New analysis of samples taken at a Wuhan market in the early days of the pandemic suggests that infected animals were present, including raccoon dogs, according to a report in The Atlantic magazine.
The findings support the theory that COVID-19 jumped from animals to humans, but researchers caution that it is not conclusive because the chain of events for how an animal got infected cannot be proven.
China has been criticized for not allowing an independent investigation into the origins of the virus.
A classified report to Congress by the Department of Energy concluded with low confidence that COVID-19 leaked from a Wuhan lab, according to sources with direct knowledge.
The FBI also believes the lab may be the source, although there is disagreement among federal agencies.
Congress has unanimously approved a bill calling on President Biden to declassify information related to the origins of COVID-19, but he has yet to sign it.