What are the prospects for coronavirus vaccines and the challenges involved in rolling them out around the world in 2021? The Economist's health policy editor explains what regulatory and logistical obstacles must be overcome as vaccines move from the laboratory to the clinic. And the CEO of Gavi, the vaccine alliance, explores how political and economic factors will govern vaccine distribution. Tom Standage hosts.   Subscribe to The Economist for full access to print, digital and audio editions: www.economist.com/podcastoffer    See acast.com/privacy for privacy and opt-out information.