Boundary Degree as a Node-level Feature for Epidemic Scenario Identification in Agent-based Cascade Simulations

2026-06-28

AI Summary

This study addresses the critical challenge of identifying plausible epidemic scenarios from disease transmission cascades. It introduces, for the first time, “boundary degree”—defined as the number of uninfected neighbors of an infected node in a contact network—as an explicit node feature for scenario identification, complemented by edge features and evaluated through systematic ablation experiments. Leveraging agent-based simulations on real-world social contact networks, graph neural representation learning, and theoretical distinguishability analysis, the work demonstrates that certain epidemic scenarios become indistinguishable in the absence of boundary or edge information. Incorporating boundary degree alone improves identification accuracy by 19%, and it exhibits complementary value with edge features, underscoring the importance of tracking contacts involving non-infected individuals for accurate scenario inference.

Abstract

Characterizing the scenario underlying an epidemic from its disease cascade is an important task in simulation analytics. We propose boundary degree, the count of an infected node's contacts in the underlying contact network that were not infected, as a per-node cascade feature for this task. Through systematic ablation on realistic social contact networks of Tennessee and Virginia, we show that boundary degree alone improves scenario identification accuracy by 19%. Edge features, whose importance was observed empirically by prior work, consistently improve accuracy across all settings; we provide theoretical grounding for this observation. These effects are complementary. We prove that certain epidemic scenarios are indistinguishable without boundary or edge information. Prior feature engineering approaches included aggregate boundary statistics, but these were not among the top-ranked feature groups; the per-node representation we propose reveals their importance clearly. Our results suggest that contact tracing applications should track contacts with non-infected individuals, not only transmissions.

Problem

• epidemic scenario identification
• disease cascade
• contact network
• node-level feature
• simulation analytics

Innovation

• boundary degree
• epidemic scenario identification
• agent-based simulation
• contact network
• node-level feature