The first study concluded that the Huanan market was indeed the epicenter of the virus.
Worobey and his colleagues came to their first conclusion by estimating the location of 156 COVID-19 cases in Wuhan in December 2019, then mapping the spread using a social media case-reporting app called Weibo.
For their second study, the researchers created an evolutionary family tree of the viruses sampled during the first few weeks of the pandemic, finding a split into two major branches.
The findings released Saturday bolster the conclusions of an earlier report from Worobey published in the prestigious academic journal Science.