SIR model Ap number of births Birth------ Leaving susceptible (S) ASIS Susceptible Infected ▣λsl,t=infection rate ▣Vt=vaccination rate ViS: ▣入ds=death rate of S Leaving infected (I) Recovered ▣r=recovery rate Ad St ▣λd=death rate of I d月 Death- Bhattacharya,Hyde and Tu-HealthEconomicsBhattacharya, 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  Leaving infected (It )  λIR = recovery rate  λdI = death rate of I