The 25-year-old visited a Milan hospital complaining of a sore throat and skin lesions in November 2019 - a month before Covid-19 would be identified in the Chinese city of Wuhan. Research published in January this year found that a skin sample left by the woman yielded traces of the coronavirus when it was tested more than six months later. Scientists say the woman's case suggests that the virus was circulating in China and elsewhere long before the first cluster exploded at Wuhan's Huanan seafood market in December 2019, and further study of her case could help to determine just how long. The only problem is that no one knows the woman's identity.