What can we predict about viral evolution and emergence?

Predicting the emergence of infectious diseases has been touted as one of the most important goals of biomedical science, with an array of funding schemes and research projects. However, evolutionary biology generally has a dim view of prediction, and there is a danger that erroneous predictions will mean a misuse of resources and undermine public confidence. Herein, I outline what can be realistically predicted about viral evolution and emergence, argue that any success in predicting what may emerge is likely to be limited, but that forecasting how viruses might evolve and spread following emergence is more tractable. I also emphasize that a properly grounded research program in disease prediction must involve a synthesis of ecological and genetic perspectives.

► Success in predicting what new viruses will emerge is likely to be limited. ► Predicting how viruses may evolve and spread following emergence is more tractable. ► Predicting the evolution of virulence requires both genotypic and phenotypic data. ► Compiling the phylodynamic patterns of existing viruses should be a priority. ► Meaningful prediction requires an important synthesis of genetics and ecology.