TL:DR I thought back in early 2020 it probably had a natural origin, and despite all the attention given to the possibility of a lab leak, I still think the natural origin is most likely.
If you want to know why, read on.
There are four stages to this argument:
- Why the evidence for a lab leak is weak
- Why the evidence for a natural origin is strong
- How to think about situations where a government might be lying to you, and conspiracy theories in general
- What the origin of covid-19 means for our plans to prevent future pandemics
In the long-ago times of March 2020, I wrote a short story for New Scientist arguing that SARS-CoV-2 probably wasn’t engineered as a bioweapon and was more likely to have evolved in the wild.
Let me start by acknowledging the elephant in the room. Because I wrote a story early in the pandemic arguing that covid-19 probably had a natural origin, I'm conscious I might be engaging in motivated reasoning to back up that conclusion. After all, it's embarrassing to be publicly wrong and it can be emotionally easier to double down. I don't know that I can do anything to convince you, or indeed myself, that I'm not biased. All I can say is that I have asked myself this question and take the possibility of motivated reasoning seriously. Furthermore, I've read a lot of the material that purports to support the idea of a lab leak. I tried to do so with an open mind, and there have been several instances where new facts emerged that did make me question my original conclusion. I can only present the facts as I understand them and the reasoning I've applied, and you can judge for yourself whether it hangs together.
With that in mind, off we go.
The New Scientist story has since been updated by another writer, Graham Lawton, and I think it’s better for it. In particular, it does a better job of distinguishing two questions, which should be considered separately:
- Was the virus engineered by humans?
- Did it get into the human population via a lab leak?
Let’s tackle them one by one.
First, most virologists will tell you that SARS-CoV-2 is not the product of bioengineering. That’s because its genome doesn’t contain any obvious signs of having been engineered.
You might argue that the engineering could have been done in a clever way that doesn’t leave any traces. Obviously, I can’t disprove that. But in that case I would want some form of evidence that this happened.
It’s been reported that the Wuhan Institute of Virology (WIV) applied to do gain-of-function experiments. These are studies that would produce a new and dangerous virus, in order to study it and be prepared. They’re very controversial because they could potentially cause an outbreak.
However, the WIV applications were rejected. Of course, it’s possible that the experiments were done anyway, in secret. But again, where is the evidence of that?
Now let’s consider whether the virus got into the human population via a leak from the lab. In this scenario, the WIV collected SARS-CoV-2 from the wild but did a bad job of storing it. Again, there is no hard evidence that the WIV had SARS-CoV-2 in its collection until the virus started spreading.
At this point, many readers will baulk, and not unreasonably. “You keep saying there’s no evidence, but the Chinese government is secretive and covers things up!” is the retort.
This shouldn’t need saying, but clearly the Chinese government is not to be trusted. It’s authoritarian, secretive, and guilty of genocide against the Uyghurs.
However, it’s wrong to take that as evidence for the lab leak hypothesis. That’s because, whichever covid origin story turns out to be true, the Chinese government is at fault.
If the virus escaped from a government-run Chinese lab, that’s the government’s fault, e.g. for not being strict enough about biosecurity. Equally, if it originated in the wild animal trade, that’s also the Chinese government’s fault: they have been warned about the risk of disease outbreaks from the animal trade for years.
Set against this is the fact that diseases spill from animals to humans with depressing regularity, and the strong evidence that the Huanan Seafood Wholesale Market in Wuhan was the epicentre of the pandemic.
A study published in July 2022 found that the first clusters of cases occurred in and around the market, plus environmental traces of the virus in sections of the market where live covid-susceptible mammals were sold. This suggests there were animals in the market that had the virus, and that it passed to humans from them.
It’s possible to poke a few holes in that scenario: we don’t know what those animals were; maybe it was actually the vendor that was infected; maybe someone from the WIV had SARS-CoV-2 and went to the market.
But can you see how we’re having to fiddle around the edges of a body of evidence if we want to get away from an origin in the wildlife trade? Whereas the lab leak evidence is much more conjecture?
I find it useful to step back and think about conspiracy theories in general. How can we decide whether a conspiracy theory is likely to be true, or is just silly?
After all, conspiracies do happen. Watergate, COINTELPRO, Iran-Contra and the Rawalpindi conspiracy all really happened, but if they weren’t documented they could easily sound ludicrous and unbelievable.
Fortunately, there are some useful metrics we can use.
