Difference between revisions of "SEIR"
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The parameter β basically represents the probability of a susceptible person meeting an infected person. (Social distancing would decrease β for example.) The first derivative of S with respect to time (denoted by a dot on top of the variable S) is thus -βSI. | The parameter β basically represents the probability of a susceptible person meeting an infected person. (Social distancing would decrease β for example.) The first derivative of S with respect to time (denoted by a dot on top of the variable S) is thus -βSI. | ||
| − | A formerly susceptible person which has been exposed to an infected person | + | A formerly susceptible person which has been exposed to an infected person is thus removed from the set of susceptible persons and becomes an exposed person E. |
[[File:SEIR_program.pdf|512px]] | [[File:SEIR_program.pdf|512px]] | ||
Revision as of 18:11, 17 August 2021
In this example a simple SEIR-model of an infectious disease is setup. This is a classical model with four time varying variables representing the set of susceptible, exposed, infected, and recovered persons.
The model is described by four coupled differential equations, one for each of the four variables. Initially, all persons are susceptible in a simulation as they have not been exposed to the disease yet. The number of susceptible persons is computed by the topmost integrator in the program shown below. This integrator has an initial condition of -1 thus yielding S=+1 initially.
The parameter β basically represents the probability of a susceptible person meeting an infected person. (Social distancing would decrease β for example.) The first derivative of S with respect to time (denoted by a dot on top of the variable S) is thus -βSI.
A formerly susceptible person which has been exposed to an infected person is thus removed from the set of susceptible persons and becomes an exposed person E.
