Backward bifurcation in drug-resistant SIR models
by
Ruijun Zhao
Department of Mathematics, Purdue University
Coauthors: Professor Fabio Milner

More and more drug-resistant cases in epidemic diseases are reported by WHO and clinics these years. In addition, vaccination in some childhood diseases are not as effective as expected and the recurrence of certain epidemics seems likely. In this paper, we assume that the recovery period for drug-resistant cases or infection after vaccination is harder and longer, and the vaccination is not fully and permanently protective; we find that the backward bifurcation is very likely and this may explain why some epidemics come back after disappearing for several years.

Date received: September 1, 2007