Outbreak Simulator
The SEIR model splits a population into Susceptible, Exposed, Infectious and Recovered, and moves people between them day by day. Set how contagious a disease is, then try to keep the hospital load under the line.
The disease illustrative
The response
One year, 1 million people
Hospital beds needed line: beds free · dashed: no response
R0 and the effective R
R0 is how many people one case infects when nobody is immune. As people recover or are vaccinated, each case finds fewer people to infect, so the effective R falls. The outbreak shrinks once it drops below 1.
Why flattening matters
Distancing does not always change how many people get infected in the end, but it spreads them out. A lower, later peak can mean everyone who needs a hospital bed gets one.
What the model leaves out
Real populations are not perfectly mixed: age, households, travel and changing behaviour all matter, and immunity can fade. SEIR is the starting point epidemiologists build on, not a forecast.
Parameters and presets are illustrative, chosen to show the model's behaviour, not to describe any real disease precisely. The model is the standard SEIR compartmental model, solved in small daily steps. Educational only; not medical or public-health advice.