State variable initial values (t = 0) Units
𝑛
s
u
s
=
𝑛
c
i
t
y
−
𝑛
i
n
f
1
−
𝑛
r
e
c
Susceptibles Persons
𝑛
i
n
f
1
=
1
Infecteds Persons
𝑛
r
e
c
=
0
usually, but see Figure 3(c) Recovered (immune) Persons All other
𝑛
x
x
x
,
𝑛
x
x
x
x
=
0
(Figure 1 ) Persons, viruses Parameters + value Description Units
𝑓
a
s
y
=
0
.
9
Asymptomatic fraction (3 )
𝑓
h
o
s
=
0
.
0
5
Fraction of sick hospitalized (4 )
𝑘
a
s
y
=
2
Transfer rate (7 ) Day−1
𝑘
d
e
l
=
1
0
/
1
0
9
5
(see
𝜏
i
m
m
below)Transfer rate (11 ) Day−1
𝑘
h
o
s
=
2
Transfer rate (8 ) Day−1
𝑘
i
n
f
=
2
Transfer rate (3 ) Day−1
𝑘
r
e
c
=
0
(
o
r
1
)
Rate constant (10 ) Day−1
𝑘
s
i
c
=
2
Transfer rate (4 ) Day−1
𝑘
v
i
r
=
2
0
0
Virus production parameter (13 ) Virus units person−1 day−1
𝑘
v
i
r
,
d
n
m
=
5
Virus natural mortality (15 ) Day−1
𝑛
c
i
t
y
=
1
0
6
Population of city (see 1st line of table, paragraph before (1 ), and paragraph after (2 )) Persons
𝑅
0
= 4.78 by (20 )Basic reproductive ratio β Infection transmission rate (2 ) Persons (virus units)−1 day−1
𝜇
=
1
/
(
6
0
×
3
6
5
)
=
4
.
5
6
6
×
1
0
−
5
Natural birth/death rate (2 ) Day−1
𝜇
h
o
s
=
0
.
0
0
1
Flu-induced death rate (hospital) (8 ) Day−1
𝜇
s
i
c
=
0
.
0
0
1
Flu-induced death rate (home) (4 ) Day−1
𝜏
g
e
n
=
2
.
5
1
((B.7 ); see 2nd paragraph after (22 ))Generation time Day−1
𝜏
i
m
m
=
3
×
3
6
5
=
1
0
9
5
Loss of immunity delay (11 ) Day Environmental parameters Description Units
𝑞
T
=
2
Temperature exponent (18 )
𝑠
e
n
v
=
0
(1 )Environment switch (18 )
𝑇
a
i
r
0
=
1
3
Temperature threshold (18 )
°C
𝑘
T
a
i
r
=
0
.
1
Scaling factor (18 ) (°C)−2
d
−
1
Variables Description Units
𝑘
h
o
s
Hospital admission rate (5 ) Persons day−1
𝑘
v
i
r
,
e
n
v
Environmentally induced death rate ((18 ), (15 )) Day−1
𝑅
0
Basic reproductive ratio (20 )
𝑠
i
n
f
Infectious strength (virus production rate) (13 ) Virus person−1 day−1
