While in population health we would prefer that people did not become ill in the first place, this largely remains a remote goal, so achieving disease control through more effective treatments remains a core public health strategy. But prevention is still our ideal, and epidemiology underpins much of our work in this area. In particular, it is central to identifying causes of disease that we can change; it provides quantitative measures of relative and absolute risk that help direct preventive action; and it plays a major role in evaluating whether preventive programmes might actually work in practice. Additionally, what we might term the ‘epidemiological perspective’ is helpful in conceptualising both the practical and the ethical elements of prevention.

Disease prevention in public health

When we speak of prevention, we usually mean primary prevention, which aims to prevent disease from occurring in the first place, i.e. to reduce the incidence of disease. Vaccination against childhood infectious diseases is a good example of primary prevention, as is the use of sunscreen to prevent the development of skin cancer.

Figure 14.1 shows tuberculosis (TB) mortality over time in England and Wales. This is a disease that had all but disappeared from developed countries but is now re-emerging elsewhere as a worldwide scourge.