Table 1.

Description of related parameters in COVID-19 model (2).

Variables and parameters	Description
Variables
$S\left(t\right)$	Health human at time $t$
$E_1\left(t\right)$	Low-risk close contacts at time $t$
$E_2\left(t\right)$	High-risk close contacts at time $t$
$I_1\left(t\right)$	Asymptomatic possible/unconfirmed cases with imaging features of pneumonia
$I_2\left(t\right)$	Mild symptomatic possible/unconfirmed cases with imaging features of pneumonia
$I_3\left(t\right)$	Severe symptomatic possible/unconfirmed cases with imaging features of pneumonia
$T_1\left(t\right)$	Asymptomatic and mild symptomatic patients treated
$T_2\left(t\right)$	Severe symptomatic patients treated
$R\left(t\right)$	Recovered cases
Parameters
$\Lambda$	Recruitment rate
$\mu$	Natural death rate
$\theta$	Proportion of $S$ who become Low-risk exposed people $E_1$
$\beta$	The probability of a susceptible person contracting the disease without any protective measures
${\alpha }_1$	Proportion of valid contact between asymptomatic infected persons $I_1$ and susceptible persons $S$
${\alpha }_2$	Proportion of valid contact between mild symptomatic infected persons $I_2$ and susceptible persons $S$
${\alpha }_3$	Proportion of valid contact between severe symptomatic infected persons $I_3$ and susceptible persons $S$
$v_1$	Rate of moving from $E_1$ to asymptomatic infected $I_1$
$v_2$	Rate of moving from $E_1$ to mild symptomatic $I_2$
$v_3$	Rate of moving from $E_1$ to severe symptomatic $I_3$
$v_4$	Rate of moving from $E_2$ to asymptomatic infected $I_1$
$v_5$	Rate of moving from $E_2$ to mild symptomatic $I_2$
$v_6$	Rate of moving from $E_2$ to severe symptomatic $I_3$
$w_1$	Proportion of $I_1$ assigned to mild treated compartment $T_1$ after diagnosis
$w_2$	Proportion of $I_1$ assigned to severe treated compartment in hospital $T_2$ after diagnosis
$w_3$	Proportion of $I_2$ assigned to mild treated compartment $T_1$ after diagnosis
$w_4$	Proportion of $I_2$ assigned to severe treated compartment in hospital $T_2$ after diagnosis
$w_5$	Proportion of $I_3$ assigned to mild treated compartment $T_1$ after diagnosis
$w_6$	Proportion of $I_3$ assigned to severe treated compartment in hospital $T_2$ after diagnosis
${\eta }_1$	Rate of transfer from mild treated compartment $T_1$ to severe treated compartment $T_2$
${\eta }_2$	Rate of transfer from severe treated compartment $T_2$
${\xi }_1$	Recovery rate of mild treated compartment $T_1$
${\xi }_2$	Recovery rate of severe treated compartment $T_2$
$d$	The proportion of deaths due to infection with COVID-19