The ghost of infections past: Accounting for heterogeneity in individual infection history improves accuracy in epidemic forecasting

Variation in infection history is an important but often underappreciated driver of individual variability in responses to infections. Such individual heterogeneity in immune responses, stemming from variable previous exposure to pathogens, subsequently influences epidemiological outcomes. By comparing research on innate immune priming in invertebrates, which lack adaptive immune memory but demonstrate enhanced responses to re-infections, to patterns seen in vertebrates, this Essay reveals broad implications for disease dynamics. Insights from mathematical modelling and experimental data highlight the critical need to integrate evolutionary disease ecology into public health initiatives to better predict and manage infectious diseases.