The limits of prevention.

Recent years have been marked by unprecedented accomplishments in preventing disease and reducing mortality. More gains can be expected, but there are limits. The forces shaping the nature and potential of prevention programs can be characterized as points falling along a spectrum ranging from the purely scientific to the purely social. This paper focuses on four elements of that spectrum, discussing some of the limitations to prevention that are presented by biological, technical, ethical, and economic factors. The author concludes with an essentially optimistic perspective on the prospects, special opportunities, and imperatives inherent in each of the categories of limitations discussed.