There are people who can't be vaccinated, and instead depend on everybody near them being vaccinated so the disease can't spread to them, so leaving yourself unvaccinated
is not a risk only to yourself. I, for example, have a family history that means I can't take the usual meningitis vaccine. I am depending on the people around me getting vaccinated, and if they don't, they push
to me a risk of becoming infected, exactly like someone who doesn't wash their hands after using the restroom won't make
themselves any sicker but can infect
me.
http://www.slate.com/articles/news_and_politics/jurisprudenc...