Vaccinations are one of the most successful public health measures. However, vaccinations are not without risks. An improved infrastructure is needed to facilitate the conduct of large clinical trials and/or phase IV studies. Vaccination registers and large linked database studies are examples of such structural improvements. A vaccination register pilot project carried out by the Swedish Institute of Infectious Disease Control (SIIDC) showed that parents with few exceptions gave consent to enrolling their children in the pilot register and that bar code labelling of vaccines is a reliable and practical manner in which to record vaccinations. Two EU projects with the aim to improve the information infrastructure have recently started. In the project Development of Vaccination Registers existing and planned immunisation registers are reviewed and a plan of action will be proposed. The aim of the project EUSAFEVAC is to improve vaccine safety through systematic reviews of the literature, to develop standard case definitions, to develop a model immunisation register and to improve reporting systems. SIIDC in collaboration with the Swedish National Board for Health and Welfare and the Medical Products Agency is exploring the feasibility of establishing a Swedish immunisation register and linked database information system.