Our recent research on the role of individuals who do not comply with public health safety measures in epidemic context has been published in the Proceedings of the Royal Society A.
The study shows how risky behaviours in case of pandemic and epidemic settings can undermine public health interventions. This is particularly relevant in urban environments because of their high population density and complex social interactions. In this study, we employ detailed contact networks, built using a data-driven approach, to examine the impact of non-compliant individuals on epidemic dynamics in three major Italian cities: Torino, Milano and Palermo. We use a heterogeneous extension of the susceptible–infected–recovered (SIR) model that distinguishes between ordinary and non-compliant individuals, who are more infectious and/or more susceptible. By combining electoral data with recent findings on vaccine hesitancy, we obtain spatially heterogeneous distributions of non-compliance. Epidemic simulations demonstrate that even a small proportion of non-compliant individuals in the population can substantially increase the number of infections and accelerate the timing of their peak. Furthermore, the impact of non-compliance is greatest when disease transmission rates are moderate. Including the heterogeneous, data-driven distribution of non-compliance in the simulation results in infection hotspots forming with varying intensity according to the disease transmission rate. Overall, these findings emphasize the importance of monitoring behavioural compliance and tailoring public health interventions to address localized risks.
The full paper is accessible online as gold open-access at: https://doi.org/10.1098/rspa.2025.0511.
You can cite the paper as:
F. Mazza, M. Brambilla, C. Piccardi, and F. Pierri, “A data-driven analysis of the impact of non-compliant individuals on epidemic diffusion in urban settings,” Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, vol. 481, no. 2324, Oct. 2025. https://doi.org/10.1098/rspa.2025.0511
