How high is a high risk? Prioritising high-risk individuals in an influenza pandemic

Pandemic contingency plans frequently define priority groups that are given preferential access to influenza vaccine. One of the most commonly named groups for prioritisation is that of high-risk individuals. However, current models of categorisation are unsatisfactory in a number of ways. It will be argued that existing vaccination strategies fail to adequately define what kind of risks are being considered and how, as well as on the basis of which information, these risks are calculated. Moreover, it will be suggested that existing vaccination strategies fail to specify of what magnitude a risk has to be, in order to be categorised as 'high'. Finally, it shall be argued that a mere focus on the size of a risk factor may lead policy makers to overlook underlying concerns of distributive justice.