What we know about how the coronavirus started, and why it matters
On Tuesday, the researchers announced their preliminary findings at a news conference, arguing that it was most likely that the virus spread to humans from bats through an intermediary animal and dismissed one of the more popular alternative theories: that it was the result of a leak from a Wuhan laboratory.
But the investigation still leaves many questions, and the findings are unlikely to sway critics who said the WHO team was too close to Chinese authorities for a fair investigation.
Here are some of the key questions about the origin of the novel coronavirus.
What is the main theory on the virus’s origin?
The coronavirus at the center of the global pandemic is known by the scientific name SARS-CoV-2.
Before it spread across the world, causing the potentially deadly illness known as covid-19, the closest relative was a virus known as SARS-CoV RaTG13 that was found in bats in caves in the Chinese province of Yunnan, more than 1,000 miles away from Wuhan.
Exactly how a relative of this virus spread to humans is unclear, but given the distance and the relative lack of human interaction with bats, it is possible it spread first to one or more intermediate animals, where it evolved into the virus SARS-CoV-2 that is more easily transmissible to humans.
To many scientists, this was the most likely scenario. “The virus is just like a virus we would expect to see in wild bat populations, similar viruses have jumped from nonhuman animals to animals in the past, so I see no reason to speculate about this any further,” Andrew Rambaut, a microbiologist at the University of Edinburgh, told Today’s WorldView last year.
Peter Ben Embarek, the Danish WHO food safety expert leading the international team, told reporters Tuesday that it was “most likely” the virus spread through an intermediate animal, but that more research was needed to find that animal.
Ben Embarek also added that though many of the first confirmed cases of covid-19 were found in the Huanan Seafood Market, a market that sold a variety of different animals, the coronavirus was also spreading outside the market in Wuhan, suggesting that it was not the original source of the outbreak.
Could it have leaked from a lab?
Some outside analysts have pointed to the presence of a major biological research center in Wuhan, the Wuhan Institute of Virology (WIV), and suggested that the virus could have be linked to its work.
Early in the pandemic, some suggested that the virus could even have been man-made as a potential weapon — an idea swiftly dismissed by most experts, who said there was no evidence to support the theory.
An alternative idea — that the virus leaked accidentally through normal research — has proved harder to dismiss. WIV was reported to be working on “gain of function” experiments, a controversial practice where scientists try to make viruses evolve so they can better understand them.
In January, the outgoing Trump administration released a State Department memo that called for more scrutiny of the work at the WIV but stopped short of saying it could confirm the lab leak theory.
Chinese officials and scientists linked to WIV have dismissed the idea, suggesting that the facility was not working on any close relatives of SARS-CoV-2, and some outside experts have said it is unlikely and motivated by political rivalry.
The WHO team had said it would consider the possibility and visited the WIV to talk to staff members. But on Tuesday, Ben Embarek said they had found it “unlikely,” and they would not recommend pursuing the theory further.
Are there other theories?
Some Chinese officials have pushed the idea that the virus came from outside their country, pointing to trace amounts of the virus that have been found on frozen food imported to China. The idea has met a mixed response from most outside experts, with critics suggesting that the evidence was weak.
On Tuesday, both Ben Embarek and a representative of the Chinese CDC, Liang Wannian, said the virus may have been transmitted through cold-chain food packaging. Ben Embarek noted that frozen food was sold at Huanan Seafood Market and said that, while unlikely, the virus could have taken a long path to Wuhan.
Why does the origin of the virus matter?
Given the enormous human toll of the virus, most researchers think finding as much accurate information about its early spread is imperative so that measures can be put in place to prevent it happening again.
For the theory considered most likely — that of zoonotic spread from bats to humans through an intermediate animal — this could have profound effects on human practices such as farming and wildlife exploitation. In the Netherlands, concern about the spread of the virus through farmed minks led to the mass cull of hundreds of minks.
Modern human life has led to a rise in the number of diseases that spread zoonotically between animals and humans. But there are also major implications for scientific research and international trade if theories related to a laboratory leak or cold-food chains could be confirmed.
