When students start school, they have to prove that they were vaccinated against diseases such as chicken pox, polio, and measles, which can spread quickly through an unprotected group. Students with compromised immune systems can be exempted from the requirement because the immunizations might be dangerous to them. In most states, parents also can get exemptions based on personal beliefs.

California Senate Bill 277, passed in 2015, eliminated personal-belief exemptions. The law was prompted by a measles outbreak that started at Disneyland in 2014 and infected more than 150 people. That outbreak was likely exacerbated by low vaccination rates.

California's law sought to remove personal-belief exemptions to increase vaccination rates and herd immunity, a form of indirect protection that occurs when a large percentage of a population has become immune. Herd immunity helps protect people who, because of medical reasons, cannot be vaccinated and are vulnerable to infections. It seems to have worked. The percentage of California's kindergartners with all required vaccinations rose from 93 percent in fall 2014 to 96 percent in fall 2016 (Lin 2017).

Not everyone supported Senate Bill 277. The president of A Voice for Choice, a group that opposed the bill, was quoted as saying, "It's not right for children to be prevented from going to school because of their vaccination status" (Siripurapu 2016). This opinion appears to be a minority view, as a referendum to repeal the law got too few signatures to make the ballot. "It's going to ensure that all children are safe in school from dangerous, preventable diseases," said state senator Richard Pan, the bill's author (Siripurapu 2016).

Discussion Questions

What are the external effects of a vaccine?

Are people who rely solely on herd effects free riders?

What are the scientifically verified potential harms of vaccines?

What are the possible health outcomes of chicken pox, polio, and measles?

What are the external effects of these diseases?

Have vaccination rates risen or fallen in the United States?

Would too few people be vaccinated if it were not mandatory? Is there evidence?

Are vaccination rates lower in states with personal-belief exemptions?

What steps do governments take to increase vaccination rates?

What steps do private companies take to increase vaccination rates? Why?