The debate over the origins of Covid-19 has always been a hot topic and these days it seems more like a war than a scientific debate.
Some say that ground zero of the pandemic was a live animal market in Wuhan, China. Others claim that SARS-CoV-2 (the coronavirus that causes Covid-19) emerged from a nearby laboratory that was studying similar viruses. Both are plausible scenarios.
Defenders of the market hypothesis have been aggressively vocal recently. In August 2024, an anonymous editor in a leading medical journal spoke of “the need to support alternative hypotheses” and “ideas more in line with popular movies.”
In a commentary in another journal, he complained that scientists were being bullied for rejecting the hypothesis that the virus had leaked from a lab. The same man then attacked a younger researcher who favored that hypothesis.
It is true that the virus was present in the Wuhan market. Samples collected from stalls and sewers in early January 2020 contain SARS-CoV-2 genetic material. A recent analysis of this material, published in the journal Cell, shows that the common ancestor of the market viruses was the common ancestor of the entire pandemic.
That sounds appealing, until you realize that all of these samples were collected weeks after the pandemic began, and none came from a live animal. Irresponsibly, none of the samples were collected before the market was closed and the animals were destroyed. That's why most scientists consider these latest results suggestive rather than definitive.
The lack of animal samples is a problem. No one believes that this virus originated in Wuhan. The natural reservoirs of SARS-like coronaviruses are in bats, and no infected colonies have been found within 1500 kilometers of the city. So the virus was released into the market. However, it is not found in the supply chains of animals sold there.
Could a person rather than an animal have brought the virus to the market in late 2019? It’s quite possible. Many of the viruses near the base of the ancient SARS-CoV-2 virus tree came from people with no connection to the market. Some, including the cluster from Guangdong province, weren’t even from Wuhan.
Despite the many uncertainties and unanswered questions, it would be much easier to accept the market hypothesis if the pandemic had started in one of the hundreds (or perhaps thousands – no one seems to know for sure) other Chinese cities that had similar markets in 2020. After all, the 2002 outbreak of the original SARS coronavirus (a very close relative of SARS-CoV-2) began in a market selling cats and other animals in the city of Guangdong.
However, the epicenter of the Covid-19 pandemic was less than 20 kilometers from China’s prominent coronavirus research lab, the Wuhan Institute of Virology. It’s an extraordinary coincidence, and it would take convincing evidence that the market is the source (or that the lab is not) to rule it out. The evidence we have is not that strong.
There is no evidence – at least not that Chinese officials have shared – that the virus was present at the Wuhan Institute of Virology, although there were several closely related viruses.
Scientists from the Institute have been on coronavirus-hunting expeditions in places like Guangdong. Scientists from the Centers for Disease Control and Prevention in Wuhan — just a five-minute walk from the market — have also been on their own expeditions. There is an obvious and plausible alternative route to the first human case.
However, as of March 2020, the idea that a lab was involved in any way is now being dismissed as a conspiracy theory. Two years ago, one of the most ardent supporters of the market hypothesis claimed that his latest research had refuted the idea that the virus had escaped from a lab. The author of the new analysis in the journal Cell says that alternative explanations are “fantastic” and “absurd.”
Who is all this “chaos” supposed to benefit? Not the scientists who can read the research papers, note the warnings, and make their own judgments. Not the politicians who have taken an ideological stance on the issue, especially in the US. And not the intelligence agencies that many believe are our best hope for getting to the truth.
So, we still don't know how the Covid-19 pandemic started. But we do know that the issue is important and that debate should be encouraged, not stifled.
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