The new UK coronavirus mutations, explained

Health officials in the United Kingdom and around the world are worried about a new, seemingly more contagious variety of SARS-CoV-2 (the virus that causes Covid-19), which has emerged in the country and was announced over the weekend. The evidence that this new strain spreads more easily between people is not rock solid, but it’s concerning enough to have forced dramatic action.

Nations are already shutting down travel from the United Kingdom, where the new strain, known as B.1.1.7 (we’ll call it the UK variant, for simplicity’s sake), is rapidly...