An SIR model is an epidemiological model that computes the theoretical number of people infected with a contagious illness in a closed population over time. The name
of this class of models derives from the fact that they involve coupled equations
relating the number of susceptible people , number of people infected , and number of people who have recovered . One of the simplest SIR models is the Kermack-McKendrick
The Season 1 episode "Vector" (2005) of the television crime drama NUMB3RS
features SIR models.