“…Specifically, the dynamics of the population are driven by the non‐null infinitesimal rates and q ( i , j ),( i , j ) = − q ( i , j ) with for . By conveniently labeling states, (1) results in distinct level‐dependent quasi‐birth‐death (LD‐QBD) processes, which are used by Gómez‐Corral and López‐García(, Section 3.2) to provide the sensitivities and elasticities of first‐passage times and hitting probabilities, extreme values, and stationary measures of either an outbreak of the disease or the outbreak of the type‐ k strain, for k ∈ {1,2}.…”