Central to infectious disease control is tracking the spread of a pathogen through the population. In Cambridge, UK, researchers are looking at genetic mutations in samples from Covid-19 patients to rapidly investigate how and where hospital transmissions are occurring. Dr Estée Török tells Nicola Davis what this real-time pathological detective work can reveal about the origins of an outbreak. Help support our independent journalism at <a href="https://www.theguardian.com/sciencepod">theguardian.com/sciencepod</a>
