. 2021 Jul 23;105(3):2757–2773. doi: 10.1007/s11071-021-06705-8

Table 1.

Nomenclature

Symbol	Meaning
S	Susceptible
I_j	Infected of the jth virus strain
R	Removed
H	Healed
E	Extinct
OI	Overall infections
OM	Overall mortality
i_j	Undetected asymptomatic patients
d_j	Diagnosed (detected asymptomatic patients)
a_j	Ailing (undetected symptomatic patients)
r_j	Recognized (detected symptomatic patients)
t_j	Threatened (infected with life-threatening symptoms, detected patients)
$α_{j}, β_{j}, γ_{j}, δ_{j}$	Infection rate after contacting with t_j, d_j, a_j,r_j respectively
$ε_{j}, θ_{j}$	Diagnosis rates of patients with state i_j, a_j respectively
$ζ_{j}, η_{j}$	Symptomatic rates of patients with state i_j, d_j respectively
$μ_{j}, v_{j}$	Occurrence rate of life-threatening symptoms in a_j, r_j respectively
$τ_{j}$	Mortality rate of threatened patients
$λ_{j}, κ_{j}, ξ_{j}, ρ_{j}, σ_{j}$	Cure rate of patients with state t_j, d_j, a_j, r_j, t_j, respectively
$ω$	Risk reduction rate of reinfection for individuals who have been healed
C_infection	Score used to value the difference of infections between two strains
C_mortality	Score used to value the difference of mortality between two strains