A man in Colorado has become the first known US case of the newly identified strain of Covid-19 circulating in the UK. The new variant is thought to be more contagious than other, established variants and has prompted some countries to restrict travel from the UK.

The Colorado man who contracted the new variant, called B.1.1.7, is in his 20s, and had no travel history, according to the state’s health department. In a statement, Governor Jared Polis said that health officials are conducting an investigation into how the man might have contracted the virus, while he recovers in isolation.