Flu Model Equations

Stella® Rendition of Flu Model Equations

Variable Descriptions:

infected: total number of people infected with the flu at some point in time

susceptible: total number of people susceptible to the flu at some point in time(i.e., people who have not been vaccinated)

infection_rate: constant rate (0.0-1.00) at which the susceptible fraction of the population is infected during one time step

recovery_rate: constant rate (0.0-1.00) at which the infected population recovers during one time step

get_well: the number of people who get well in a time step

get_sick: the number of people who get sick in a time step

recovered: the total number of people who have recovered from the flu at some point in time

t: time (days)

dt: time step (decimal fraction of one day)

Stella Algorithm (w/ initializations for a sample run)

Initializations:

INIT infected = 1
INIT susceptible = 762
infection_rate = .00218
get_sick = infected*susceptible*infection_rate
recovery rate = .5
get_well = infected*recovery_rate
INIT recovered = 0

Runtime Equations:

infected(t) = infected(t - dt) + (get_sick - get_well) * dt
susceptible(t) = susceptible(t - dt) + (- get_sick) * dt
recovered(t) = recovered(t - dt) + (get_well) * dt
get_sick = infected*susceptible*infection_rate
get_well = infected*recovery_rate

Stella® Rendition of Flu Model Equations

Variable Descriptions:

Stella Algorithm (w/ initializations for a sample run)

Initializations:

Runtime Equations:

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