not been identified and the key species may not have been tested, in contrast to other scenarios there is substantial body of scientific evidence supporting a zoonotic origin. While the possibility of a laboratory accident cannot be entirely dismissed, and may be near impossible to falsify, this conduit for emergence is highly unlikely relative to the numerous and repeated human-animal contacts that occur routinely in the wildlife trade. Failure to comprehensively investigate the zoonotic origin through collaborative and carefully coordinated studies would leave the world vulnerable to future pandemics arising from the same human activities that have repeatedly put us on a collision course with novel viruses.

This paper is of course tentative, like all such conclusions, but the data add up to a “normal” zoonotic event and not escape from the lab. It’s clear the virus was not engineered to kill humans as a bioweapon, as there’s no evidence that the WIV worked on it. And even if it did, why would it happen to escape to a wet market—places where these viruses are known to exist naturally.  Nor is there evidence that the WIV was simply studying the virus and it escaped as an accident that caused the pandemic.

In other words, conspiracy theories about the virus seem to be untenable, but, humans being human and prone to conspiracies, they’ll persist.

UPDATE: in the thread after this tweet, third author Rasmussen goes through the evidence that people think supports a lab origin, and then dispels it:

h/t: Matthew

57 thoughts on “More evidence that COVID-19 had a zoonotic (animal) origin and didn’t come from a lab

  1. I’ve always thought that a zoonotic origin was much more likely than a lab leak, but that debate on the issue (in both the scientific and lay media) should be allowed unfettered.

    So, the question from the beginning of the epidemic remains: where are the calls to ban these so-called “wet markets”? Besides being viral and bacterial reservoirs, they are epicenters of animal suffering and over-exploitation (often of endangered species), and they need to be shut down permanently.

    Is the media not pushing for that in order to avoid offending the Chinese and their “traditional” practices? Or would that be too Trumpian?

    1. What would be “Trumpian” is to claim that the Chinese SARS-CoV2 and unleashed it on the US as the “China Virus.” I never once heard Trump say anything that might offend “traditional” Chinese practices (other than running up trade deficits) or otherwise say anything in support of alleviating animal suffering or over-exploitation.

      Hell, speaking of “traditional practices,” Trump bragged that his good buddy Xi came up with the ultimate remedy for drug addiction — the death penalty.

    2. The Wuhan wet market is closed as far as I’ve heard. But correct enough that wet markets need to stop. Everywhere. Problem is, that is hard to do in most places due to deep corruption, strongly held local traditions, and ineffective policing in remote areas. So we are likely to see this anew.

      1. You’ve put this correctly, Mark. I’ve been to China many times and can corroborate your reasons for the continued existence of the wet markets, especially the point about local traditions. I’ve not been in a wet market but have walked passed one, and I can tell you it reeks to high heaven. The stench is disgusting/revolting. I can smell it in my memory as I write this, ew! I would add that one can walk the sidewalks of some cities in China and encounter mini wet markets here and there. I encountered one that offered, among other live animals, snakes that the proprietor would slaughter for customers. Yes, these local wet markets will be next to impossible to eliminate in the near future, and so it’s just a matter of time before we get a new zoonotic disease from one of them, sad to say.

  2. Some “conspiracy theory” points as outlined by Robert Redfield and Marc Siegel in a recent WSJ essay:

    On September 12, 2019, coronavirus bat sequences were deleted from the Wuhan Institute’s database.

    Security protocols were changed for the Institute.

    600m was requested for a new ventilation system.

    Employees of the Wuhan Institute became ill with Covid-like symptoms in the autumn of 2019.

    A Harvard satellite study revealed a shutdown of traffic around the Wuhan lab late summer/early fall.

    Shortly thereafter, hospital parking lots started to fill.

    Biological implausibility of a virus emanating from a bat cave and infecting millions.

    All circumstantial as stated by the authors, but worthy of reconciliation with a zoonotic origin.

    1. I’m not arguing for any particular hypothesis, but I can’t help but point out that a zoonotic origin is not incompatible with a lab origin in general, only specific lab origin hypotheses. Of course, it depends on exactly what one means by origin. Made here, very unlikely, but first jumped into humans here is much less unlikely.

        1. Much less unlikely than that the virus was made in a lab, because that is so unlikely pretty much anything else is less unlikely.

