Did COVID escape from a Wuhan lab?

Did COVID escape from a Wuhan lab?

The lab-leak hypothesis has moved on from its initial wing-nut conspiracy theory status to being seriously considered. Not too long ago (May 14, 2021), 18 reputable scientists published a letter in Science asking for a deeper investigation into the origins of COVID. Within the opening paragraph they write …

Theories of accidental release from a lab and zoonotic spillover both remain viable. Knowing how COVID-19 emerged is critical for informing global strategies to mitigate the risk of future outbreaks.

Is the lab-leak hypothesis truly credible?

Politico has a very interesting insight into this. They reached out to various subject matter experts, both those who do find the lab-leak hypothesis to be credible and those that don’t. They asked to explain their thinking, and so got some interesting insights into it all.

We can read it all, both sides, and by grasping the full conversation, not just one side, come to a provisional conclusion.

Experts who consider Lab-Leak Hypothesis possible

Via that Politico article …

“Much of the currently available information suggests that a lab-based origin of Covid-19 is plausible. There remains no sign of an intermediate animal host that could have passed the virus to humans in 2019. There is no evidence that live mammals were sold at the Wuhan seafood market in 2019, and none of hundreds of animal samples collected from that market had any trace of the virus. In other words, there is zero evidence that supports a zoonotic origin of the virus that excludes the involvement of research activity.

“There are copious precedents of pathogens leaking from labs — the original 2003 SARS virus leaked up to six times from labs across three countries. Consider that the SARS research and animal infection experiments at the Wuhan Institute of Virology, for more than 10 years, were all performed at relatively low biosafety levels. It is currently not possible to tell from the genetic evidence whether the virus ever passed through a laboratory or a lab personnel. 

“The question is: How did a virus, whose lineage is found only in southern China, make its way into humans in the metropolitan city of Wuhan, more than a thousand miles away? We know that the Wuhan Institute of Virology had possibly the greatest collection of SARS viruses from numerous trips across China. We know that they were working with a batch of viruses very closely related to SARS-CoV-2. Details of these viruses and the experiments performed with them have not been shared in a timely manner.” 

Alina Chan, molecular biologist at the Broad Institute of MIT and Harvard

“It is worthy of a careful, rigorous, unbiased, objective examination, based on relevant, verifiable data. There are a number of plausible scenarios embedded in this label, ‘lab leak,’ and importantly, they include an unrecognized infection of a well-intentioned lab worker attempting to recover or study new coronaviruses from bats. It does not imply malice or even necessarily awareness (of the accident). Lab accidents are much more common than any of us know, or would like to admit, and they occur worldwide and even in the most safe and secure labs. U.S. biosafety labs are by no means strangers to accidents; leaks of some of the most dangerous infectious agents have occurred at CDC and other U.S. government labs.” 

David A. Relman, microbiologist at Stanford University

Experts who consider Lab-Leak Hypothesis improbable

“Coronaviruses in nature are immensely diverse and certainly capable of causing epidemics without human manipulation, for example SARS, OC34, and MERS viruses. Lab-manipulated viruses tend to be constructed using pieces from known viruses. SARS-CoV-2 does not closely resemble any previously characterized virus. When viruses have been in the freezer for many years, scientists can see the missing years of evolution in the viral genome. When viruses escaped from labs, they looked like viruses that had been kept in labs. When H1N1 reemerged in 1977, it was missing 27 years of evolution due its time in the deep freeze. The most probable origin scenario remains a natural zoonosis from bats or an intermediate animal host.” 

Joel Wertheim, evolutionary biologist at the University of California San Diego

“Lab leak scenarios are obviously inconsistent with several established facts regarding the origin of SARS-CoV-2, including the fact that the majority of early cases were linked to different markets that sold wildlife or wildlife products in Wuhan. Theories on SARS-CoV-2 must also account for the fact that two distinct lineages of SARS-CoV-2 (lineage A and lineage B) were distributed at different Wuhan wildlife markets.

“The original SARS-CoV outbreaks in 2002-2004 were linked to the wildlife trade. Several independent sources indicate that wildlife species susceptible to SARS-CoV-2, including civets and raccoon dogs, were sold at the Huanan market and other wildlife markets in Wuhan. Linkage of the origin of SARS-CoV-2 to wildlife or the wildlife trade fully accounts for the fact that the majority of early Wuhan Covid-19 cases were linked to different wildlife markets in a straightforward manner. It provides simple explanations for the fact that two different genetic lineages of SARS-CoV-2 were linked to different markets.” 

Robert Garry, virologist at Tulane Medical School

“The lab leak hypotheses remain speculative and unsupported — unlike the hypothesis of natural emergence, which is supported directly by epidemiological, serological and genomic data, and indirectly supported by precedence and ecological data. There are no examples of lab escapes of novel, previously unknown, viruses having led to outbreaks, let alone pandemics. Famous examples of SARS, H1N1 and Ebola were all caused by known viruses — which have already been ‘selected’ for their ability to infect humans — the same is not true for a virus randomly sampled by a researcher from a bat. We have a myriad of examples of natural zoonotic emergence events leading to human outbreaks — that include the emergence of SARS in November 2002 in China and the first detection of HKU-1 in January 2004, also in China. Note the timing of these coronavirus emergence events — all happened over the winter months, with both SARS-CoV and SARS-CoV-2 happening in the month of November.”

Kristian Andersen, virologist at Scripps Research Institute


Personally, I find that the “highly improbable” arguments are the most compelling and for that reason, I lean very much towards it not being an accidental lab-leak.

I might of course be wrong, but until there is sufficient evidence or argument to support it, then your best bet is to stick with the lab-leak origin being “improbable”.

Side Observation: I’ve seen somebody tweet an extract from the “It is possible” section and completely ignore the rather more robust counter arguments within the “It is highly improbable” section. Where there is an existing lab-leak conclusion being embraced, some will literally cherry pick the stuff that aligns with it and discard the bits that don’t. The terms used for that include “motivated reasoning” and also “confirmation bias


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