Designed for Google Chrome
Transmission rate (1%)
Number of common areas (5)
Common area popularity (30%)
Cheating (10%)
Healthy Asymptomatic Symptomatic Sent home sick Recovered
The chart is greyed when everyone is sent home
Minor ticks: days      Major ticks: weeks

The 1000 agents in this simulation travel between random locations, interacting with each other on contact. Black circles represent high-traffic common areas, such as grocery stores and restaurants. The common area popularity slider adjusts the probability that any agent will choose a common area for its next goal.

Each interaction between two agents has a probability of causing a transmission event, during which the agents share their viral load additively. If an agent's viral load is high enough they get a normally-distributed random incubation period with a mean of 5 days and a range of 2.4 to 14 days (1).

When they're done incubating they're marked symptomatic, and the send home if showing symptoms switch stops their random movement. Agents won't isolate until they have symptoms.

Once agents finish incubating they're given a random recovery time with a mean of 14 days and a range of 7 to 28 days (2). Their viral load decreases during recovery, so they become less contagious until they're recovered. Recovered agents can't be reinfected.

Every agent has a home, which is where they go when you check the send home switch. The homes are on the outskirts of the field (the residential area) so they don't interact with the active population. Every agent has a 10% chance to go home each time they pick a new goal, and they can interact with quarantined agents when they pass by.

The cheating rate determines the probability that any quarantined agent will begin one round trip from their home each tick.

The minor ticks on the graph are days, major ticks are weeks, and vertical lines delineate months. The simulation runs at 100Hz and computes 24 hours each second; one tick is therefore just over 14 minutes. 

The speed of the agents is such that they reach 4 goal locations each day; either a random location, a common location, or their home.

(1) The Incubation Period of Coronavirus Disease 2019 (COVID-19) From Publicly Reported Confirmed Cases: Estimation and Application

(2) Patient Medical Data for COVID-19