'The genetic data was drawn from swabs taken from in and around the Huanan Seafood Wholesale Market starting in January 2020, shortly after the Chinese authorities had shut down the market because of suspicions that it was linked to the outbreak of a new virus. By then, the animals had been cleared out, but researchers swabbed walls, floors, metal cages and carts often used for transporting animal cages.'

https://www.nytimes.com/2023/03/16/science/covid-wuhan-market-raccoon-dogs-lab-leak.html