Vaccines as a Positive Externality

A science-based example of a positive externality is vaccinations. Vaccinations work based on the number of people in the population who are vaccinated. Once a certain threshold is reached, the disease can't spread effectively and is essentially eliminated. As long as enough people are vaccinated, others who choose not to be still get to enjoy that positive externality at no cost. These are what economists call freeloaders. Economists like the golden rule: Do unto others as you would have the...