These include the couple’s Chinese origins, a Royal Canadian Mounted Police investigation into possible policy breaches at the lab, and that Qiu sent live viruses to the Wuhan Institute of Virology four months before her ouster.

The sense of mystery reached the Canadian parliament last month, with the head of the Public Health Agency of Canada (PHAC) refusing to discuss the matter under heated questioning from frustrated MPs at a hearing of the Special Committee on Canada-China Relations.

PHAC President Iain Stewart, called before the March 22 hearing, told foreign affairs critic for the opposition Conservative Party Michael Chong that the scientists’ case “was the subject of an investigation, it is a security investigation, and I’m not going to be able to talk about the details”.

Stewart would not even say whether they had been fired, merely that they no longer worked for the agency. Fellow Conservative Garnett Genuis tried a different tack, asking if the agency had ever terminated a scientist for security breaches or the improper transfer of viruses.

When Stewart sidestepped again by saying it was “a very difficult question to answer”, Genuis erupted.

“I’m glad you have a bloody senior office in this country where you’re supposed to account to parliamentarians and the Canadian people. Now answer the damn question,” said Genuis, calling it a “critical issue of national security” and Stewart’s refusal to answer an “utter disgrace”.

But Stewart would not budge, citing legal advice, and later writing to the MPs to tell them that privacy laws prevented further discussion about why Qiu and Cheng no longer work for PHAC, their employment having officially ended on January 20.

The couple has maintained their silence, and they could not be reached for comment.

Watching the situation unfold has been Dr Gary Kobinger, Qiu’s former boss at the Winnipeg lab, which is Canada’s only Level Four virology facility, capable of handling the world’s deadliest pathogens.

He praised her as among a “rare breed” of scientists, focused and hardworking, who “doesn’t stick to keeping things the way they are, so she takes risks. But it is a field that is constrained within all sorts of standard operating procedures”.

Research is a team effort, said Kobinger, but it was Qiu who led the way with her Ebola research that resulted in the development of the ZMapp antibody treatment for the virus.

“In a team effort you still need someone to lead it, and she was the leader of the project. She did a fantastic job,” he said.

Kobinger said he had not spoken to Qiu since 2019, and he was puzzled by her departure from the lab that July, and its dramatic fashion.

“I was surprised. My perception – and I say this without having been there at the time – was that she just kept doing what we were doing,” he said.

But the key question remains unanswered: what prompted the investigation of Qiu and Cheng?

A virus shipment to Wuhan

The most fevered discussions about the scientists have already been debunked: no, Qiu did not send coronaviruses to Wuhan, PHAC said, and her departure had nothing to do with the March 31, 2019 virus shipment to China, which involved live Ebola and Henipaviruses.

Qiu’s role in sending the deadly viruses was confirmed by a freedom of information request by national broadcaster CBC.

The transfer of such material sounds alarming, but Qiu’s pre-existing status as a celebrated Ebola researcher has sometimes been lost in the subsequent discussion.

Now a professor at Quebec’s Laval University, Kobinger worked at the Winnipeg lab for 11 years, mostly as chief of its special pathogens programme. Before he left the lab in 2016 he signed a recommendation for Qiu to be promoted, having worked closely with her for the previous six years.

02:24

Coronavirus: A look inside China’s Wuhan Institute of Virology

Coronavirus: A look inside China’s Wuhan Institute of Virology

He told the South China Morning Post that he was “absolutely” confident in her abilities, and “she deserved, 200 per cent, all of the accolades and awards she won” as a result of the work that led to ZMapp.

Her husband, Cheng, is a widely cited biologist, whose published work has included research into HIV and Sars (severe acute respiratory syndrome). But Qiu, who headed the Winnipeg lab’s vaccine and antiviral therapies section, is the more acclaimed of the pair.

Qiu had moved to Canada from China in 1996 for graduate studies that included working on antibody treatments, according to a profile published by Canada’s Public Policy Forum after she and Kobinger won the 2018 Governor General’s Innovation Award for ZMapp.

‘Interesting day’ for WHO Covid-19 team at China’s Wuhan virology lab

She began looking for an Ebola cure in 2005, searching for a combination of naturally occurring antibodies that could stem a fatality rate that ranges up to 90 per cent, depending on the strain.

During a round of budget cuts at the lab as Kobinger was trying to decide which projects would have to be put on ice, he and Qiu designed a set of experiments that saved her programme – and ultimately yielded ZMapp.

“We needed a miracle piece of data, which we did record,” said Kobinger.

Their theories were put to the test in 2014, as an Ebola outbreak ravaged parts of West Africa. It would go on to kill more than 11,000 people.

According to the US Centres for Disease Control and Prevention (CDC), the outbreak had a fatality rate of about 40 per cent.

ZMapp was given to 28 patients, of whom 25 made complete recoveries.

The first person to receive ZMapp was Dr Kent Brantly, the Texan missionary doctor whose battle with the disease, his role as a human guinea pig, and remarkable recovery made headlines around the world.

He credited ZMapp with saving his life, saying he felt his fever break 15 minutes after receiving the treatment, and he visited Qiu and Kobinger at the Winnipeg lab in 2018 to thank them in person.

