Figure 5
From: Impact of viral drift on vaccination dynamics and patterns of seasonal influenza
Patterns of seasonal epidemics for 12 seasons in the absence of vaccination. Colorbar represents the total number of infections for each season, and m 1 is the duration of immunity induced by natural infection. Duration of immunity induced by natural infection is (a) m 1 = 4; (b) m 1 = 6; and (c) m 1 = 8 years. Other parameter values are given in Table 1.