World Health Organization (WHO) investigators have ended their four-week trip to Wuhan, China, seeking the roots of the COVID-19 pandemic and have given some insights into what they discovered.
After staying tight-lipped during their visit, investigators say they’ve determined:
- The coronavirus that causes COVID-19 likely originated in bats from southern China or nearby parts of Southeast Asia.
- The virus jumped to people through an intermediate animal, although it is unclear which type of animal. Farmed wildlife animals are considered a likely bridge to humans.
- Although the Huanan market was the early focal point of the outbreak, 13 strains of the COVID-19 virus were circulating in Wuhan where COVID-19 appeared in December 2019, indicating that the virus was widespread in the city.
“The possible path from whatever original animal species all the way through to the Huanan market could have taken a very long and convoluted path involving also movements across borders,” team leader Peter Ben Embarek said during a nearly three-hour media briefing in Wuhan on February 9.
The investigators worked with their Chinese counterparts to review data collected around the time the virus was announced at the end of 2019. They also met with the first recorded COVID-19 patient, a man in his 40s with no history of traveling.
Chinese authorities provided a variety of data, but investigators ran into obstacles when they asked for anonymous patient data on 174 cases from the early stages of the outbreak in Wuhan. The team received only a summary of the data, according Dominic Dwyer, an Australian infectious disease expert on the team.
Dwyer told Australia’s SBS News that reviewing raw data is standard practice in investigating a disease outbreak. Dwyer said it’s unclear why Chinese authorities withheld it.
The Chinese government worked to shut down discussion of an outbreak soon after it emerged, including gagging whistleblower Li Wenliang, the Wuhan doctor who was among the pandemic’s earliest victims.
During the past year, China has offered a variety of unsubstantiated theories for the source of the virus, most of them shifting blame away from the government, including the most recent claim that the virus entered the Huanan wet market through imported frozen food.
Embarek has said it’s unclear whether a virus on frozen foods could infect people.
According to zoologist Peter Daszak, the Huanan market showed clear evidence of vendors selling live animals, which could have caused human infection. Daszak is president of the Eco Health Alliance, a nonprofit dedicated to preventing pandemics.
“You’ve got animals coming into the market which are susceptible,” Daszak told The New York Times. “Some of these are coming from places where we know the nearest relatives of the virus are found. So, there’s the real red flag. … What we now have are a clear link and a potential pathway.”
Despite that, Chinese researchers reported no evidence of COVID-19 in the 30,000 animals they sampled in the market, said Marion Koopmans, a Dutch virologist who was part of the investigative team.
“Those could just as easily have revealed the smoking gun,” she told a WHO news conference on February 12. “It does provide some leads for next steps in the study.”
Some of the animals in the market, for example, came from areas where they could have been infected by bats.
“This, to me, is a critical finding,” Daszak said.
Embarek said the WHO team hopes to return to Wuhan to do more research.
“We have a much better understanding on what happened in the market and the role of the market in December,” he told the WHO news conference. “We still are far away from understanding the origin and identifying the animal species or the pathway through which the virus could have entered humans.”