Dissecting the early COVID-19 cases in Wuhan

Some key questions lie at the heart of investigations into the origin of the COVID-19 pandemic, including what is known about the earliest COVID-19 cases in Wuhan, China, and what can be learned from them? Despite assertions to the contrary (1), it is now clear that live mammals susceptible to coronaviruses, including raccoon dogs (Nyctereutes procyonoides), were sold at Huanan Market and three other live-animal markets in Wuhan before the pandemic (2, 3). Severe acute respiratory syndrome–related coronaviruses (SARSr-CoVs) were found in raccoon dogs during the SARS outbreak, which was facilitated by animal-to-human contact in live-animal markets in China. However, because of the early public health focus on Huanan Market, it remains unclear whether the apparent preponderance of hospitalized COVID-19 cases associated with this market was truly reflective of the initial outbreak. Answering these questions requires resolving several crucial events that took place in December 2019 and early January 2020.