Role of epidemiology in vaccine policy.

The application of epidemiological techniques is important at all stages in the development of a vaccination programme. Before licensing, the safety and efficacy of a new vaccine must be determined in carefully designed clinical trials. An epidemiological assessment of the disease is then needed in order to formulate an appropriate strategy for delivery of the vaccine. Once the vaccine has been introduced into routine use, continued evaluation, both of the vaccine and the programme, is required. Surveillance schemes should be established that are capable of detecting changes in vaccine safety and efficacy as well as monitoring coverage in the target population. Any important changes should be further evaluated by special studies. Postlicensing evaluation of vaccines and vaccination programmes has played an important role in shaping policy in the UK.