EFFECTS OF VACCINATION PROGRAMS ON TRANSMISSION RATES OF INFECTIONS AND RELATED THRESHOLD CONDITIONS FOR CONTROL

This study addresses the problem of the existence of conditions for pe rsistence or eradication of age-dependent directly transmitted infecti ons. The usual system of differential equations describing the dynamic s of the disease is transformed into integral equations. The authors s how how to solve these equations and, by applying the contraction mapp ing theorem, give conditions for the persistence or eradication of the infection. A practical illustration of the application of the methods proposed is sketched, using data for rubella collected from a small B razilian community.