The Wuhan lab leak theory is more about politics than science

If Joe Biden’s security staff are up to the mark, a new report on the origins of the Covid-19 pandemic will be placed on the president’s desk this week. His team was given 90 days in May to review the virus’s origins after several US scientists indicated they were no longer certain about the source of Sars-CoV-2.

It will be intriguing to learn how Biden’s team answers the critically important questions that still surround the origins of Sars-CoV-2, the virus that causes Covid-19. Did it emerge because of natural viral spillovers from bats to another animal and then into humans? Or did it leak from the Wuhan Institute of Virology? And, if so, had it been enhanced to make it especially virulent?

These are important questions – to say the least. If we want to prevent another pandemic, it would be very useful to know how this one started. However, given the paucity of new information Biden’s team will have unearthed over the past three months – while the Chinese authorities have continued to provide little extra data – it is unlikely hard answers will be provided this week.

Although allegations of a leak from the Wuhan institute had been aired by Donald Trump, and rejected flatly by the Chinese, little credence was given to the claim until May, when 18 leading scientists sent a letter to the journal Science in which they claimed both spillover and leak theories were equally plausible. They also accused a recent World Health Organization investigation at Wuhan of not giving a balanced consideration to both scenarios.

News that the lab leak theory was being taken seriously by the new US administration triggered an onslaught from commentators, who have since alleged that the scientific establishment has been covering up for Chinese scientists’ errors. Among these accusations was one from Sir Richard Dearlove, former head of MI6, who claimed that “some scientific journals absolutely refused to publish anything that disagreed with the Chinese view”.

The main evidence to support a lab leak rests on the failure of scientists to pinpoint the intermediate animal that picked up the virus from bats and passed it to humans. In addition, the Wuhan institute is home to a laboratory that is headed by the virologist Shi Zhengli, who tracked down the bat origins of the last coronavirus Sars epidemic.

Her team specialises in collecting coronaviruses. Thus, one of the world’s coronavirus research centres was situated in the city where Covid-19 first materialised – a coincidence that some conspiracy advocates find too much to accept.

Shi has rejected claims she had been working on enhancing a new virus to make it more virulent or that she or her staff had been infected with a new coronavirus that they had collected, a view supported by a recent review by scientists in the journal Cell: “Despite extensive contact tracing of early cases during the Covid-19 pandemic, there have been no reported cases related to any laboratory staff at the WIV [Wuhan Institute of Virology] and all staff in the laboratory of Dr Shi Zhengli were said to be seronegative for Sars-CoV-2 when tested in March 2020,” it states.

The fact that Sars-CoV-2 is highly transmissible among humans has also raised suspicions that it had been genetically enhanced. This notion is dismissed by Professor David Robertson, of Glasgow University’s centre for virus research.

Fiddling with viruses in laboratories is not the dangerous activity. The real threat comes from the wildlife trade

“Yes, the virus is spread by asymptomatic carriers and that is perfect for human transmission. So how does a natural virus like that come into existence? It is so good at infecting humans, after all. But it is not just a human virus. We find it in pangolins. It goes from humans to mink very easily and it has infected deer in the US. It isn’t a human- adapted virus. It is what we call a generalist or promiscuous virus.”

However, the prospect that Covid-19 emerged from a lab leak was taken very seriously by some senior scientists, including Sir Jeremy Farrar, head of the Wellcome Trust. As he makes clear in his recent book, Spike: The Virus v the People, his initial – horrified – reaction to the emergence of Covid-19 was that it could have escaped from a virus research centre. Only intense consultations with other researchers caused him to change his mind.

“As things currently stand, the evidence strongly suggests that Covid-19 arose after a natural spillover event, but nobody is yet in a position to rule out an alternative,” he said.

This point is backed by Professor James Wood, of Cambridge University. “I think there is very strong evidence for this being caused by natural spillovers but that argument simply does not suit some political groups. They promote the idea that Covid-19 was caused by a lab leak because such a claim deflects attention from increasing evidence that indicates biodiversity loss, deforestation and wildlife trade – which increase the dangers of natural spillovers – are the real dangers that we face from pandemics.”

In other words, fiddling with viruses in laboratories is not the dangerous activity. The real threat comes from the wildlife trade, bulldozing rainforests and clearing wildernesses to provide land for farms and to gain access to mines. As vegetation and wildlife are destroyed, countless species of viruses and the bacteria they host are set loose to seek new hosts, such as humans and domestic livestock. This has happened with HIV, Sars and very probably Covid-19.

And that, for many scientists, is the real lesson of Covid-19.

• This article was amended on 22 August 2021 to refer to Shi Zhengli at second mention as “Shi”, that being her surname.