Fig. 1

The SEIR model. Individuals in the susceptible compartment (S) progress along the exposed compartment (E), infective compartment (I), and recovered compartment (R) at per capita rates λ, θ, and α, respectively, once they are infected with influenza. The subscript, W, W1, W2, and V, specifies the transition process involving each respective clade/strain. Individuals pass from compartment S directly into compartment R 15 days after receiving influenza vaccination at a proportion of ν according to the program agenda (see Additional file 5: Table S4). a Model for single-clade influenza season. b Model for two-clade influenza season. The model applied to each age group as well as the whole population