CoVid-19: natural occurrence or lab leak?

Three days ago, National Geographic website ran a story about the origins of the CoVid-19 pandemic, following on a US National Intelligence Council investigation published 2 weeks ago.  21 months into the global pandemic, it is still appropriate to address this question – and to me the answer is as elusive – and as fascinating – as ever

At the end of August the US Intelligence agencies released their conclusion about the origins of CoVid-19.  They considered 3 possible explanations:

  1. The Chinese had engineered the virus as a biological weapon
  2. There was bona fide research on coronaviruses taking place in the Wuhan laboratory, and the virus had escaped by accident 
  3. The virus that infected humans had naturally crossed species from bat via another animal to human
  • The first option was discounted by all the experts, but both traditional and social media will continue to propound that as a theory!
  • However, the US experts could not agree, despite all the months of consideration, on which of the other two conclusions was most likely.  This is what the report said
  • Knowing the answer is vitally important for the future of our species!  
    • If CoVid-19 was a zoonotic disease (ie defined simply as one that normally affects one species but can spread to another), then we could take steps to limit human contact with animals
    • If CoVid-19 had been the result of a laboratory accident, the world needs to tighten up even more on lab safety
  • To be honest the majority opinion on the NIC was that, more likely than not, infection was natural, but this was not unanimous.  In this post, I consider some of the evidence in both directions in detail 

The evidence from previous CoVid virus epidemics of transmission between species

Firstly, it is not disputed from 2 previous C0Vid virus outbreaks that those epidemics were caused by natural infection spreading from a bat via an intermediate animal 

2002 SARS-CoV 

  • This is now widely agreed to have spread from horseshoe bats to live palm civets (a wild cat) – sold in live animal markets in Guangdong- province in southeast China – and then to humans
  • The evidence for this is based on research showing how genetically identical the civet virus was to the SARS virus in humans
  • The virus isolated from a civet from that live animal market was 99.8% genetically identical to human SARS
  • Further the virus was not present in other civets not found in the animal market
  • How the virus got into the market civet was not known for sure but, in 2012, in bat caves in Yunnan, a province in southwest China, researchers found almost by accident the same genetic sequence in the bat virus as that found in both the wet market civet and in humans carrying SARS virus

2012 MERS-CoV

  • The first case was a business man in Jeddah who died from respiratory failure
  • Given what had been found with SARS, MERS  was also thought to have spread from bats to humans but there were two unknowns: the genetic details were not available, and no middle step had been identified
  • The latter was resolved in 2013 when a camel owner went down with MERS and, on analysing the blood from his herd, there was again almost complete genetic similarity between the CoVid virus found in the camel and the infected human

What was found in the wet markets in Hunan province  in 2020?

  • Some of this information was gathered by the team of World Health organisation (WHO) scientists who had been given some access to some of the Chinese laboratory data and other results.
  • WHO discovered that in 2020, Chinese researchers took more than 2000 samples from a variety of  live and frozen animals from the market and also from wild animals near by
  • The WHO report implied that all these samples were negative for CoVid-19
  • However it is possible that by the time the sampling was done in 2020, there were no affected animals
  • Then there is the pangolin story!
  • Pangolins are supposed to be a protected species but are trafficked to make handbags etc
  • Pangolins did carry CoVid-19 but the genetic similarity between pangolin and human virus was inconclusive – about 85-90% – and further pangolins were not sold in the Hunan market

What about the role of bats?

  • For sure, many species of bats in China carry coronaviruses
  • Chinese researchers found coronaviruses with genetic sequences close to the human CoVid-19 in caves in Yunnan
  • Similarly coronaviruses with genetic sequences close to the human CoVid-19 have also been found in other countries including Thailand and Cambodia
  • The problem is that the genetic similarity with the bat virus is not as high as found with bat virus in both SARS and MERS and, this genetic data is really not conclusive 

How to explain that a bat virus could suddenly infect humans?

