← Worked Biological Models

SEIR project

The SEIR model introduces an exposed class for infected individuals who are not yet infectious:

\[\frac{dS}{dt}=-\beta\frac{SI}{N},\quad \frac{dE}{dt}=\beta\frac{SI}{N}-\sigma E,\quad \frac{dI}{dt}=\sigma E-\gamma I,\quad \frac{dR}{dt}=\gamma I.\]

The mean exposed duration is \(1/\sigma\), while the mean infectious duration is \(1/\gamma\).

Investigation

Compare an SEIR trajectory with an SIR model using similar transmission and recovery assumptions. Vary \(\sigma\) to examine how the latent period changes the timing of infectious prevalence.

Capacity extension

Map a defined fraction or delayed flow of severe cases into a hospital compartment and compare predicted occupancy with a capacity threshold.

Project outcome. Show how adding a biologically meaningful latent stage changes epidemic timing and downstream demand.

Prerequisite and implementation

Review the SEIR theory lesson for model construction, then use SEIR with Euler’s method for detailed programming. This page serves as the combined worked example.