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Pulse Vaccination Strategy in an Epidemic Model with Time Delays and Nonlinear Incidence

In this paper, we formulate an SEIRS epidemic model with two time delays and pulse vaccination. By estabishing stroboscopic map, we obtain the exact infection free periodic solution of the impulsive epidemic system. According to the comparison arguments, we obtain the sufficient conditions of global attractivity of the infection free periodic solution. Moreover, our results show that a large vaccination or a short pulse of vaccination or a long latent period or a long immune period will lead to the extinction of the disease. The permance of the model is also discussed.