Better understanding of patterns and processes underlying cross-immunity is needed to better understand future dynamics and burden of important diseases. Simple dynamical models of cross-immunity can often be classified as either history-based (classifying individuals by history of infections), or status-based (classifying individuals by what strains they are currently effectively immune to). There is a very strong analogy between these classifications and those of “leaky” and “polarized” vaccine models.

I will discuss how the mechanism of immune-boosting – that is, enhanced immune protection following an unsuccessful infection challenge – can bridge between these two paradigms. Our group has shown that different conceptual assumptions can lead both to different estimates of vaccine effectiveness, and different predictions about future dynamics.