This animation explains the ways in which diseases spread in the population and how this is modelled for health economical decision making, such as cost effectiveness of a vaccination programme. The long and very formal title of the project carrying out this work is Mathematical & Economic Modelling for Vaccination and Immunisation Evaluation, or MEMVIE for short. MEMVIE is also a leader in public involvement work in mathematical and health economic modelling. This research is funded by the Nati