Under government pressure, Chinese scientists have retracted studies and withheld or deleted data. The censorship has stymied efforts to understand the virus.
Scientists from the Chinese C.D.C. confirmed that DNA from raccoon dogs and other animals susceptible to the coronavirus was found at the market in early 2020.
As China casts aside many Covid rules, it is also playing down the threat of the virus. The move could help ease the burden on hospitals but comes with its own risks.