          As I said I’m not arguing for any particular scenario. And I didn’t mean my comment as an argument against this paper. I simply wanted to point out that in general a zoonotic origin doesn’t rule out a lab origin because for all the months this has been talked about lots of people on all “sides” have argued as if the one would exclude the other.

          1. No fair using your brain! Knowledge comes from the gut!

            Probability of origin in a wet market : in collecting bats for lab study : in biowarfare engineering :: mass of the sun :: mass of the earth :: mass of Trump’s two neurons that connect

    2. I can’t read the article w/o enrolling. But the smattering of info does not persuade. “Innuendo and out the other”, as they say.
      >According to the article easily accessed from the above Tweet, extensive testing of Wuhan personnel for C-19 exposure was negative after the time frame that was claimed. So I don’t see the necessary corroborating evidence of early illnesses from C-19.
      >And stating that its biologically implausible that all this could start from a bat cave is just padding the resume’.

    1. I have been told this is due to the Greek origins of the word. But I’m not sure if that is correct. There are two Os in the Greek alphabet, omega and omicron. Omicron is short, omega is long. There are a number of examples of this, such as cooperation, oopherectomy, microorganism.

    2. And the noun plural is zoonoses. Which inevitably makes me think of elephants and tapirs as having notable zoonoses.

    1. Thank you for this. I thought it was an excellent summary. I am a physician and find myself dragged into all kinds of debates. This will help. Also, I would very much like to comment on Facebook. But I am not being given the option.

    2. In the medical world we say “zoo-on-osis” – but we are famous for mangling and mispronouncing all sorts of classically-derived words.

  3. It’s true that there’s only been one ‘human origin’ pandemic to date. But there have been some close calls (the Marburg outbreak was a particularly scary example). Even the conspiracy-mongers pushing the WVI origin theory haven’t (in most cases) claimed that bioweapons research was the source, but it’s very worrisome that something as lethal as Marburg got released even into the closed population of the Frankfurt and Belgrade labs. I get the feeling sometimes that we’ve really been pushing our luck on this. Gain-of-function isn’t really necessary, in a lot of cases, to lead to dangerous consequences for everyone; just a bit of laziness and negligence can do it. The evidence for zoonotic origins for Covid seems quite strong, but something that should not be ignored is the fact, noted in the MIT Tech Review (, that the lab hazard protocols for viral research at the WVI were BSL-2—far lower than the original work along these lines carried out in the US at Baric’s lab. To my mind, that’s the damning takeaway from the virology lab debate, and it’s not just China—clearly, as Marburg attests, this kind of thing may show up in Western lab work as well. We’re trusting too much to luck, I fear, and as Baric is quoted as saying, ‘If you study a hundred different bat viruses, your luck may run out.’

    1. I’m not sure what this is about ophthalmologists, Rand Paul is one, as is Assad. I hope this is completely incidental, after all, ‘Dr Glaukomflecken’ is one too.

  4. Figure 1 B-F is classic epidemiology—in the tradition of John Snow’s London cholera map, which
    founded the science. That, and the sequence data, certainly make a convincing case. As others have commented, why is there no world-wide campaign against Chinese wet markets? Interesting that China, so authoritarian in other respects, has apparently not attempted to do anything about them, despite the now abundant evidence for their role in zoonotic disease transmission.

  5. Somewhere I saw a graphic map of Wuhan, with the cases of COVID blocked in, showing month by month how it spread. It was very obvious that it started spreading from the wet market, and didn’t reach the WIV area until several months later.

    I believe the resurgence of wet markets is partly attributed to the loss of all those pigs in China during the swine fever days of 2019, so that people were looking for pork substitutes.

  6. “If you’re a conspiracy theorist that the virus was released from the lab by mistake, you’d have to say that it somehow got itself over to the wet market before it started infecting people. The wet market, not the WIV, was the epicenter of the infection.”

    If your ‘conspiracy’ is that China may have misrepresented initial data, or withheld it, in order to use cases nearby the wet market as the supposed first cases, rather than its original source, then it isn’t very surprising that the epidemiologists would come to the incorrect conclusion that it originated in the wet market.

