Table 1.

Compartments of the epidemiological model, indicating the stage of infection for different proportions of the population.

Compartment	Definition
S	Susceptible to infection.
En	Non-infectious exposed, representing infected individuals in the non-infectious phase of the incubation period.
Ei	Infectious exposed, representing infected individuals in the “presymptomatic” phase of the incubation period where onward transmission can occur.
Ie	Early actively infectious, individuals are transmitting disease but not (yet) detected.
Il	Late actively infectious, symptomatic individuals are detected (for those whom detection does occur) and isolation and hospitalisation occurs.
R	Recovered and removed (i.e., dead).