This model tracks susceptibles, exposed/pre-symptomatic, infected/symptomatic and recovered hosts. The following compartments are included:
The included processes/mechanisms are the following:
The flow diagram for the model implemented in this app is:
Flow diagram for this model.
Note that this model is not an ordinary differential equation model. It is instead its stochastic equivalent. We can specify the model by writing down every possible transition/event/reaction that can occur and their propensities (the propensity multiplied with the time step gives the probability that a given event/transition occurs). For our model these are the following:
Event type | Transitions | Propensity |
---|---|---|
Infection | S => S-1, E => E+1 | S(bEE+bII) |
Progression to Symptoms | E => E-1, I => I+1 | gEE |
Recovery | I => I-1, R => R+1 | gII |
Waning of Immunity | R => R-1, S => S+1 | wR |
Births | S => S+1 | eS |
Death of susceptible | S => S-1 | nS |
Death of exposed | E => E-1 | nE |
Death of symptomatic | I => I-1 | nI |
Death of recovered | R => R-1 | nR |