In this bonus Christmas special, Cara chats to Professor Iain Buchan about his work using 'big data' to inform public health policy. Over the course of the COVID-19 pandemic, Iain and his team have provided analysis of large datasets to understand how the virus is spreading and how to contain it, as well as analysing the consequences of COVID-19 measures to plan for public health and economic recovery. This year, he also orchestrated the pilot testing events down at the Docks and in Sefton Park which helped provide information about the transmission of COVID-19. We discuss how his childhood experiences of living in North Liverpool inspired him to follow a career in Public Health, the importance of using big data for good and the impacts of the spread of misinformation about COVID-19, as well as what he has learnt over the course of the pandemic.