– Blood samples unveiled this week show people in California, Oregon and Washington infected in December
– Further tests on blood taken in mid-to-late December and into early January found virus in six more states
– Italy, Brazil and France have all since found traces of the virus before China even acknowledged it existed
– Evidence has emerged in Spain and the UK suggesting that Covid-19 was around before testing was possible
– Claims the virus emerged in a market in Wuhan last winter have crumbled in the face of scientific evidence