SIR model Ap number of births Birth---- Leaving susceptible (S) XSLrS: Susceptible Infected ▣λsl,t=infection rate ▣vt=vaccination rate ViSt ▣λds=death rate of S Recovered AdsSt Xdlt Death Bhattacharya,Hyde and Tu-HealthEconomics Bhattacharya, Hyde and Tu – Health Economics SIR model  Λb = number of births  Leaving susceptible (St )  λSI,t = infection rate  vt = vaccination rate  λdS = death rate of S