Consistent with the model of the previous section, there are a series of epidemic
outbreaks (Fig. 21.11). Due to the additional features of this model, however, the
numbers of immune and nonimmune people tends to rise as does the number of
sick. This rise is due to the differences between the birth and death rates.
Introduce a spatial component into the model by considering two regions with
different contact rates and different vaccination programs. Investigate the implications of travel restrictions imposed by one of the regions on people originating in
the other region.
Fig. 21.9
21.7 Epidemic with Vaccination
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