Vaccines and Variants is a great title for a fun new geeky game but a very bad combination for public health. New variants of the virus which causes Covid 19 are turning up in countries all over the world. Can the vaccines we have keep up with them, or do years of booster jabs await us? Tim Harford answers these questions with this week's panel of guests: Professor Peter Hotez of the Baylor College of Medicine, Professor Emma Thomson of the University of Glasgow and Dr Adam Kucharski of the London School of Hygiene and Tropical Medicine. Producer: Sandra Kanthal Listener questions can be sent to: vaccine@bbc.co.uk