On the design of national vaccination programmes.

The decision to include a vaccine in a national vaccination programme (or not) is usually evidence-based. Thereby, it is essential that the target disease causes a high burden of disease and that vaccination reduces this burden considerably. Furthermore, vaccination should be considered to be cost-effective by a government. Vaccines are usually administered according to standard vaccination schedules, which have been established on historical grounds. We argue and demonstrate with examples (meningococci C, Haemophilus influenzae, pneumococci and Bordetella pertussis) that adaptation of these standard vaccination schedules can be cost-saving and lead to better protection. To facilitate the improvement of vaccination programmes, a better understanding of protective immune responses (correlates of protection) and immunologic memory are required.