Creating a timeline that details the earliest COVID-19 cases in Wuhan

In a Perspective, Michael Worobey provides an overview of the crucial events that occurred between December 2019 and January 2020 in Wuhan, China, creating a timeline detailing the earliest cases of COVID-19, their connections to the Hunan Market where live animals were sold, and the events that led to SARS-CoV-2's formal identification as a novel virus. He draws on myriad sources – including the scientific literature and contemporary reporting in the press – to develop his timeline.

According to Worobey, most of the first cases of the virus were associated with the Hunan market, suggesting that zoonotic spillover at the live-animal market was the likely source of COVID-19. Unfortunately, no live mammal collected from Wuhan's live-animal market has been screened for SARS-CoV-2-related viruses and Hunan Market was closed and disinfected soon after the symptomatic cases began to rise. Despite this, Worobey notes that most of the early symptomatic cases were linked to Hunan Market, and specifically the western section where animals known to be susceptible to coronaviruses were caged.

"Although it may never be possible to recover related viruses from animals if they were not sampled at the time of emergence, conclusive evidence of a Huanan Market origin from infected wildlife may nonetheless be obtainable through analysis of spatial patterns of early cases and from additional genomic data, including SARS-CoV-2 positive samples from Hunan Market, as well as through integration of additional epidemiologic data," write the authors. "Preventing future pandemics depends on this effort."