AI-generated content

This chapter was automatically generated by an AI agent and has not been reviewed by a human. Read with caution.

Agents

Agents are the fundamental units of an epiworld simulation. Each agent represents an individual in the population and carries information about their health status, connections, viruses, and tools.

Viruses and Tools

Agents carry two key collections:

• Viruses — Disease agents that can infect the individual and be transmitted to contacts.
• Tools — Interventions such as vaccines, masks, or natural immunity that modify transmission and recovery probabilities.

Each agent can hold multiple viruses and tools simultaneously, meaning that multiple diseases and interventions can coexist in a single simulation.

State Changes

At each step of the simulation, an agent can undergo any of the following changes:

Action	Description
Acquire a virus (add_virus())	Become exposed to a virus from a contact.
Lose a virus (rm_virus())	Recover from or clear a virus. Triggers the virus's postrecovery() function, which can grant immunity.
Acquire a tool (add_tool())	Gain a tool such as a vaccine or mask.
Lose a tool (rm_tool())	Lose a tool, e.g., immunity waning or stopping mask use.
Change state (change_state())	Transition to a different compartment, e.g., from "Exposed" to "Infected" or from "Infected" to "ICU."

Queuing Effects

Any action in the model can trigger a change in the queuing system:

• Becoming exposed makes the agent (and its neighbors) active in the queue, ensuring they are evaluated in subsequent steps.
• Losing all viruses can make the agent and its neighbors inactive, allowing the simulation to skip them and run faster.