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Discrete Dynamics in Nature and Society
Volume 2008, Article ID 746951, 12 pages
Research Article

A Delayed Epidemic Model with Pulse Vaccination

1Department of Applied Mathematics, Dalian University of Technology, Dalian 116024, China
2School of Sciences, Jimei University, Xiamen 361021, China

Received 14 November 2007; Revised 7 January 2008; Accepted 18 February 2008

Academic Editor: Leonid Berezansky

Copyright © 2008 Chunjin Wei and Lansun Chen. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


A delayed SEIRS epidemic model with pulse vaccination and nonlinear incidence rate is proposed. We analyze the dynamical behaviors of this model and point out that there exists an infection-free periodic solution which is globally attractive if 𝑅1<1, 𝑅2>1, and the disease is permanent. Our results indicate that a short period of pulse or a large pulse vaccination rate is the sufficient condition for the eradication of the disease. The main feature of this paper is to introduce time delay and impulse into SEIRS model and give pulse vaccination strategies.