Competing activation mechanisms in epidemics on networks

Area of Science:

• Network Science
• Epidemiology
• Complex Systems

Background:

• Traditional understanding attributed epidemic dominance to network hubs.
• Recent studies highlight the significance of the network's innermost core for epidemic sustainment.
• The interplay between network structure and epidemic dynamics is complex.

Purpose of the Study:

• To investigate how different epidemic process types are sustained in heterogeneous networks.
• To elucidate the distinct roles of network hubs and the core in epidemic spreading.
• To analyze the impact of network properties, such as degree distribution and correlations, on epidemic dynamics.

Main Methods:

• Theoretical analysis of epidemic spreading mechanisms in complex networks.
• Modeling of epidemic processes with transient and steady states.
• Examination of network topology, including degree distribution and topological correlations.

Main Results:

• Epidemics with transient states are primarily sustained by the network's innermost core.
• Steady-state epidemics exhibit dual mechanisms: either hubs sustain activity independently, or the core becomes globally active.
• In uncorrelated networks, the dominant mechanism depends on the decay exponent of the degree distribution ( > 5/2 for hub dominance, <= 5/2 for core dominance).

Conclusions:

• The mechanism driving epidemic spreading is contingent on the epidemic's state (transient vs. steady).
• Network hubs and the core play context-dependent roles in epidemic sustainment.
• Topological correlations in real-world networks can modify these identified spreading mechanisms.