The market for flu vaccinations Social demand curve Dsoc is greater than the private demand Curve Dpriv Captures positive B externality of herd P S immunity Dsoc Dpriv Socially efficient equilibrium higher Q than private equilibrium Bhattacharya,Hyde and Tu-HealthEconomicsBhattacharya, Hyde and Tu – Health Economics The market for flu vaccinations  Social demand curve Dsoc is greater than the private demand curve Dpriv  Captures positive externality of herd immunity  Socially efficient equilibrium higher than private equilibrium