The expected impact of new vaccines and vaccination policies.

Aim The purpose of this paper is to outline the potential of newly available vaccines and highlight the evolution of tools required for correctly assessing the impact of immunisation policies. Subjects and methods We review an entire range of critical factors in the evaluation of the impact of new vaccines and vaccinations, including herd immunity, immunological memory, epidemiology and indirect effects of immunisation on vaccine-preventable diseases and illnesses. Results The impact of newer vaccines on public health has become as complex as it is promising: the benefits of vaccinating according to aged-based rather than at-risk-based recommendations (e.g. influenza vaccine); societal benefits going beyond the mere avoidance of death and hospitalisation (e.g. rotavirus vaccine); prevention of associated pathological states, of many confirmatory tests following a positive result of screening and psychological distress (e.g. human papillomavirus vaccine); or reduction of serious sequelae and associated chronic suffering (e.g. zoster vaccine). Conclusion The changing context of vaccinology offers new challenges for research methods and orientations. Clearly, we must shift from the concept of prevention of disease to that of prevention of illness. Developing tools for the precise measurement of these phenomena involves multidisciplinary co-operation in the development of dynamic models; at the same time, we must improve our communication skills for explaining complex issues to the larger public.