As we reflect on five years since the tumultuous start of the COVID pandemic (even if we just wish to forget it ever happened), the most fundamental question is still unanswered: where did SARS-CoV-2 (the virus that causes COVID) come from?
There are two theories: market (or zoonosis) and lab leak. In my mind, neither theory is proven. The bar for proof in science is high, and both theories only have circumstantial evidence in their favor. I won’t “both-sides” this question, though: while absolute proof remains elusive, the available evidence lopsidedly favors a lab leak.
Both theories have two things in common: that SARS-CoV-2 emerged in Wuhan, China, and that it has a viral ancestor that infects bats. The market hypothesis holds that the virus jumped into some animal species from bats, and then, at the Huanan Seafood Market, into humans. A wide variety of wild animals were offered for sale at the market. The argument is that pandemics have always arisen from zoonosis: pathogens jumping from animals to humans. Wild animals as both a food source and the pathway of infection is not strange, and can be seen right here in California, with tularemia (a bacterial infection, named after Tulare County where it was first identified) sometimes infecting small game hunters.
With COVID, the would-be culprit species has not been identified. SARS-CoV-2 genetic material found at the market is from environmental samples,which could have come from infected humans. Detecting SARS-CoV-2 in wild animal populations isn’t hard; the virus now infects North American white-tailed deer, in which it has been sampled regularly. Not to mention household dogs and cats at high levels. Moreover, scientific journal articles postulating the zoonosis as the last word on COVID origins have technical flaws that render them moot.
The lab leak hypothesis is simpler and explains the emergence of SARS-CoV-2 as an escape from the Wuhan Institute of Virology (WIV), a research laboratory that is a center of coronavirus research. Insight into the type of research conducted at the WIV comes from its collaborations with scientists in the west, including the United States. The DEFUSE grant proposal of New York City-based EcoHealth Alliance, a nonprofit research organization, and its collaborators at the University of North Carolina and elsewhere, is one example. This proposal, to DARPA, was not funded — but it shows the nature of experimental virology in the years prior to covid.
The DEFUSE proposal sought to sample wild bat viruses and study them in the lab, using gain-of-function virology, and infection of humanized mice. Gain-of-function virology, which the US government banned for a time, ostensibly exists as a learn-by-tinkering approach, although successful knowledge acquisition remains elusive. One curious feature of SARS-CoV-2 is called a furin cleavage site (FCS), something DEFUSE proposed to study, and which is present in SARS-CoV-2 but no other sarbecoviruses, or members of the same subgenus. We also know from a recent publication that the WIV works with potentially-dangerous bat viruses at biosafety level 2 (BSL-2), which is inadequate and irresponsible.
The lab leak theory in a nutshell: some experiment similar to that proposed in DEFUSE was conducted, and the virus escaped the lab, which is not unusual. This explains why Wuhan, why the FCS, why no infected species of Chinese fauna, as well as the extreme resistance of the scientific establishment to talk about COVID origins. What is more, use of humanized mice likely explains why COVID started like a house on fire — instead of haltingly, like bird flu.
The Trump administration recently declassified the CIA’s assessment of COVID origins — under the Biden administration — as being likely a lab origin, with low certainty. This has been characterized by some as a politicization (from the right) of the scientific debate on COVID origins. It could just as easily be viewed as a politicization (from the left) by those who kept this assessment classified. What national-security principles were served by keeping this information from the public?
Who has been standing in the way of getting to the bottom of all this, apart from the Chinese government? The US National Institutes of Health (NIH), a funder of gain-of-function virology in general and of the WIV in particular (Francis Collins and Anthony Fauci, the past directors of the NIH and of the National Institute for Allergy and Infectious Diseases, respectively, were both enthusiastic proponents of gain-of-function). The biotech industry and its allied news outlets, experimental virologists LARPing as epidemiologists. Scientists everywhere, who take offense to the notion that a science experiment gone wrong could have caused the pandemic. And especially the self-styled “scicomm” community, carrying water for science, and, often, industry.
Studying the origin of COVID is crucial to preventing the next pandemic. We cannot pretend we “have the tools” if we do not understand the origins of COVID . We need to keep striving for more information; we can start at the NIH. Greater transparency about NIH’s role in funding gain-of-function research in the recent past is step one. Those involved in risky virology, who expressed concern themselves, can help with a public accounting of their own. Public health dodges this question at its own peril.
Andrew Noymer is associate professor in population health & disease prevention at the Joe C Wen School of Population & Public Health at the University of California, Irvine.