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The US National Institutes of Health said in 2016 that ZMapp had produced a 40 per cent lower risk of death in a randomised trial conducted later in the West Africa outbreak, although its efficacy has since been surpassed by other antibody treatments.

Nevertheless, Kobinger said, “ZMapp was the first that showed you could cure Ebola when you had advanced disease”.

Qiu was quoted in the Public Policy Forum profile as saying “we never gave up … antibody treatment until that time had failed. They didn’t believe it was going to work. We proved that it did”.

ZMapp also provided a road map for research into treating a host of other diseases – including Covid-19, said Kobinger.

He even attributed the experimental “Trump cocktail” used to treat the former US president last October in part to Qiu’s work. “It’s exactly the same recipe,” he said of the treatment, although he acknowledged other scientists might disagree.

“So many labs are developing antibody therapies for other diseases,” Qiu was quoted as saying by the office of Canada’s governor general in her award citation. “I’m very happy. It’s not just that we found a cure for Ebola, but our work is having an impact on the whole scientific community.”

That legacy has largely been neglected by the general public in the controversy since Qiu and Cheng were removed from the government lab on July 5, 2019.

The virus shipment to the Wuhan Institute of Virology in particular captured the public imagination, amid unsubstantiated suggestions that the pandemic began with a leak from the Chinese lab.

Robert Redfield, who served as head of the US CDC under Donald Trump, said last month that the “most likely etiology of this pathogen in Wuhan was from a laboratory, escaped”.

Others are dubious. The chairman of the World Health Organization team investigating the pandemic’s origins, Peter Ben Embarek, said in February that the lab leak theory was “extremely unlikely”, and it “isn’t a hypothesis we suggest implies further study”.

Kobinger said it was not frequent – but not unheard of – for the National Microbiology Laboratory to send live viruses to other countries.

“You don’t do this every week. These are rare requests. But they do happen,” he said.

Ebola viruses might be used as “reference strains” for diagnostic purposes, he said.

“So we did share those strains with others. And as you can imagine they don’t originally come from Canada. We obtained them from other countries … two years before my departure, we sent a strain to the US, for example,” he said.

And whatever the reason for Qiu’s situation, Kobinger said there was no mystery about the value of her previous work.

“We can say, mathematically, that this has saved a lot of lives,” he said.

An ongoing police investigation

The Royal Canadian Mounted Police told the South China Morning Post last week that its investigation into alleged breaches at the Winnipeg lab was continuing, in the wake of the original 2019 referral by PHAC.

Corporal Julie Courchaine said she could provide “no further updates”.

Whether police are examining the virus shipment to Wuhan is not known. But the acting director general of the National Microbiology Laboratory, Dr Guillaume Poliquin, appeared to pour cold water on the suggestion at the same parliamentary committee hearing attended by Stewart.

Poliquin told MPs the shipment was made “in accordance with the lab’s standard operating procedures, and in compliance with the HPTA [Human Pathogens and Toxins Act] and the Dangerous Goods Act”.

Some of the questioning of Stewart and Poliquin reflected unsubstantiated claims about the shipment that have swirled on the internet, with MP Genuis asking whether the Wuhan institute undertook “gain of function” experiments on coronaviruses to make them more dangerous, and if PHAC allowed virus transfers to foreign labs where such experiments took place.

Poliquin said he could not answer, but “we have never transferred coronaviruses to the Wuhan Institute of Virology, therefore we have not assessed the question as structured”.

He told the MPs that the shipment was made after a request from the director of the Wuhan institute, who said the viruses would be “used for understanding pathophysiology, the nature of the infection as well as the development of antivirals”.

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Challenged by Conservative MP John Williamson over the “astonishing admission” the viruses were sent to China based on a letter from “a nation that has a history of theft, lies”, Poliquin said PHAC took an “extensive approach” to virus transfers. He called the Wuhan institute “an organisation dedicated to public health”.

Kobinger told the Post that when he was at the Winnipeg lab, protocols for sending viruses to China were no different to sending them to other countries.

“It doesn’t matter where it goes, it still requires several levels of approval. It includes the chief level, which was my position, but also the approval of the director general [of the National Microbiology Laboratory],” he said. “It had to involve informing the higher-ups.”

02:08

China says no evidence to suggest coronavirus virus came from Wuhan’s lab

China says no evidence to suggest coronavirus virus came from Wuhan’s lab

At the hearing, Poliquin defended China-Canada research transfers in general, saying China’s sharing of the genome sequencing of the virus that causes Covid-19 in January 2020 had allowed the Winnipeg lab to create its first test for the virus in just five days.

“This illustrates the essential nature of international cooperation as we continue to fight this pandemic,” he said.

A spokeswoman for Chong said he was not available for an interview, but he was still awaiting documents from Stewart about the “termination” of Qiu and Cheng.

“They were investigated. The investigation was completed. They are no longer part of the agency … I’m not at liberty to discuss it further,” said Stewart at the hearing.

Stewart added: “At this time I’m not aware of them being charged with any offence.”