“…Remark 2.1. According to [19], note that the set Γ = {(S(t), E(t), I(t), P(t), H(t), A(t), R(t)) : S(t) > 0, E(t) > 0, I(t) > 0, P(t) > 0, H(t) > 0, A(t) > 0, R(t) > 0, N(t) ≤ Λ/µ is a positively invariant set of the system (1) for every t > 0, i.e. if the system starts from Γ , it never leaves Γ .…”