The controversial Covid lab leak theory – once dismissed as a fringe conspiracy – is back in the spotlight this week after the FBI ruled that the virus “most likely” originated from a “Chinese government-controlled lab.”

This is the first public confirmation of the US intelligence agency’s classified judgement of how Covid emerged. However, the lack of transparency of the bureau’s investigation means the conclusion isn’t particularly enlightening for the global scientific community: “There’s not a whole lot of details I can share that aren’t classified,” said FBI Director Christopher Wray. 

The announcement comes in the same week that the US Department of Energy concluded with “low confidence” that the virus was accidentally leaked from a Wuhan laboratory. The Chinese government has responded defensively, accusing Washington of “political manipulation.”

Over three years after Covid-19 was first detected in the city of Wuhan, questions over the origins of the virus remain shrouded in mystery.

The natural “spillover” theory – that the zoonotic virus spread naturally from animals to humans without the involvement of any scientists or laboratories – is still considered the most plausible explanation by many in the scientific community, including the WHO. 

That said, the lab leak theory has moved from fringe to mainstream

This possible explanation emerged early in the pandemic, enthusiastically taken up by Donald Trump, but it soon became mixed up with far-fetched conspiracy theories about Beijing engineering the virus as a biological weapon to unleash on the world. 

Yet as time went on, it’s become increasingly clear that the possibility of an accidental lab leak warrants serious investigation. 

The Wuhan Institute of Virology (WIV) is the world’s leading virus laboratory when it comes to collecting large numbers of bat coronaviruses and experimenting on them. It’s also a mere 40-minute drive from the Huanan wet market where the first cluster of infections emerged.

Lab leak theorists suggest one of the WIV researchers may have become accidentally infected either with a natural virus collected from the wild, or a lab-made one. And in 2021, a US intelligence report claimed that three researchers at the Wuhan laboratory were treated in hospital as early as November 2019, just before the virus began infecting humans in the city. 

In 2021, a joint China-WHO investigation into the origins of the virus concluded that the lab leak theory was “extremely unlikely”. But a global body of scientists has cast doubt on the credibility of their findings. China’s insistence on a “joint inquiry” meant involving Liang Wannian – the man who oversaw the country’s response to Covid-19 – in the investigation. 

If the virus had indeed leaked from the WIV, this would have implications not just for China but for the global scientific research community, and for the US government too. 

Research conducted at the Wuhan Institute of Virology has been part of a major international effort to investigate the threat of new human pandemics. The institute’s work has involved collaborations with American scientists and generous amounts of US funding. 

The type of research conducted there, known as “gain-of-function”, manipulates viruses to make them more infectious or more deadly. These high-profile experiments have generated heated controversy among virologists. Advocates say this method is vital to help us anticipate how viruses might emerge in the wild. Others believe the risk of accidentally sparking off a man-made pandemic with a lab-made virus is too high. 

According to an extremely extensive Vanity Fair investigation (which is well worth reading), in one US State Department meeting, officials seeking to demand transparency from the Chinese government say they were explicitly told by colleagues not to explore the Wuhan Institute of Virology’s gain-of-function research, because it would bring unwelcome attention to U.S. government funding of it.

These conflicts of interest paired with the lack of co-operation from Beijing are hindering chances of reaching any firm conclusions about how Covid-19 first emerged. Yet understanding its origins are vital to mitigate the risk of similar disasters emerging in the future.

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