Host vaccination has long been used to combat a variety of infectious diseases, and implementation is rapidly expanding beyond human disease systems. However, the impact of vaccines on infectious disease ecology and evolution is rarely investigated. Furthermore, a major limitation of studies of efficacy control measures is that they are conducted under artificially homogeneous conditions. As such, the ability to predict how effective control measures will be under heterogeneous conditions is limited. Here, we examine heterogeneity in susceptibility to infection in vaccinated and unvaccinated hosts using a model system of infectious hematopoietic necrosis virus (IHNV) in rainbow trout.
Results/Conclusions
Through the use of modified dose-response models, we find that unvaccinated fish have a heterogeneous response to infection, which would have resulted in overestimates of infection in conventional models. Vaccination changes the susceptibility distribution of hosts, resulting in a more heterogeneous population with lower overall infection. These findings provide validation of methodology that can help to reduce biases in predictions of vaccine efficacy in natural settings. More broadly, the results can provide insight into how vaccination shapes population susceptibility and thereby may influence eco-evolutionary dynamics of hosts in multi-pathogen environments.