Database Reference
In-Depth Information
SICK:
1 -
2 -
1:
300000
1:
150000
2
2
2
2
1
1
1
1
1:
0
0.00
75.00
150.00
225.00
300.00
Weeks
Fig. 2.5
The model results are shown in Figure 2.5. The loss of immunity dampens the
effect of the disease—outbreaks after the first occurrence are less severe and in the
long run, the number of sick people is constant. That number is typically larger than
would be the case of permanent immunity.
LOSS OF IMMUNITY
CONTAGIOUS(t)
=
CONTAGIOUS(t
−
dt)
+
(GET SICK
−
STAY IN BED) * dt
INIT CONTAGIOUS
=
1
{
Individuals
}
INFLOWS:
GET SICK
=
CONTACT RATE * (CONTAGIOUS
+
SICK) * NON IMMUNE
{
Individuals per Time Period
}
OUTFLOWS:
STAY IN BED
=
CONTAGIOUS
{
Individuals per Time Period
}
IMMUNE(t)
=
IMMUNE(t
−
dt)
+
(RECOVER
−
LOSE IMMUNITY) * dt
INIT IMMUNE
=
0
{
Individuals
}
INFLOWS:
RECOVER
=
.9*SICK
{
Individuals per Time Period
}
OUTFLOWS:
LOSE IMMUNITY
=
.1*IMMUNE
NON IMMUNE(t)
=
NON IMMUNE(t
−
dt)
+
(BIRTHS
+
LOSE IMMUNITY
−
GET SICK) * dt
INIT NON IMMUNE
=
1000000
{
Individuals
}
INFLOWS:
BIRTHS
=
5000
{
Individuals per Time Period
}
LOSE IMMUNITY
=
.1*IMMUNE
