The coronavirus is unlikely to have leaked from a Chinese lab and is more likely to have jumped to humans from an animal, a World Health Organization team has concluded, an expert said on Tuesday as the group wrapped up a visit to explore the origins of the virus.
The WHO team that visited central China’s city of Wuhan, where the first cases of COVID-19 were reported in December 2019, is considering several theories on how the disease first ended up in humans, leading to a pandemic that has now killed more than 2.3 million people worldwide.
“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,” WHO food safety and animal diseases expert Peter Ben Embarek, who led the team, said on Tuesday.
He said that work to identify the origins of the coronavirus points to a natural reservoir in bats, but the absence of bats in the Wuhan area dimmed the likelihood of direct transmission.
Liang Wannian, head of the China side of the joint mission, said animal transmission remained the likely route, but “the reservoir hosts remain to be identified.”
Investigators were also looking for Chinese blood samples that could indicate that the virus was circulating earlier than first thought, Embarek said. “And the conclusion was we did not find evidence of large outbreaks that could be related to cases of COVID-19 prior to December 2019 in Wuhan or elsewhere.”
“However, the findings suggest that the laboratory incidents hypothesis is extremely unlikely to explain the introduction of the virus to the human population” and will not be suggested as an avenue of future study, he said.
The WHO team, which includes experts from 10 countries, arrived in Wuhan from Singapore on January 14. After two weeks of quarantine, it visited key sites including the Huanan seafood market, the location of the first known cluster of infections, as well as the Wuhan Institute of Virology, which has been involved in coronavirus research.
Transmission through the trade in frozen products was also a possibility, Embarek said. China has repeatedly announced finding the coronavirus traces on imported food packaging.
“We know the virus can survive in conditions that are found in these cold, frozen environments, but we don’t really understand if the virus can transmit to humans” or under which conditions, he told the briefing.
Embarek said it would be worthwhile to explore whether a frozen wild animal in a market setting with the right conditions could be conducive to rapid spread of the virus. However, Embarek said the team’s nearly monthlong investigation in Wuhan had not dramatically changed the picture of the outbreak.
Infectious disease expert Dominic Dwyer, said it would probably take years to fully understand the origins of COVID-19.