Getting started

In this simulation, you can see how a virus spreads across a population over time, and its associated effects on the economy and income inequality. You can compare the outcomes under two different scenarios: no virus mitigation measures, and social distancing.

We use a simple network to represent the population. Each individual is a node and is connected to a fixed number of other individuals, from whom he/she can catch or transmit the virus. At any point in time, an individual can be: 1. uninfected, 2. asymptomatic, 3. quarantined (self-isolating or too ill to interact with others), or 4. recovered. We assume that only asymptomatic individuals spread the virus (in the period after they are exposed to the virus), and recovered individuals are immune from the virus for the duration of the simulation.

You can use the sliders on the top to change the factors that affect the epidemic curve:

• Number of nodes - population size. (Tip: try smaller population sizes e.g. 8 or 10 people to familiarise yourself with the variables before moving on to larger population sizes.)
• Probability of infecting - the likelihood that an infected person will infect an uninfected person whom they are connected to in the network.
• Number of edges - number of other people that each individual is connected to. (Note: if a person is quarantined, all the links between that individual and other people are severed until that person recovers.)
• Social distancing - the number of links between an individual and their contacts that are broken (e.g. via stay-at-home orders or working from home). You can choose any number between 0 (no virus mitigation) and the number of edges currently selected.

Using the 'Simulation type' drop-down menu, you can view the simulation in either static format (all time periods, from the first infection until there are zero active cases) or dynamic format (one time period at a time). Note that due to the random elements in the simulation, each time you run it, the economic cost and Gini curves will look somewhat different. Use the 'Reset' button (Static mode only) to rerun the simulation using different random values.

Spread with no mitigation

Spread with social distancing

Key concepts

Value - the gains from trade from the interaction between two nodes (individuals) in the network.

R₀ - the number of people that one infected person is expected to infect, assuming everyone is completely susceptible to the virus (i.e. the probability of infecting multiplied by the number of edges in the network).