In this study, we propose a new mathematical model and analyze it to understand the transmission dynamics of the COVID-19 pandemic in Bangkok, Thailand. It is divided into seven compartmental classes, namely, susceptible
S
,
exposed
E
,
symptomatically infected
I
s
,
asymptomatically infected
I
a
,
quarantined
Q
,
recovered
R
,
and death
D
, respectively. The next-generation matrix approach was used to compute the basic reproduction number denoted as
R
cvd
19
of the proposed model. The results show that the disease-free equilibrium is globally asymptotically stable if
R
cvd
19
<
1
. On the other hand, the global asymptotic stability of the endemic equilibrium occurs if
R
cvd
19
>
1
. The mathematical analysis of the model is supported using numerical simulations. Moreover, the model’s analysis and numerical results prove that the consistent use of face masks would go on a long way in reducing the COVID-19 pandemic.