EXISTENCE OF PERIODIC SOLUTIONS OF SEASONALLY FORCED SIR MODELS WITH IMPULSE VACCINATION

In this paper, we study periodic oscillation of seasonally forced epidemiological models with impulse vaccination where periodicity occurs in contact rate. Using the famous Mawhin's coincidence degree method, we get the existence of positive periodic solutions of seasonally forced SIR models with impulse vaccination at fixed time. Some numerical simulations are presented to illustrate the effectiveness of such pulse vaccination strategy.