    I have to say that firstly, it isn’t paranoid or foolish to think that China’s government might control or obstruct investigation into matters they think might reflect badly on the state. The readers of this blog ought to know better than most that China regulates basically all opinions appearing in their country. But when you suggest that they might have also tried to manage and alter the evidence regarding a disease spreading out of their control originating in their country, suddenly you are misrepresented as a fool.

    Secondly, most of the scientific investigators come to reasonable conclusions *if you assume that the information they have was correct*. But they are not very good at investigating the possibility of human obfuscation or lies.

    If there were many cases of coronavirus, or that had symptoms similar to coronavirus that were not conclusively diagnosed, prior to the wet market outbreak, and these cases were simply not reported, then it would completely change the identification of that place as the epicenter. ​

    But the actions of the WIV prior to the officially acknowledged beginning of the outbreak are bizarre. Why take a database about viruses offline in September 2019, and then justify it as protecting from cyberattacks over Covid, when the world didn’t know about Covid until December-January, and when the earliest official cases even now are supposed to have been from November?

    Why lie about the deaths of people from bat coronaviruses in 2012, misrepresenting them as fungal infections?

    You might object, of course, and say something like “How could China have controlled the dissemination of all of this information?” But we are talking about a society that tries to micromanage the dissemination of all information by its citizens.

    It is completely possible that this originated as a zoonotic transmission without any laboratory storage or manipulation. But people aren’t looking at the alternative very hard, or the odd behavior of the institute, the damage control immediately managed by a scientist with a conflict of interest, etc.

    To put it differently, if someone was found to have died by falling off a bridge, you might rule it an accident or a suicide without any issues. If you discovered that there was a second person who had been on the bridge at the same time who later lied about being there, had constructed a fake alibi, and then returned later to try to alter the scene of the death, it might be a good idea to consider an alternative hypothesis of murder, even if there were no physically noticeable differences between these two hypotheses in the victim’s autopsy.

    That is why all of the scientists dissecting data don’t really address the issue that these conspiracy theorists are interested in. The scientists merely talk past them, accepting the data that China allowed the rest of the world to take at face value.

        1. I’m a firm believer in the cock-up theory of history winning out massively over the conspiracy theory of history, and I don’t subscribe to any conspiracy theories. But we should ask ourselves this: is it more likely that China would control information to save face, or more likely they would be completely open about any deficiency in their system that led to the infliction of the pandemic on the rest of the world? Leaving aside all questions about gain-of-function and biowarfare, never mind a deliberate release and other deranged ideas, I think it quite reasonable based on what we know of China that to consider it possible they would cover up anything that could be criticised, and if so, we can’t really trust their information about where cases started, whether WIV staff were infected etc. We are left wondering about what is the most likely explanation in the absence of any firm trail of evidence. Of course, if you believe China has been perfectly honest and open, you’d better take seriously their suggestion that US special forces planted the virus in Wuhan!

    1. Well, I don’t see the conspiracy cabal drilling down into any genomic data trying to find anything. And I don’t see the scientists that I listen to, on This Week in Virology (now thrice-weekly) talking past anything, either.

      IIRC, Vincent Racaniello, the indefatigable host there, knows the head of the WIV as a fellow virologist. They were at the same conference together in late 2019. It seems to me that it would be highly unlikely for the head of an institute trying to subvert the world would have Western contacts, nor that she would be at a conference outside China if she was scrambling her institute to cover things up. Also, Western scientists were working there at the time.

      For a recent TWiV on this from just six wks ago, have a look at epitope 774. Start around 22:00 if in a hurry.

    2. The missing sequences (deleted, you seem to imply, as part of some devious plot) were still available elsewhere online and have been rediscovered. The linked Nature report says that the recovered sequences were only important in suggesting that the virus was circulating in Wuhan before the big outbreak at the wet market. Thus, the outbreak at the wet market may have been a superspreader event started by an outsider and not directly related to the commercialization of live animals there.

      1. This was to be my exact point, including this reference.
        We are getting a couple conspiracists popping up here, going on and on about these mysteriously deleted sequences. But the sequences in question were just raw preliminary sequences, and removing them to post cleaner data elsewhere is not really a smoking gun for conspiracy. And the raw sequences were recovered in the cloud.
        Sheesh, people. Let it go.

