When a person gets an influenza vaccine, he or she is less
likely to get sick with the flu. This makes it less likely for that
person to pass the flu to someone else. Suppose that the external
benefit created by the influenza vaccination is equal to $100 per
dose.
(a) In a diagram, show the equilibrium in the influenza vaccine
market. Also, show the quantity that would maximise social surplus.
Is this equal to the perfectly competitive market equilibrium...