Abstract

In this talk, I will present the research of my PhD on vaccine escape, working with Julia Gog. Using compartmental SIR -style models with imperfect vaccination, we allow for the probability of immune escape to differ in vaccinated and unvaccinated hosts. As the relative contribution to selection in these different hosts varies, the overall effect of vaccination on the antigenic escape pressure at the population level changes. If vaccinated hosts do not contribute much more than unvaccinated hosts to the escape pressure, then increasing vaccination always reduces the overall escape pressure. In contrast, if vaccinated hosts contribute significantly more than unvaccinated hosts to the population level escape pressure, then the escape pressure is maximised for intermediate vaccination levels. This work is part of a recent preprint, but I will also present further extensions. Reinfections may also contribute differently to escape, and their presence changes the shape of the escape pressure as a function of the vaccination coverage. We also extend our model to include population heterogeneity. The presence of immunocompromised hosts, who contribute more to immune escape, can lead to new overall patterns in the escape pressure. This work highlights the potential value of understanding better how the contribution to antigenic escape pressure depends on individual host immunity.