      2. Indeed, it seems that by the end of 2019 the virus was already present in Europe, not just in Wuhan. Antibodies against Sars-CoV-2 have been found in biosamples of Italian cancer patients collected in September 2019; RNA sequences corresponding to the virus were present in sewage waters from Barcelona, Milan and Turin in December 2019; the first Covid-19 patient in a French intensive care unit is from december 2019 (the disease was diagnosed later).

  7. (It’s still not clear how [the three bat viruses from Yunnan] or their relatives found their way to the Yunnan wet market).

    I may be wrong, but I don’t think that they did. From the map in the Science paper, they had simply been collected from three different places in Yunnan province in 2018/19/20.

      1. Maybe I missed it, but I didn’t see anywhere in the Science paper that those three were collected from wet markets, that’s all.

        There was a (WHO, IIRC) expedition earlier this year hunting for SARS-CoV-2 relatives, and that returned with 10 or so that were close (and at first I thought the Science paper was using some of those), but what I recall from that was that all samples came from bat caves.

  8. Sure there are versions of the lab leak hypothesis that are driven by conspiratorial thinking, suspicion of the CCP, and a dose of racism. And yes some people have weird ideas about the melting point of structural steel or whatever.

    I agree the evidence doesn’t point strongly toward a lab origin. The evidence so far doesn’t point conclusively to any specific origin of SARS-CoV-2.

    But it’s not conspiracy thinking to note that:
    1. the only documented route by which bat SARS-CoV-2-like coronaviruses like RaTG13 got to Wuhan from bat caves in southwestern China is in collections by WIV researchers; and
    2. the animal intermediate host might have been a civet or something else but SARS-CoV-2 has still not been found in an animal in the wild; and
    3. bat SARS-like coronaviruses have never proved to be highly transmissible from humans to humans immediately after zoonotic transmission from the animal host, so it is normal to wonder how SARS-CoV-2 evolved that unusual ability.

    There might be good answers to all of those issues but so far there are not afaik. In my view that warrants keeping an open mind. I don’t understand what’s controversial or conspiratorial about that.

    1. The article I posted a few days ago said that horseshoe bats are widely distributed in China. The sequences most similar to those from the coronavirus come from Yunnan, but they haven’t sampled other bats around Wuhan. Here’s a distribution map of one species: Note that it’s found around Wuhan.

      This article notes that they found viral DNA in the wet market. “Following its closure, SARS-CoV-2 was detected in environmental samples at the Huanan market, primarily in the western section that traded in wildlife and domestic animal products, as well as in associated drainage areas (WHO, 2021)”. Is that good enough?

      As for #3, there is mutation.

      1. Thanks for the reply.

        Yes horseshoe bats are found elsewhere than Yunnan, including near Wuhan. I would find evidence of SARS-CoV-2 in those Wuhan bats to be more convincing.

        Mark emphasizes below that WIV in Wuhan was set up there to study local bats & viruses, but the SARS-like samples collected by the WIV researchers come from Yunnan not from Wuhan afaik. I agree with Mark that it’s hard to nail down the intermediate host, but it was done successfully for both SARS and for MERS.

        Yes that is relatively convincing that SARS-CoV-2 was found in the environmental samples. That does seem to put it at the market. It doesn’t show what mammal it came from (could have come from humans at the market, not from any of the food animals at the market). But I agree this is good evidence for the zoonosis hypothesis.

        For obvious reasons, I will decline to disagree with you about how molecular evolution works 🙂 But isn’t mutation alone an unlikely cause? Selection is needed. Gain-of-function experiments at WIV seem a plausible source of that selection. But I concede that is only plausible and not demonstrated.

        So I’m coming around to the zoonosis hypothesis and I’m prepared to abandon the lab leak hypothesis. But finding the intermediate host seems critically important to me. And now I’ve overcommented so will stop. Thanks again for replies, this is an interesting conversation.

