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A mathematical model for infectious disease epidemics with behaviour change and treatment is formulated and analysed. It is indicated that behaviour modification by the population has a significant impact on the dynamics of the disease. Moreover, an optimal control theory is applied to propose the best possible combination of efforts in controlling a disease. It is shown that it may not be necessary to continuously apply treatment at a full rate to eradicate the disease, if the effort is supported by effective behaviour modification strategies.

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5In this article, a mathematical model for the transmission of COVID-19 disease is formulated 6 and analysed. It is shown that the model exhibits a backward bifurcation at R 0 = 1 when recovered 7 individuals do not develop a permanent immunity for the disease. In the absence of reinfection, it is 8 proved that the model is without backward bifurcation and the disease free equilibrium is globally 9 asymptotically stable for R 0 < 1. By using available data, the model is validated and parameter 10 values are estimated. The sensitivity of the value of R 0 to changes in any of the parameter values 11 involved in its formula is analysed. Moreover, various mitigation strategies are investigated using 12 the proposed model and it is observed that the asymptomatic infectious group of individuals may 13 play the major role in the re-emergence of the disease in the future. Therefore, it is recommended 14 that in the absence of vaccination, countries need to develop capacities to detect and isolate at least 15 30% of the asymptomatic infectious group of individuals while treating in isolation at least 50% of 16 symptomatic patients to control the disease.