The new strain of coronavirus that has cancelled Christmas

Guardian health editor Sarah Boseley looks at the fast-spreading Covid variant that has prompted the prime minister to put London, the south east and the east of England into tier 4 and more than 40 countries to ban UK arrivals because of concerns about the spread. Help support our independent journalism at <a href="https://www.theguardian.com/infocus">theguardian.com/infocus</a>