Coronavirus: Satellite traffic images may suggest virus hit Wuhan earlier

The BBC's John Sudworth in Beijing says there were limits on the data set used by researchers - for example, they could not always compare satellite images taken on the same day in consecutive years due to cloud cover in some of the photos. But if the infection was present - undetected perhaps - some people could have been leaving Wuhan and travelling abroad and that fits with some of the other evidence we have begun to see in other parts of the world suggesting early cases of Covid-19, our correspondent says. The mystery of early 'Covid' cases However it may be unfair to use the study as evidence of a cover-up or delay in China's response, because with a previously unknown illness taking root in a community it is quite possible that there was some undetected spread before it was noticed officially, our correspondent adds.