COVID-19 Outbreak and Policies

This model is seeking new collaborators — would you please help?

1 collaborator

CJ Castillo (Author)

WHAT IS IT?

This is a model of COVID-19 outbreak.

HOW IT WORKS

In this model, humans are either healthy or infected (sick). Green humans are healthy. Infected humans are either colored red or yellow. Healthy humans can be infected when they get close to sick humans (both red and yellow). Infected humans can get well by chance.

Red infected humans are those that have been confirmed through testing. Healthy humans avoid those who have tested positive (red humans). The distance healthy humans keep between them and confirmed infected depends on the number of red humans: when there are more confirmed infected humans, healthy humans stay farther from confirmed infected humans.

Yellow infected humans are sick people who have not been tested. Healthy people cannot distinguish between yellow and green humans. Yellow infected humans turn red when there is mass testing.

HOW TO USE IT

Use the slider to select population size. Click Setup to initiate the model. Click Infect to infect a random healthy individual. Click Run to run the model. Switch on Mass-test? to identify which are the sick humans. Switch on Quarantine? to limit the movement of confirmed sick humans. Switch on Lockdown? to limit the movement of all humans.

Infect humans at will by pressing Infect.

THINGS TO NOTICE

The number of sick humans is plotted against time. Observe tipping points or reversal of trends.

THINGS TO TRY

Experiment with combination of policies (mass-testing, quarantine, and lockdown) to control outbreak.

EXTENDING THE MODEL

To extend the model, variables such as costs of policies (mass-testing, quarantine, lockdown) can be incorporated.

Mortality can also be incorporated.

CREDITS AND REFERENCES

Author: CJ Castillo Version 3

Comments and Questions

Pradeesh K V

Good Model

The model is simple yet provides a nice insight into the dynamics of the disease. The code is simple and straightforward with sufficient description provided in the info tab. My minor comment is that you have modelled healthy people to avoid tested infected people. (1) In reality, how can a person know whether the other person is infected or not? (2) If the person is tested positive, he/she will be kept in isolation. Therefore, it is unlikely that a healthy person will meet a tested infected person. In my understanding so far, infection is happening during the period when the person begins to show symptoms (even minor) and before he gets tested and is put in isolation. Best,

Posted over 5 years ago

Click to Run Model

breed[healthys healthy]
;;healthys-own [color shape]
breed[sicks sick]
sicks-own [recovery]
turtles-own [susceptibility job PPE speed] ;;Probability of contracting the disease

to setup
  clear-all
  reset-ticks
  create-healthys Population [
    setxy random-xcor random-ycor
    set susceptibility random-float 1
    set shape "person"
    set color green
    set breed healthys
    set job "Citizen"
    set heading random 360
    set speed 0.1
  ]
end 

to infect ;; creates an infection
 ;;create-sicks 1 [
 ;;   setxy random-xcor random-ycor
 ;;   set heading random 360
 ;;   set shape "person"
 ;;   set breed sicks
 ;;   set color yellow
 ;;   set job "citizen"
 ;;   set recovery random-float .5
 ;; ]
 ask one-of healthys [
    set breed sicks
    set color yellow
    set shape "person"
    set recovery random-float .5
    set speed 0.1
  ]
end 

to go
  ask turtles [
    let current-turtle self
    forward speed display
    if distance current-turtle < 1 + (count sicks) [
      set heading heading + (random-float 5 - random-float 5)]
  ]
  stay-away
  epidemic
  get-well
  quarantine
  mass-test
  lockdown
  tick
end 

to epidemic
  ask sicks [
    let current-sick self
    ask healthys with [distance current-sick < 1] [
      set breed sicks
      set color yellow
      set shape "person"
      set recovery random-float 1
      set speed 0.1
    ]
  ]
end 

to get-well
  ask sicks [
    set recovery recovery + (random-float .5) - (random-float .5)
    if recovery > .8 [
      set breed healthys
      set shape "person"
      set color green
      set speed 0.1
    ]
  ]
end 

to plot-agents
  plot count sicks
  plot count healthys
end 

to stay-away  ;;Ask healthy people to stay away from sicks who have been identified through mass-testing
  ask sicks with [color = red] [
    let current-sick self
    ask healthys with [distance current-sick < (count sicks with [color = red])] [
      set heading towards current-sick  ;; to move away, first the healthy faces the sick then makes 180 degree turn.
      set heading heading + 180
    ]
  ]
end 

to quarantine ;; Ask confirmed sick people to limit their movement.
ifelse Quarantine-sick?
  [ask sicks with [color = red] [set speed 0.00001]]
  [ask sicks with [color = yellow] [set speed 0.1]]
end 

to mass-test ;; Ask all sicks to disclose their sickness
  ifelse Mass-test?
  [ask sicks [set color red]]
  [ask sicks [set color yellow]]
end 

to lockdown
  ifelse Lockdown?
  [ask turtles [set speed 0]]
  [ask healthys [set speed 0.1]
    ask sicks with [color = red] [ifelse Quarantine-sick?
      [set speed 0.00001]
      [set speed 0.1]]
    ask sicks with [color = yellow] [set speed 0.1]
  ]
end

There is only one version of this model, created over 5 years ago by CJ Castillo.

Attached files

File	Type	Description	Last updated
COVID-19 Outbreak and Policies.png	preview	Preview for 'COVID-19 Outbreak and Policies'	over 5 years ago, by CJ Castillo	Download

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