Overview of SEIR compartmental model.

The main compartments are denoted by S(t), E(t), I(t), and R(t) for susceptible, exposed, infected, and removed, respectively. Compartments are stratified by age class (1—children, 2—adults) and membership to cohort k. The coefficients α_kℓ ∈ [0, 1] account for the strength of interaction between cohorts k and ℓ.