To study a system, mathematicians begin by identifying its most crucial elements, and try to describe them in simple mathematical terms. As Phil Wilson tells us, this simplification is the essence of mathematical modelling.
Ever since the thalidomide tragedy, governments have realised the importance of a strict licensing regime for new drugs. Medical statistician Robert Hemmings explains how his work for the Medicines Control Agency helps to safeguard the health of the nation.
Over the past one hundred years, mathematics has been used to understand and predict the spread of diseases, relating important public-health questions to basic infection parameters. Matthew Keeling describes some of the mathematical developments that have improved our understanding and predictive ability.