2.4.2 Temporal network vulnerability and resilience
The outgoing contact chain (OCC) quantifies the number of ‘downstream’ premises that could potentially acquire infection from the indexpremise through outgoing animal movements, adhering to the chronological order of the movements (FIELDING et al., 2019; PAYEN; TABOURIER; LATAPY, 2019).
We use this approach to build the OCC model, which can be viewed as a simplified representation a SI (susceptible- infected) model structure if every between-premise movement results in transmission; a potential outbreak can be seeded at a given time t0 in each node in turn, and the resulting OCC can be considered the outbreak size.
By simulating the OCC across all possible seed nodes, we generated a distribution of the network’s OCC sizes. We then calculated the average OCC and 95% CI across all premises using the entire period of study. We quantified the vulnerability of OCCs to the removal of 10, 250, 500, 1000 and 1500 nodes, with the order in which nodes were removed based on network metrics in descending order (Degree, Betweenness, Closeness, PageRank, OCC size), and also selecting Random-nodes. We then analyzed the changes in the mean OCC size over time.