Covid-19: leak from Chinese lab cannot be ruled out, says former head of China’s Centre for Disease Control

China's former top immunologist and virologist has said that the theory that the Covid-19 virus came from a laboratory in the country cannot be definitively ruled out, although most experts agree it remains unlikely.

Professor George Gao, who was head of China’s Centre for Disease Control (CDC), made the statement while appearing on the BBC Radio 4 podcast 'Fever: The Hunt for Covid’s Origin'. His words contrast explanations given by the Chinese government, which has continued to deny that the virus which locked down much of the world originated in a laboratory in the country - and dismissed other theories as coming from "anti-China forces".

Prof Gao retired from the CDC last year. He is now vice president of the National Natural Science Foundation of China.

A number of theories have circulated around the origins of the deadly virus, which has contributed to almost 7 million deaths worldwide according to the World Health Organisation (WHO). This includes it spreading from cross-contamination from a bat in a Wuhan market, with bats commonly carrying the SARS- CoV2 virus.

Prof Gao's words come after the FBI director Christopher Wray was quoted in February 2023 as saying that a lab in China was "most likely" the source of the virus. However, this view is not the consensus amongst US intelligence agencies on the matter.

What did Professor George Gao say about the origins of the Covid-19 virus?

Speaking on the BBC Radio 4 podcast, Prof Gao was questioned about the theory that the virus originated in a lab. In response he said: “You can always suspect anything. That’s science. Don’t rule out anything.”

The Wuhan Institute of Virology (WIV) is one of the country's top labs. Scientists at the institution are known to have studied coronaviruses in its labs, with the lab leak theory speculating that the virus spread from a leak in the building.

However, Gao told the BBC programme that the lab had been "double-checked by the experts in the field” and he had "heard" that there were no issues which arose from this investigation but he has not seen the full result. He added: “I think their conclusion is that they are following all the protocols. They haven’t found [any] wrongdoing.”

The Chinese government has consistently refuted claims that Covid spread from a leak in a laboratory. When questioned by the BBC on the words of Prof Gao, the Chinese Embassy said: “The so-called ‘lab leak’ is a lie created by anti-China forces. It is politically motivated and has no scientific basis.”

What have scientists said about the 'lab-leak' theory?

Scientists investigating the source of Covid-19 have said that the evidence points towards the likely scenario that it came from natural origins. The natural origin in this instance is the contamination from animals to humans.

WHO led an investigation into the outbreak. Experts at the organisation ruled that it was "extremely unlikely" that it originated from a laboratory leak, however they were prohibited from conducting a second phase of the investigation.

The second phase would have involved audits of the laboratories in Wuhan. However the Chinese government rejected the request.

While WHO ruled it was "extremely unlikely" to have originated from a laboratory, the organisation echoed Gao's comments in saying that it cannot be ruled out entirely.

In March 2023 after US media reported that the US Energy Department had concluded that the virus stemmed from a lab-leak, Tedros Adhanom Ghebreyesus, director-general of WHO, said of the investigation: "I wish to be very clear that WHO has not abandoned any plans to identify the origins of the Covid-19 pandemic.

He added: "I have written to and spoken with high-level Chinese leaders on multiple occasions as recently as just a few weeks ago... all hypotheses on the origins of the virus remain on the table."