SEIR Epidemic Model

Seasonal forcing, births/deaths, vaccination — endemic equilibria and epidemic waves

R₀: 3.0

Vaccination: 0.0

Seasonality: 0.1

1/γ days: 5

Day: 0 | S: 100% | I: 0% | Herd immunity: –

S=Susceptible (blue) · E=Exposed (yellow) · I=Infectious (red) · R=Recovered (green). Herd immunity threshold = 1−1/R₀. Seasonality causes annual epidemic waves.