  • One missing piece of the jigsaw is why should a bat virus, which is harmless to bats, ‘out of the blue’ be able to infect humans?
  • We know that the virus can only get into our cells by sticking to them and taking over the complex mechanisms to then enter cells: these bits of the virus were not though to be naturally present in the bat.
  • How did this genetic change in the bat virus occur to make them more likely to infect us, some argued that would have required this to have been ‘manufactured’ in a lab
  • However in 2020 detailed analysis of other coronaviruses isolated from bats and pangolins had demonstrated the some of these properties were available.
  • Why this research is important is that it argues against one aspect of the laboratory error theory  
    • That theory was that the CoVid-19 virus emerged from the Wuhan laboratory’s genetic research
    • Further that without such research, the CoVid-19 virus would not have had the ability to enter and infect humans

And what is the evidence that CoVid-19 comes from a laboratory leak?

  • Some of this was gathered by the team of World Health organisation (WHO) scientists who had been given some access to some of the Chinese laboratory data and other results.
  • The first is the obvious coincidence is that the epidemic started in the area containing the world famous coronavirus research lab – but the answer is that the lab was there because it was close to the bat caves where they needed to be
  • The Wuhan Institute  of Virology reported that their research showed no match between the bat coronaviruses they were investigating and the CoVid-19 strains, but these actual records were not available to the WHO team investigating the origins of the pandemic 
  • There was a report in the Wall Street Journal in May this year suggesting that 3 lab workers in Wuhan had had a mysterious illness in November 2019
  • There are no other sickness data from the workers in the laboratory in 2019 suggesting CoVid-19 infection, but one issue is whether “no data” means no data or no evidence
  • There is however one fascinating piece of evidence was reported in in the National Geographic article this week!
  • Between 2014 and 2019, the US National Institutes of Health had funded a collaborative research project between a research group in New York  based ‘EcoHealth Alliance’ and Wuhan
  • This research involved engineering a natural bat coronavirus and adding a spike protein so it could more easily enter human cells
  • This is the same spike protein that has caused all the damage to humans
  • A virological expert approached by National Geographic however dismissed this as irrelevant, as the bat coronavirus in this experiment was not the same as CoVid-19

Have laboratory leaks caused virus infections before?

  • The short answer is yes!
  • Indeed, the National Geographic article reported lab workers in several Asian countries working on CoVid-19 who had becoming infected
  • By way of personal interest, the last case of smallpox in the world happened tragically from a laboratory  error in Birmingham – and the junior doctor who cared for the woman who died became one of my closest research colleagues 

My conclusion on if we will we ever get the answer?

  • It is plausible that CoVid-19 could have spread from bats to other animals and then to humans, but the genetic data – whilst strong – is not absolute
  • Conversely, the data suggesting a lab leak is all circumstantial – but cannot be discounted 
  • So I don’t see how this question – one of the most important to arise globally – can ever be properly answered

5 replies on “CoVid-19: natural occurrence or lab leak?”

And what is the evidence that Covid-19 comes from a laboratory leak?

Some of this was gathered by the team of World Health organisation (WHO) scientists who had been given SOME access to SOME of the Chinese laboratory data and other results.

Some access to Some of the laboratory date – but not all access!


I worked on laboratory design, including bio-safety labs, for several years. The information available from various published sources, that most of the Wuhan laboratories were not only designed (the technical aspect) but also operated (the management aspect) to BSL-2 or BSL-3 standards (while similar work in the UK would be to BSL-4) is highly disquieting. This sounds like an accident waiting to happen, to say the least.

Liked by 1 person

That’s so interesting. Of course in this case there is the normal issue of airflow etc but if there was genetic manipulation of the virus that would add a whole additional layer of complexity


a) airflow is of course part of both the design AND the operating aspects, such as e.g. how and under what circumstances operators would change from safety gear to outdoor wear,
b) some of the international scientists (not only USA and UK) also took the view that to experiment on ‘gain of function’ (genetic manipulation) is not only highly dangerous but also IMMORAL for anyone.


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