@webwriter/epidemic-sim

v1.0.0

Published

8 days ago

Interactive agent-based epidemic simulation (SIR/SIRS/SEIR/SIRD/SEIRD) for WebWriter explorables, with charts, quarantine, hotspots, and communities.

Epidemic Sim (`@webwriter/[email protected]`)

License: MIT | Version: 1.0.0

Interactive agent-based epidemic simulation (SIR/SIRS/SEIR/SIRD/SEIRD) for WebWriter explorables, with charts, quarantine, hotspots, and communities.

What the widget does

The widget simulates how an infection spreads through a population. Learners can watch it unfold, change parameters and compare scenarios.

People as dots. Every person is a dot that moves around a map. When an infected dot comes within the infection radius of a susceptible one, it may pass on the infection (infection probability). Dots are colored by their current state.
Epidemic models. The model decides which states exist:
| Model | States | Typical question | | :---: | :----: | :--------------- | | SIR | Susceptible → Infected → Recovered | Basic course of an epidemic | | SIRS | … → Recovered → Susceptible again | Immunity that wears off | | SEIR | Susceptible → Exposed → Infected → Recovered | Incubation period | | SIRD | … Infected → Recovered or Dead | Mortality | | SEIRD | Incubation period and mortality combined | |
Chart. A line chart shows how many people are in each state on every simulated day. It updates live while the simulation runs.
Interventions that learners can switch on to see their effect:
- Quarantine: infected people are moved to a separate area with a given probability and stay there for a given time.
- Hotspots: places where people gather (e.g. a school or a supermarket). They are placed by dragging or tapping on the map, moved by dragging, resized at their corners and removed by dragging them off the map.
- Communities: the population is split into groups that only rarely mix.
Snapshots. A snapshot stores the course of the curves at one moment. All snapshots can be compared in a gallery and downloaded as an image (PNG) or a table (CSV).
Insights. Key figures such as the estimated R0, the herd immunity threshold, the peak of infections and the current share of each group are shown in the sidebar.
Fullscreen. The whole widget can be enlarged to fill the screen. Chart and map are then shown side by side with the key figures below.

Authors and learners

In WebWriter, authors configure the widget in its options panel: the model, all parameters and which controls learners may see. Every parameter has a matching allow-… attribute; only controls that are allowed appear in the learners' sidebar. Options for switched off features stay hidden until the feature is turned on.

Time

The simulation runs in steps of 24 frames per day. Durations (incubation, recovery, quarantine, …) are stored as a number of frames in the attributes and shown in days in the interface (e.g. 120 frames = 5 days).

Saved state

Settings are stored as attributes. Placed hotspots and snapshots are stored as JSON in the widget-state attribute. Snapshots only contain the data of the curves; the chart is redrawn from that data, so documents stay small.

Snippets

Snippets are examples and templates using the package's widgets.

The snippet is a ready-made task on COVID-19 (SEIRD model). Its parameters are based on published values of the Robert Koch Institute; the sources are listed in the snippet file.