Can epitope-focused vaccines select advantageous immune responses?

One of the great success stories of preventive medicine is the achievement of protection against many pathogens by the simple procedure of vaccination. The rationale behind vaccination is to generate a protective immune response and an expanded population of memory cells ready to encounter the infectious agent, which will then elicit a potent secondary immune response. However, the development of effective vaccines against many pathogens has, so far, been unsuccessful. Many vaccines in current use fail to direct the immune response towards the epitopes that will ensure optimal protection. In these circumstances, can vaccines be produced that focus the immune system in a calculated, epitope-specific manner?