“…See, for instance, Reference [15]. Assume that the basic reproduction number [5,6], is less than unity so that the disease-free equilibrium point x e = (S e , 0 , 0 , N(0) − S e ) T 0 is globally asymptotically stable, [3,5,6]. Since x(t) → x e as t → ∞ , it turns out that, for t * = +∞ , no other targeted state x * ( x e ) can be prefixed as objective for any given initial state x(0) even for the current linearized version.…”