21.8 Epidemic with Vaccine Model Equations
CONTAGIOUS(t) ¼ CONTAGIOUS(t À dt) + (CONTRACTING À CONTAGIOUS_
DYING À BED_DING) * dt
INIT CONTAGIOUS ¼ 1 {People}
INFLOWS:
CONTRACTING ¼ IF IMMUNE > 0 THEN CC * NON_IMMUMNE * CONTA
GIOUS ELSE 0
OUTFLOWS:
CONTAGIOUS_DYING ¼ CONTAGIOUS * NAT_DEATH_RATE/52 {People
per Week}
BED_DING ¼ CONTAGIOUS-CONTAGIOUS_DYING {People per Week}
IMMUNE(t) ¼ IMMUNE(t À dt) + (RECOVERING + VACCIN_ATING À
IMMUNE__DYING - IMMUNE_LOSS) * dt
INIT IMMUNE ¼ 0 {People}
INFLOWS:
RECOVERING ¼ 0.9 * SICK {People per Week}
VACCIN_ATING ¼ VAC_FRACTION * NON_IMMUMNE - 0.15 * IMMUNE
OUTFLOWS:
IMMUNE__DYING ¼ IMMUNE * NAT_DEATH_RATE/52 {People per Week}
IMMUNE_LOSS ¼ .002 * IMMUNE {People per Week}
NON_IMMUMNE(t) ¼ NON_IMMUMNE(t À dt) + (BIRTHING + IMMUNE_LOSS
À CONTRACTING À NONIMMUNE_DYING À VACCIN_ATING) * dt
INIT NON_IMMUMNE ¼ 1000000 {People}
INFLOWS:
BIRTHING ¼ POPULATION * BIRTH_RATE/52 {People per Week}
IMMUNE_LOSS ¼ .002 * IMMUNE {People per Week}
OUTFLOWS:
CONTRACTING ¼ IF IMMUNE > 0 THEN CC * NON_IMMUMNE * CONT
AGIOUS ELSE 0
NONIMMUNE_DYING ¼ NAT_DEATH_RATE/52 * NON_IMMUMNE {People
per Week}
VACCIN_ATING ¼ VAC_FRACTION * NON_IMMUMNE À 0.15 * IMMUNE
SICK(t) ¼ SICK(t - dt) + (BED_DING À RECOVERING À SICK_DYING) * dt
INIT SICK ¼ 0 {People}
INFLOWS:
BED_DING ¼ CONTAGIOUS-CONTAGIOUS_DYING {People per Week}
OUTFLOWS:
RECOVERING ¼ 0.9 * SICK {People per Week}
SICK_DYING ¼ (.1 * SICK)+(NAT_DEATH_RATE/52 * SICK) {People per Week}
BIRTH_RATE ¼ GRAPH(POPULATION)
(0.00, 0.199), (166667, 0.189), (333333, 0.181), (500000, 0.171), (666667, 0.159),
(833333, 0.146), (1e+06, 0.138), (1.2e+06, 0.133), (1.3e+06, 0.129), (1.5e+06,
0.125), (1.7e+06, 0.123), (1.8e+06, 0.122), (2e+06, 0.12)
21.8 Epidemic with Vaccine Model Equations
179