Difference between revisions of "SIR model: swine flu"
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* In [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2715422 Modeling influenza epidemics and pandemics: insights into the future of swine flu (H1N1)] the authors estimate the reproduction rate <math>R_0</math> of the virus to be about <math>2</math>. For the SIR model this means: the reproduction rate <math>R_0</math> for influenza is equal to the infection rate of the strain (<math>\beta</math>) multiplied by the duration of the infectious period (<math>1/\gamma</math>), i.e. | * In [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2715422 Modeling influenza epidemics and pandemics: insights into the future of swine flu (H1N1)] the authors estimate the reproduction rate <math>R_0</math> of the virus to be about <math>2</math>. For the SIR model this means: the reproduction rate <math>R_0</math> for influenza is equal to the infection rate of the strain (<math>\beta</math>) multiplied by the duration of the infectious period (<math>1/\gamma</math>), i.e. | ||
:<math>\beta = R_0\cdot \gamma</math>. Therefore, we set the :<math>\beta = 2\cdot 1/7 = 0.2857</math> | :<math>\beta = R_0\cdot \gamma</math>. Therefore, we set the :<math>\beta = 2\cdot 1/7 = 0.2857</math> | ||
| − | * We run the simulation for a population of 1 million people, where 1 person is infected initially, i.e. <math>s= 1E-6</math>. | + | * We run the simulation for a population of 1 million people, where 1 person is infected initially, i.e. <math>s=1E{-6}</math>. |
Thus S(0) = 1, I(0) = 1.E-6, R(0) = 0 | Thus S(0) = 1, I(0) = 1.E-6, R(0) = 0 | ||
<html> | <html> | ||
| − | <form><input type="button" value="clear and run a simulation of | + | <form><input type="button" value="clear and run a simulation of 200 days" onClick="clearturtle();run()"> |
<input type="button" value="stop" onClick="stop()"> | <input type="button" value="stop" onClick="stop()"> | ||
<input type="button" value="continue" onClick="goOn()"></form> | <input type="button" value="continue" onClick="goOn()"></form> | ||
</html> | </html> | ||
<jsxgraph width="700" height="500"> | <jsxgraph width="700" height="500"> | ||
| − | var brd = JXG.JSXGraph.initBoard('jxgbox', {originX: 20, originY: 300, unitX: | + | var brd = JXG.JSXGraph.initBoard('jxgbox', {originX: 20, originY: 300, unitX: 3, unitY: 250, axis:true}); |
var S = brd.createElement('turtle',[],{strokeColor:'blue',strokeWidth:3}); | var S = brd.createElement('turtle',[],{strokeColor:'blue',strokeWidth:3}); | ||
| Line 17: | Line 17: | ||
var R = brd.createElement('turtle',[],{strokeColor:'green',strokeWidth:3}); | var R = brd.createElement('turtle',[],{strokeColor:'green',strokeWidth:3}); | ||
| − | + | var s = brd.createElement('slider', [[0,-0.3], [60,-0.3],[0,1E-6,1]], {name:'s'}); | |
| − | |||
| − | |||
| − | var s = brd.createElement('slider', [[0,-0.3], [ | ||
brd.createElement('text', [40,-0.3, "initially infected population rate"]); | brd.createElement('text', [40,-0.3, "initially infected population rate"]); | ||
| − | var beta = brd.createElement('slider', [[0,-0.4], [ | + | var beta = brd.createElement('slider', [[0,-0.4], [60,-0.4],[0,0.2857,1]], {name:'β'}); |
brd.createElement('text', [40,-0.4, "β: infection rate"]); | brd.createElement('text', [40,-0.4, "β: infection rate"]); | ||
| − | var gamma = brd.createElement('slider', [[0,-0.5], [ | + | var gamma = brd.createElement('slider', [[0,-0.5], [60,-0.5],[0,0.1428,1]], {name:'γ'}); |
brd.createElement('text', [40,-0.5, "γ: recovery rate = 1/(days of infection)"]); | brd.createElement('text', [40,-0.5, "γ: recovery rate = 1/(days of infection)"]); | ||
var t = 0; // global | var t = 0; // global | ||
| − | brd.createElement('text', [ | + | brd.createElement('text', [90,-0.2, |
function() {return "Day "+t+": infected="+brd.round(1000000*I.Y(),1)+" recovered="+brd.round(1000000*R.Y(),1);}]); | function() {return "Day "+t+": infected="+brd.round(1000000*I.Y(),1)+" recovered="+brd.round(1000000*R.Y(),1);}]); | ||
| Line 69: | Line 66: | ||
t += delta; | t += delta; | ||
| − | if (t< | + | if (t<200.0) { |
active = setTimeout(loop,10); | active = setTimeout(loop,10); | ||
} | } | ||
Revision as of 12:31, 10 August 2009
The SIR model tries to model influenza epidemics. Here, we try to medel the spreading of the swine flu.
- According to the CDC Centers of Disease Control and Prevention: "Adults shed influenza virus from the day before symptoms begin through 5-10 days after illness onset. However, the amount of virus shed, and presumably infectivity, decreases rapidly by 3-5 days after onset in an experimental human infection model." So, here we set [math]\gamma=1/7=0.1428[/math] as the recovery rate. This means, on average an infected person sheds the virus for 7 days.
- In Modeling influenza epidemics and pandemics: insights into the future of swine flu (H1N1) the authors estimate the reproduction rate [math]R_0[/math] of the virus to be about [math]2[/math]. For the SIR model this means: the reproduction rate [math]R_0[/math] for influenza is equal to the infection rate of the strain ([math]\beta[/math]) multiplied by the duration of the infectious period ([math]1/\gamma[/math]), i.e.
- [math]\beta = R_0\cdot \gamma[/math]. Therefore, we set the :[math]\beta = 2\cdot 1/7 = 0.2857[/math]
- We run the simulation for a population of 1 million people, where 1 person is infected initially, i.e. [math]s=1E{-6}[/math].
Thus S(0) = 1, I(0) = 1.E-6, R(0) = 0
