Some parents refuse to get their children vaccinated against infectious diseases like measles and preventable infectious disease is returning to the developed world. A measles outbreak that began at California’s Disneyland has health officials warning of worse to come. Parents who don’t vaccinate are free riders.

a. Explain why someone in a rich country who has not opted out on medical or religious grounds and refuses to be vaccinated is a “free rider.”

b. The measles vaccine is highly effective. Were the people who got measles at Disneyland

“free riders”? Should vaccinations be compulsory?

Explain your answer.