Recent research conducted into the genetic network analysis of the COVID-19 pandemic, done jointly by British and German experts, testified the variant of novel coronavirus that is closest to that discovered in bats was actually found mainly among cases from the US, rather than in Wuhan, Central China’s Hubei Province. 

…In reply to the question why the ancestral type of virus was not commonly seen in China and particularly in Wuhan, but instead the mutated type B virus, geneticist Peter Forster from the University of Cambridge, lead author of the study, told the Global Times that “type A isn’t fitting quite well with most locals’ immune systems in Wuhan” but has “become adapted to American and Australian immune systems.”

…But their study has evidence that the virus mutation rate is significantly faster outside China and the spread of the disease among humans likely occurred between September 13, 2019 to December 7, 2019. 

Ancestral type of COVID-19 virus mainly found in the US: study – Global Times

hmmm