SEIR-VQ model for the NB.1.8.1 COVID-19 variant: Mathematical analysis and numerical simulations

This the study proposes a novel susceptible, exposed, infectious, recovered, vaccinated, and quarantined (SEIR-VQ)-type compartmental model specifically designed to capture the transmission dynamics of the NB.1.8.1 variant of COVID-19, a recently emerged virus known for its higher transmissibility and reduced vaccine effectiveness. The model divides the population into six distinct compartments: Susceptible, exposed, infectious, quarantined, recovered, and vaccinated. The proposed formulation reflects key contemporary epidemiological factors, such as waning immunity, partial vaccine effectiveness due to viral mutations, and infectivity during quarantine. Additionally, the study conducts both dimensional and non-dimensional analyses of the system, establishes the positivity and boundedness of solutions, and derives the basic reproduction number, $ \mathcal{R}_0 $. It also examines the local and global stability of the disease-free equilibrium with respect to $ \mathcal{R}_0 $. Numerical solutions utilizing the Runge-Kutta (RK4) method and MATLAB's ode45 solver are used to simulate infection dynamics. Finally, a sensitivity analysis evaluates the influence of the key parameters that most significantly impact disease spread. The findings indicate that increasing vaccine efficacy, reducing transmission through non-pharmaceutical interventions, and enhancing the isolation of infectious individuals are effective strategies for controlling the spread of the NB.1.8.1 variant. These results support public health policies by highlighting effective control strategies.