As the northern hemisphere heads towards its second winter battling covid-19, epidemiologist Professor Dame Anne Johnson explains the risk of a surge in flu cases and how to avoid a double pandemic. Also, a decline in mental health was one of the unforeseen consequences of the coronavirus crisis. Dr Wendy Suzuki, a neuroscientist, advises how to turn everyday anxiety into a positive emotion. And, a new form of sea defence is part natural, part artificial. Kenneth Cukier hosts. For full access to The Economist’s print, digital and audio editions subscribe at economist.com/podcastoffer and sign up for our new weekly science newsletter at economist.com/simplyscience. See acast.com/privacy for privacy and opt-out information.