Vaccines and their impact on the control of disease

Disease control exerts evolutionary pressures that can lead to the evolutio n of resistance. This has been seen in a spectacular fashion in the evoluti on of resistance to antibiotics, anti-virals and anti-parasitics. Despite i ntense (and often successful) attempts to control infectious diseases throu gh vaccination, there is still rather little evidence of the emergence of s trains of pathogen resistant to vaccines. This chapter asks why this should be so and what are the exceptions indicating that the evolution of vaccine resistance, though currently rare, is a possibility that should be planned for.