    2. #1 There has long been a lot of concern about the possibility of indigenous viruses going from bats –> humans in that geographic area. Hence the big research institute in Wuhan – in the midst of that geographic area. Hence researchers at said institute collected early samples from the area, And so of course the first documented samples turned up in their freezers.
      #2. It is often very difficult to nail down the previous host species when a virus jumps to a new species. The geographic and genetic landscapes are complex and vast, and the genetic landscape is meanwhile changing. The # of people who can do the monitoring is not large. We may never nail the intermediate host of this virus, but that is not unusual.
      #3 The current thinking is that it looks like from bat –> other host (civet cats, maybe) –> humans. So it does not need to directly go from bat to human. And from the article at the Tweet above: “Subsequent serological surveys found ~3% positivity rates to SARS-related coronaviruses (SARSr-CoV) in residents of Yunnan province living close to bat caves (Wang et al., 2018)”. So that implies that related viruses either can go from bats to humans, or from bats to something else to humans.

  9. Looking forward to reading this review in its entirity – thanks Jerry.

    I think one really interesting point that hasn’t been mentioned in this post yet is that two lineages (dubbed A and B) that differ by two nucleotides, were found in early patient samples in China. The authors of this review touch on this somewhat briefly and suggest this may indicate two distinct spillover events. The Huanan wet market was specifically a super spreader event for Lineage B.

    To me the existence of these two early lineages is also suggestive of a purely natural origin not involving the labs at WIV but I could be missing something and I haven’t found a good discussion of this particular point yet.

  10. Wet markets in China exist mainly for “medicinal” purposes – woo – as opposed to for protein like in Africa. With its industrial agriculture protein is cheap in China – in China they eat bats for “respiration” and rhino horns for ED.
    (Further, African markets aren’t as densely populated with animals.)

    On with the woo of Trad’l Chinese “Medicine”, the unscientific nonsense and environmental-rape that got us here:
    The PRC has been VERY aggressive (even bullying the WHO to include it as legitimate) for soft power cultural reasons and profit. Meanwhile (democratic) Taiwan has been trying to “encourage” their population to not use it and deregistering the number of TCM shops there.
    In a very real sense magical thinking plus communism got us here.

  11. This may be of interest –
    Have artificial lighting and noise pollution caused zoonosis and the COVID-19 pandemic? A review

    “In this article, we propose a new theory by which human pollution such as artificial lighting and noise accentuate pathogen shedding from bats and other wild habitants in urban environments. ….
    artificial lighting attracts insectivorous bats to congregate around streetlights, resulting in changes in their diets and improved likelihood of close contact with humans and animals.”

  12. Well, IMHO there are clues against WIV involvement in the published literature. Just compare these two articles with predicted and actual structures:

    The authors, as I understand, are American colleagues of WIV group and they clearly got the predicted structure wrong the first time (note the confident title of the first article).

    Just before Covid the two groups wrote this article (it was published later):

    And before that these two:

    So they are doing it in the open with their American colleagues, for years and just before the pandemic, producing gain-of-function viruses on the bat platform and making kompromat on themselves. And then we got Covid – bat-pangolin recombinant with non-optimal furin site etc, clearly different from those they were working on and from those they were expecting.

    You just can’t make it look like this. They were unprepared.

  13. I think 3) is much weaker than the authors suggest:

    Overall, 55% of cases during December 2019 had an exposure to either the Huanan or other markets in Wuhan, with these cases more prevalent in the first half of that month (WHO, 2021).

    This implies that not all cases had an exposure to the Huanan wildlife market. We know SARS-CoV-2 spreads through superspreading events. The fact that large numbers of cases came from the wildlife market doesn’t mean it originated there. Though the fact that there are people from the Huanan market exposed over most of the month makes me think a staff member got infected. This makes me think zoonosis is more likely.

    4) doesn’t distinguish between the lab escape and zoonosis scenarios. The virus could have made its way to the market from the lab.

    If I remember correctly, the viruses mentioned in 5) diverged 70 years ago. Which “side” this supports is left as an exercise to the reader.

    I think points 8) and 9) are extremely weak evidence because the CCP’s actions over this entire pandemic are to save face first and only solve the problem if face has already been lost. They definitely will not allow any hint of wrongdoing, or even anything that raises the likelihood of them having done wrong, to come to light.

    10) I think is the strongest evidence against the virus being from a lab.

  14. Thank you for posting this, I’ll have to give this paper a read. I expressed skepticism of zoonotic origin in the other post about COVID-19 origins but just from the points you list here it seems like the authors made a real effort to address many lines of evidence instead of handwaving as I feel other papers do.

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