The initial spread of the coronavirus among people most likely originated from an animal and not from a Chinese lab, World Health Organization-led scientists told a news conference on Tuesday.
The team of international and Chinese scientists told a highly anticipated press briefing from Wuhan, China, that they could not conclude whether the virus has jumped directly from an animal to humans or through an intermediary host such as a bamboo rat or pangolin, but it was "extremely unlikely" that it spread from an accident in a Chinese lab.
They spoke while finishing a nearly four-week visit that began on January 14 and included stops at hospitals, research facilities and the Huanan Seafood Market in Wuhan, a so-called 'wet market' that sells frozen seafood, live domesticated wildlife such as rabbits and bamboo rats, and other food, and is where a cluster of COVID-19 cases was first detected in late December 2019.
China agreed to the closely watched visit of foreigners seeking the origins of the coronavirus only after months of negotiation and on the condition that it would be run as a joint investigation between 13 international scientists and 17 Chinese scientists.
The World Health Assembly, WHO's governing body, also applied pressure by calling for an investigation last year. Since it began, the pandemic has infected 106 million people and killed 2.3 million people worldwide.
"There were some animal species that have been confirmed as susceptible, like rabbits," Dutch virologist Marion Koopmans told the webcast press briefing, suggesting the next logical step would be to conduct more investigation of Chinese farms. "Some of the trace back was in farms or in traders in regions that are known to harbor bats, where the closest-related virus is."
'Natural reservoir' in focus
The leader of the scientific team, Peter Ben Embarek, a Danish scientist and WHO expert on food safety and animal diseases, confirmed the indirect jump from animals to humans was the probable route for the virus.
“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," Embarek told the news conference.
“All the work that has been done on the virus and trying to identify its origin continue to point toward a natural reservoir,” he said, emphasizing the likelihood that the virus was transmitted from a bat to humans using another animal as an intermediary.
Frozen products sold in China might have contained the virus, he allowed, but he also shot down speculation it initially leaked from some of the virus samples that have been collected by the Wuhan Institute of Virology — a groundless theory promoted by former U.S. President Donald Trump and his administration.
“The findings suggest that the laboratory incidents hypothesis is extremely unlikely to explain the introduction of the virus to the human population,” Embarek said, adding that such accidents are rare and the lab's security likely would have prevented any such release.
He dismissed the idea of spending any time studying the hypothesis further, particularly since the lab reported no such virus in its midst before the pandemic began.
The lead Chinese scientist, Liang Wannian, echoed that assertion. However, another Danish scientist, Thea Koelsen Fischer, a public health expert and specialist in virus epidemics, said the team could not rule out more investigation into the matter.
Liang said the virus appeared to have spread in Wuhan apart from the seafood market; the team said there was no evidence it was widespread before then. He also said there was "no indication there were clusters before what we saw happen in the later part of December in Wuhan."
Beijing has sought to control international research into the origins of the coronavirus, and Chinese-controlled media have suggested it may have originated in Europe. Several members of the WHO-led team of international scientists spoke at the press briefing in conjunction with the Chinese scientists.
China's government also has been scrutinized for how forthcoming it was in its initial reporting in light of the former Trump administration's accusations that China was engaged in obstruction.