Pigs didn’t Fly, but Swine Flu

In 2009, the world experienced the first influenza pandemic for thirty years. Identified in Mexico in March, the novel swine flu quickly spread across the globe and was declared a public health emergency by the World Health Organization at the end of April. In the UK, the epidemic differed from regular flu epidemics in that it occurred during the summer rather than the winter. Using a relatively simple system of differential equations, we try to understand how changes in human behaviour and social mixing influenced the epidemic.