Epidemiology
SIR Model
The compartmental model of infectious-disease spread.
dS/dt=−βSI, dI/dt=βSI−γI, dR/dt=γI
What it means
The SIR model partitions a population into susceptible, infected, and recovered compartments, with transmission rate β and recovery rate γ governing outbreak dynamics and herd immunity.
Variables
| S | susceptible fraction |
| I | infected fraction |
| R | recovered fraction |
| β | transmission rate |
| γ | recovery rate |
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