Variable

Meaning

$S\left(t\right)$

The number of susceptible individuals at time t in the population.

$E\left(t\right)$

The number of exposed individuals at time t in the population.

$I\left(t\right)$

The number of symptomatically infective individuals at time t in the population.

$A\left(t\right)$

The number of asymptomatically infective individuals at time t in the population.

$R\left(t\right)$

The number of recovered individuals at time t in the population.