CoronavirusChina Probe: SARS-CoV-2 Jump from Go-Between Host Most Likely Scenario

By Lisa Schnirring

Representatives from China and an international joint mission team led by the World Health Organization (WHO) Monday in Wuhan detailed the results of a 2-week probe into the zoonotic source of the outbreaks, which didn’t reveal a definitive source but did shed new light on the events.

At the nearly 3-hour briefing, officials laid out four main theories, some of them less likely possibilities. The 10-person joint mission team has been in China since Jan 14 and followed investigation terms that a WHO advance team fleshed out with the country over the summer.

The team was quarantined for the first part of its stay, followed by 12 days of field work that took them to locations in Wuhan, such as hospitals, the seafood market initially thought to have triggered the first outbreaks, and the Wuhan Institute of Virology (WIV).

Intermediary Host Most Likely Pathway
At the briefing, Peter Ben Embarek, PhD, who led the WHO team, said introduction through an intermediary host species is the most likely of the four scenarios, according to CNN. Confirmation will require more studies and targeted research.

Ben Embarek also said transmission through the sale of frozen products is possible. China has pushed the cold-chain packaging theory and has said the virus on imported frozen foods has been one likely source of small flare-ups that followed the country’s first surge. However, over the past months, the WHO has said there’s no evidence that people can contract the virus from food or food packaging.

The group’s seafood market tour found that vendors were selling frozen animal products, including farmed wild animals, and further studies into the supply chain might be useful, he said, according to Reuters. “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,” Ben Embarek said.

The two other possibilities, a direct spillover from the animal reservoir and a lab-incident possibility, are less likely, Ben Embarek said. The spillover is still considered a topic of further study, though, while investigators assessed the lab-incident possibility as the least likely cause of SARS-CoV-2 jump to humans due to safety protocols that are in place at the facility.

Ben Embarek said the team was able to question lab scientists and administrators about coronavirus work that was done at the lab.