Experts Say Virus Origins Remain a Mystery, but Dismiss Lab Leak Theory

More than a year after the novel coronavirus emerged in China, it remains a mystery just where the virus came from. A team of international experts says a lot more work is needed to determine its origins. 

A World Health Organization-China joint press conference is held Tuesday in Wuhan, China, at the end of a WHO mission to investigate the origins of the coronavirus pandemic. (AP Photo/Ng Han Guan)

(CN) — A team of Chinese and international scientists convened by the World Health Organization to investigate the origins of the novel coronavirus said Tuesday it remains a mystery where the virus came from, but they dismissed as “extremely unlikely” the theory that it escaped from a laboratory in Wuhan.

A team of international experts arrived in China on Jan. 14 and have spent four weeks investigating the origins of the virus causing a pandemic that’s brought the world to its knees and killed more than 2.3 million people globally.

At a briefing at a hotel in Wuhan, the team of experts and their Chinese counterparts laid out their initial findings. They said they were no closer to knowing where the virus came from and that further research is needed in China and elsewhere to track down what animals are carrying the virus.

One conclusion the team agreed on was that it was “extremely unlikely” the virus somehow escaped from a high-tech virology laboratory in Wuhan that specializes in coronaviruses. That theory was pushed by the Trump administration and has led to much speculation.

The findings were hardly a surprise as scientists and the WHO have been saying for months that figuring out how the virus began infecting humans will be extremely complex and that the mystery may never be fully understood.

Shortly after the novel coronavirus was first identified circulating in the industrial Chinese city of Wuhan in December, scientists began worrying this new virus had spilled over from animals into humans just like the previous SARS and MERS coronaviruses had done and caused major outbreaks. Viruses found in wild animals can jump into other animals that are then consumed by humans. This remains the most likely hypothesis, the WHO team said.

“Our initial findings suggest that the introduction through an intermediary host species is the most likely pathway and one that will require more studies and more specific targeted research,” said Peter Ben Embarek, the lead WHO scientist on the team. 

The scientists said extensive sampling of wild and farmed animals in Hubei province, where Wuhan is located, and other Chinese provinces found no trace of the novel coronavirus, which has been classified as SARS-CoV-2.

Extensive sampling and clinical reviews of patient data from hospitals in Wuhan and the rest of Hubei also found no evidence the virus was circulating in humans prior to December, when the first cases were detected. Many of those first cases were connected with the Huanan Seafood Market in Wuhan where wild animals were sold for human consumption.

“There is no indication of the transmission of SARS-CoV-2 in the population in the period before December 2019,” said Liang Wannian, the head of an expert panel on Covid-19 at China’s National Health Commission. He spoke for the Chinese side of the team.

Embarek agreed and said there was no “evidence of large outbreaks that could be related to cases prior to December.”

This finding undermines allegations made by the Trump administration and others that China was somehow hiding the outbreak. There is, though, plenty of evidence that Chinese authorities took drastic measures to silence scientists and doctors warning about an alarming number of pneumonia-like cases in Wuhan. China officially notified the WHO about the outbreak on Dec. 31.

In Hubei, prior to December there was no uptick in pneumonia and influenza cases, no surge in deaths linked to respiratory problems and no surge in the purchase of cold and influenza medicine, Liang said. All this backs up an assumption that the virus was not widely circulating before December, he said. He said testing on blood samples from before December stored at blood banks also found no trace of antibodies to the virus, which would have indicated that people were being infected with the virus.

He said “it is considered unlikely that any substantial transmission of SARS-CoV-2 infection was occurring in Wuhan” during the two months before December.

The team of international and Chinese experts will issue a joint report in which they will agree on future steps to take in the research.

Throughout Tuesday’s briefing, Liang pushed the possibility that the virus may have originated outside of China and that it may have ended up reaching Wuhan through the importation of meat or animals.

“SARS-CoV-2 can persist in conditions found in frozen food, packaging and cold-chain products,” Liang said.

China has pointed to findings in Italy and elsewhere suggesting the virus was circulating as early as November, an indication that it might have begun infecting humans outside China first.

“This indicates the possibility of missed reported circulation in other regions,” Liang said, speaking through a translator. He suggested an “omission of reporting” or “underreporting of those kind of cases” may have occurred in other countries and needs to be further investigated.

Liang also said more research needs to be done into whether the virus may have spilled over into humans through species such as minks and cats, which have been shown to be easily infected by the virus. The virus was found in farmed mink populations in Europe, leading to the mass culling of minks in Denmark, the Netherlands and elsewhere. He said these species “could be a potential reservoir” for the virus and that they have been “massively under sampled” in the search for the virus’ origins.

