SVEIRS: A New Epidemic Disease Model with Time Delays and Impulsive Effects

Figure 1

The results of numerical simulation on the threshold values ℛ₂=2.6155>1, where 𝑝=1.5, 𝑞=1.25.

(a) Time series of 𝑆, 𝑉, and 𝐼. The disease will be permanent

(b) Phase portrait of 𝑆(𝑡), 𝑉(𝑡) of the system  (4)

(c) Phase portrait of 𝑆(𝑡), 𝐼(𝑡) of the system  (4)

(d) Phase portrait of 𝑆(𝑡), 𝑉(𝑡), and 𝐼(𝑡) of the system  (4)