Figure 2

Comparison of models: Varying cross-immunity and delay for introducing strain. 2 Comparison of results from network model for one age class (top row), two age classes (middle row), and mean field (bottom row) models. Solid curves are for δ = 0.4 (60% cross-immunity) and dashed curves for δ = 0.9 (10% cross-immunity). Plots in the left column are for the appearance of the second strain 10 days after strain-1 infection starts; right column plots for the appearance of the second strain 60 days after initial strain-1 infection. For both network models, strain 1 was introduced into class k = 5 and strain 2 into class k = 10. For the two age class model, infections were started in different age classes. Note that a second wave appears only when the cross-immunity is small (dashed curves), apart from a small, delayed outbreak in the one-age class model.