COMPLEX SYSTEMS SEMINAR<br>Diseases and Drugs: Complexities in the Control of Contagion

Human populations and financial markets have one thing in common: they can both catch and spread infections. Indeed, the last few years have seen ‘pandemics’ in both: the first new human influenza virus of the century, as well as the biggest economic and financial crisis since the Great Depression. Such events make for a topical setting in which to study the dynamics and control of ‘contagion’, in different systems.

Here I will discuss recent and ongoing work in three different contexts.
In financial markets, contagion is like an unusual infection that gains in severity and infectiousness, as individuals become more apprehensive: hence the potentially catastrophic effect of market panics. The financial crisis has prompted fresh thinking about these systems; I will discuss recent work that borrows concepts from infectious disease dynamics, and theoretical ecology, to contribute to such thinking.

In the biological context, the dynamics of many human infectious diseases are profoundly shaped by a variety of factors. An important example is pathogen evolution for immune escape (as in the case of influenza virus), and in this context I will describe recent work on the potential impact of emerging vaccine technologies against influenza. Finally, I will discuss ongoing and future work in the role of economic conditions and the availability of essential medicines, in the global control of tuberculosis: a confluence of all three themes in the title of this talk.