While the WHO team agreed more research needs to be done in these areas of keen interest for Chinese scientists, Embarek laid more emphasis on the need to do more sampling of bat populations in China and in neighboring countries and to investigate Chinese farms that breed wild animals for human consumption. Bats and pangolins are considered likely species where the novel coronavirus came from before spilling over into an intermediary animal and then into humans. Both bats and pangolins carry coronaviruses similar to SARS-CoV-2.

Workers in protective suits walk through Wuhan, China, last April. (AP Photo/Ng Han Guan, File)

The team also said it remains possible that the virus jumped directly from a host species, such as a bat, into humans. However, Embarek said it was unlikely bats were the direct cause of the arrival virus in Wuhan because there aren’t bat populations in Wuhan or near it that carry coronaviruses similar to the SARS-CoV-2 variety.

The team used the outbreak at the Huanan Seafood Market as a starting point in their investigation, but there are lots of uncertainties surrounding it too.

Embarek said that while many early cases in December were linked to the Wuhan market, he said others were linked to other markets and other cases had no link to food markets.

“We know there was also spread among individuals who were not linked to this market, they were linked to other markets; they had no link to markets. So, the picture is not clear,” he said.

The team said they cannot say how the virus ended up at the Huanan Seafood Market, though they said it likely was carried there by an infected person, an infected animal or by way of imported frozen meat.

“How it was introduced and spread within the market is still unknown,” Embarek said. “As of today, we are working with the hypothesis that it could have been introduced by a person who was infected and then spread it to other persons in the market; that could be one of the traders, it could be a visitor. But it could also be through the introduction of the [meat] product.”

He said researchers need to do more to track down whether wild farmed animals sold at the market may have been the source of the virus.

“Some of these species are known species susceptible to these kinds of viruses,” he said. “These are providing clues.”

Marion Koopmans, a Dutch virologist on the team, said more work needs to be done to investigate the species sold at the Huanan Seafood Market.

“There were some animal species that have been confirmed to be susceptible, like rabbits, or that could be suspected to be susceptible, like ferret badger, bamboo rats,” Koopmans said. “It is an entry point for a trace-back investigation.”

She said researchers have found that animals sold at the market came from farms in regions “known to harbor bats with the closest related viruses” to the SARS-CoV-2 variety.

During its probe in Wuhan, the team of scientists also visited the Wuhan Institute of Virology, a government-backed laboratory that specializes in coronaviruses. The team’s visit to the laboratory carried huge political significance and intense media scrutiny after the Trump administration alleged it had evidence the lab was responsible for unleashing the virus on the world. The White House never made public any evidence it purportedly had. In turn, the Chinese government floated its own conspiracy theories suggesting the U.S. government was at fault for releasing the virus in China.

Embarek said the team of scientists took a “rational approach” in examining the lab leak hypothesis and, after visiting the lab and speaking with its staff, found that theory “extremely unlikely” and not worth pursuing further.

“The findings suggest that the laboratory incident hypothesis is extremely unlikely to explain the introduction of the virus into the human population,” he said.  

The Danish scientist continued, speaking in English. “Yes, accidents do happen, unfortunately. We have many examples from many countries in the world of past accident. So, of course, this is not impossible, it happens once in a while.”

But he said that hypothesis was ruled out in part because there is no evidence that the SARS-CoV-2 virus was “researched or identified or known.”

“There has been no publication, no reports of this virus, or another virus extremely linked, or closely linked to this, being worked with in any other laboratory in the world,” he said.

Embarek said the team reviewed the lab’s records, including audits, and examined the facility.

“It was very unlikely that anything could escape from such a place,” he said.

He said the team “had quite a substantial interaction with the staff there” and “a very long, frank, open discussion with the management and staff.” 

He said it was time to move on from conspiracy theories.

“Move away from the situation that has been around for the past year where all of us – and many around the world – have all come up with their personal views and feelings,” he said. “We wanted to move away from: ‘I think it is this way, or I believe it is this way.’”

However, one team member, Danish scientist Thea Koelsen Fischer, told reporters that the team cannot rule out further investigation into the possibility of a lab leak and new leads, according to the Associated Press. 

Liang said there are two ways a virus might come from a lab. One involves a virus “engineered by humans” and the other involves a lab accident.

He dismissed the idea that the virus was manufactured.

“This hypothesis has already been refuted by the whole scientific community around the world,” he said.

“But in terms of the leaking of the virus, there should be leaking of an existing or known virus; however, in all the laboratories in Wuhan there is no existing virus of SARS-CoV-2,” he added. “If there is no existence of this virus, there will be no way that this virus would be leaked.”


Courthouse News reporter Cain Burdeau is based in the European Union.

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