“…Stone, Shulgin, and Agur (2000) presented a theoretical examination of the PVS in the SIR epidemic model and d 'Onofrio (2002a'Onofrio ( , 2002b analysed the use of pulse vaccination policy to eradicate infectious disease for SIR and SEIR epidemic models. Different types of vaccination policies and strategies combining pulse vaccination policy, treatment, pre-outbreak vaccination or isolation have already been introduced by several researchers (Babiuk, Babiuk, & Baca-Estrada, 2002;d'Onofrio, 2005;Gao, Chen, Nieto, & Torres, 2006;Gao, Chen, & Teng, 2007;Gjorrgjieva et al, 2005;Tang, Xiao, & Clancy, 2005;Wei & Chen, 2008;Zhang & Teng, 2008).…”