A genetic study of samples from more than 7,500 people infected with Covid-19 suggests the new coronavirus spread quickly around the world after it emerged in China sometime between October and December last year, scientists said on Wednesday.

Scientists at University College London’s Genetics Institute found almost 200 recurrent genetic mutations of the new coronavirus - SARS-CoV-2 - which the UCL researchers said showed how it is adapting to its human hosts as it spreads.