1. Markus Schwehm and Martin Eichner free  traced, quarantine
Stochastic Simulation of Epidemics on Large Contact Networks
Markus Schwehm and Martin Eichner
Department of Medical Biometry, University of Tübingen, Germany
Contact Network
Event Model
public interface Network {
public int[] getContacts(int node);
public int getSize();
public double getAverageConnectivity();
public void report(); }
Network Interface
FI
free  isolated
FI
free  isolated
FT,Q
free  traced, quarantine
Abstract Network
ND
none  detectable
DO
detectable  obvious
ON
obvious  none
Local
Random
Scalefree
Social
DB
death  birth
RS
removed  susceptible
SE
susceptible  exposed
EI
exposed  infectious
IR
infectious  removed
Discrete Event Simulator
Individual-based Simulation
The discrete event simulation distinguishes tree types of events. The first type implements the standard SEIRS infection dynamics with susceptible, exposed, infectious and recovered states as well as vaccination and a simple birth/death process. The second type models the visibility of the disease according to none, detectable or obvious symptoms. The third type allows to model intervention strategies (like contact tracing, quarantine and case isolation), which influence the contact structure of individuals. Events can trigger further events for __
The inhabitants of the population are represented by their internal state (infection, symptom and contact status) and represent nodes in a contact network. The modular design allows to exchange the contact network independent of the chosen discrete event model. For each individual the contact network allows to identify a limited number of contacts for transmission of the infection or for implementing contact tracing interventions. Currently there exist parameterized
network generators for local, global, random and scalefree contact networks. Moreover, the data struc-ture allows to maintain arbitrary networks consis-ting of several independent layers. We were able to simulate populations of two million individuals on a personal computer.
the same individual and via the contact network for other individuals. All events are processed in a discrete event simulator which is optimized for large numbers of events using a priority queue (indirect heap algorithm) and can process about events per second.