Suppose that a vaccine is developed for a highly contagious strain of flu. The likelihood that anyone will get this flu decreases as more people receive the vaccine.
a. Private incentives will lead to ______ people receiving the vaccine at a cost of ___.
b. If the flu vaccine is provided by private markets, deadweight loss will be ________.
c. The socially optimal number of vaccines is _____. This externality could most effectively be corrected by _______________________.