“…Specifically, we re-establish the GAS of DFSS in a simple and direct manner and furthermore, resolve the GAS of ESS by rigorous mathematical theory. Here, the method adopted is Lyapunov's direct functional, which had been used widely to derive the global stability in various of epidemic models, such as ordinary differential models, 2,3 delay epidemic models, 4,5 age-structured models, [6][7][8][9][10] reaction-diffusion models, 11,12 and nonlocal diffusion models, 13,14 and so on. The key skill for constructing Lyapunov functionals is to select some novel appropriate kernel functions.…”