Intransigent vs. volatile opinions in a kinetic epidemic model with imitation game dynamics.

The article focuses on developing a behavioural epidemiology model that integrates human opinion flexibility into the dynamics of infectious disease spread using a kinetic theory approach. Starting from a stochastic particle description, the authors derive a mesoscopic kinetic model and then a macroscopic system of nonlinear ordinary differential equations (ODEs) that extend a susceptible–infected–removed (SIR) framework by incorporating two susceptible groups distinguished by their social contact patterns: "normal" and "altered." The switching between these behaviours is governed by an imitation game dynamic influenced by individual degrees of opinion flexibility, representing personal propensity to change behaviour based on cost–benefit assessments. Numerical investigations reveal that varying opinion flexibility affects the timing, number, and magnitude of epidemic waves, with more volatile opinions leading to more frequent but lower peaks under high perceived infection risk, while under low perceived risk, flexibility mainly influences the cumulative incidence rather than epidemic peaks. The model's generality allows adaptation to other epidemiological contexts where behavioural heterogeneity and opinion dynamics are critical, such as vaccination uptake.