One is how many people have to be in on the secret. The more people are involved in the conspiracy, the more likely it is that the secret will get out. This is one of the (many) reasons not to believe the Moon landings were faked: thousands of people would have to be in on it. (I can't resist linking to the Mitchell and Webb moon landing conspiracy sketch) If SARS-CoV-2 was made in a lab, or leaked from a lab, quite a lot of people would know and I think we’d have heard from some of them by now.
However, in this case I think the crucial question is whether the evidence is direct or indirect.
When I say direct evidence, I mean something like the Watergate tapes in which you can hear Nixon and his allies conspiring to commit crimes. Or, to give a more contemporary example, Matt Hancock’s WhatsApp history.
In contrast, indirect evidence means facts that can be interpreted as suspicious, but could also just be random or innocuous.
The problem with indirect evidence is that if you look hard enough you’ll always find it, because the historical record is always messy. Plenty of people have pointed out over the years that truth is stranger than fiction, because fiction has to make sense.
For instance, it’s been reported that some staff from the WIV went to hospital with respiratory infections in late 2019. That looks suspicious, right? Maybe they had covid-19!
Think about it for a minute. Autumn and winter are the times when respiratory viruses like influenza and RSV infect us all. Given how many people work at the WIV, it would be surprising if a few didn’t go to hospital with respiratory bugs at that time every year.
If you could show that the number of WIV staff with respiratory illnesses was unusually high in late 2019, compared to previous years, that might be circumstantial evidence. But the fact that a handful of them were ill means nothing. It shouldn’t sway us at all, because it’s what would happen in a normal year.
This is the tricky thing about the lab leak hypothesis, and many other conspiracy theories. It’s possible to pile up lots of semi-suspicious details, like the people with the respiratory illness – and the accumulation of detail looks damning. But each piece of evidence is negligible, so all it is is a whole lot of nothing.
This does not mean I am dead set against a lab leak. It's completely possible and we should try to find out. A whistle-blower from the WIV could sway me, as could physical evidence from within the lab, or verifiable records of experiments. These would all constitute direct evidence that SARS-CoV-2 was there before the virus started spreading.
Similarly, some of the reports supporting the lab leak hypothesis come from government organisations like the FBI. They might have access to classified material that the rest of us don't know about. Maybe some of that material is compelling direct evidence of the sort I'm talking about. But it's notable that the intelligence organisations say that they have low confidence in their assessments, which suggests to me that they don't have a smoking gun. Until and unless they share their evidence, we don't know how much weight to put on it.
In the absence of such direct evidence, I’ll continue to be swayed by the considerable evidence that the virus evolved naturally and started spreading among humans at the Huanan Market.
Finally, how important is this debate for deciding what to do to prevent future pandemics? I'd suggest, hardly at all.
We ought to review biosecurity protocols, but that's because those things ought to be reviewed on a regular basis anyway! It would also be good if labs like the WIV were more transparent, but again that would be true either way.
Meanwhile there's been thousands of disease outbreaks over the last 40 years and many of them came from animals. In the World Disasters Report 2022 that I produced for the Red Cross (IFRC), I wrote:
“A 2014 study compiled 33 years of disease data from 1980 to 2013. This encompassed 12,102 outbreaks of 215 human infectious diseases. The researchers controlled for confounders such as improvements in disease surveillance. They found significant increases in the total number of outbreaks and in the diversity of diseases. In the early 1980s, there were fewer than 1,000 disease outbreaks per year, but by the late 2000s this had tripled to over 3,000. Bacteria and viruses caused 88% of the outbreaks. Similarly, zoonoses – diseases entering the human population from animals – were responsible for 56% of outbreaks (Smith et al, 2014).”
Even if covid-19 is one of the estimated 44% of outbreaks that don’t originate in animals, that shouldn't sway us much. Zoonoses are still a major threat and we still need to take action to make them less likely. That needs a One Health approach, in which human and animal healthcare are integrated, e.g. doing joint surveillance for a disease in both humans and animals.
It would be slightly weird if we had hundreds of zoonoses that never quite turned into pandemics, and then the one lab leak incident did become a pandemic. But hey: sometimes history is weird. Nobody would believe the story of the Titanic if it weren’t demonstrably true.
The fact is, diseases that come from animals, and from other “obvious” sources like dirty water, are some of the biggest threats to our health. They’re also low-hanging fruit: we largely know how to prevent them, and the money spent would be paid back many times over in lives, productivity and happiness.
All of this was true before anybody had heard of covid-19, and it is still true now. The pandemic didn’t actually change our understanding of disease risks very much. What it ought to be is a call to arms, because I never want to have to go through anything like it again.