Velocity and hierarchical spread of epidemic outbreaks in scale-free networks

TL;DR

This paper investigates how the structure of scale-free networks influences epidemic spread, revealing rapid, hierarchical propagation driven by highly connected hubs, which informs containment strategies.

Contribution

It demonstrates that epidemic spread in scale-free networks occurs almost instantaneously and follows a hierarchical pattern based on node connectivity.

Findings

Epidemics spread rapidly in scale-free networks due to degree fluctuations.

Hierarchical cascade of infection from hubs to smaller degree nodes.

Implications for designing effective containment strategies.

Abstract

We study the effect of the connectivity pattern of complex networks on the propagation dynamics of epidemics. The growth time scale of outbreaks is inversely proportional to the network degree fluctuations, signaling that epidemics spread almost instantaneously in networks with scale-free degree distributions. This feature is associated with an epidemic propagation that follows a precise hierarchical dynamics. Once the highly connected hubs are reached, the infection pervades the network in a progressive cascade across smaller degree classes. The present results are relevant for the development of adaptive containment strategies.