The origin story of Covid-19 remains a mystery mired in contentious geopolitical debate. But a research paper that languished in publishing limbo for a year and a half contains meticulously collected data and photographic evidence supporting scientists’ initial hypothesis—that the outbreak stemmed from infected wild animals—which prevailed until speculation that SARS-CoV-2 escaped from a nearby lab gained traction. 

According to the report, which was published in June in the online journal Scientific Reports, minks, civets, raccoon dogs, and other mammals known to harbor coronaviruses were sold in plain sight for years in shops across the city, including the now infamous Huanan wet market, to which many of the earliest Covid cases were traced. The data in the report was collected over 30 months by Xiao Xiao, a virologist whose roles straddled epidemiology and animal research at the government-funded Key Laboratory of Southwest China Wildlife Resources Conservation and at Hubei University of Traditional Chinese Medicine.