Susan Hahné is a senior epidemiologist in the National Immunisation Programme Department at the Centre for Epidemiology and Surveillance of Infectious Diseases of the National Institute for Public Health and the Environment (RIVM) in the Netherlands. Kaatje Bollaerts is the head of data science at P95 Belgium, a scientific service-providing company focused on pharmacovigilance and epidemiology related to vaccines and infectious diseases. Paddy Farrington is an emeritus professor of statistics at the Open University (OU), UK. Prior to joining the OU in 1998, he was a statistician at the Immunisation Division of the Communicable Disease Surveillance Centre in the UK for 11 years