Understanding the dynamics of infectious-disease transmission demands a holistic approach, yet today's models largely ignore how epidemics change individual behaviour. The best epidemic modelling techniques are quite sophisticated in the way that they incorporate the subtleties of human contact. Yet there is more to be done, notably by taking account of behavioural responses to epidemics. Most models are based on a static social contact network, but in fact people's responses can shift as an epidemic progresses. Visit http://tinyurl.com/2gw7up to download previous Connections essays.