Unfortunately, it's not that simple. Maybe 95% of the people who get vaccinated are subsequently immune, the rest (and people who have depressed immune systems

Unfortunately, it's not that simple. Maybe 95% of the people who get vaccinated are subsequently immune, the rest (and people who have depressed immune systems) are dependent on herd immunity. So the small number who choose not to vaccinate can make life much more dangerous for the few who can't or for whom the vaccination was ineffective. For a good look at the maths, see this blog post: http://www.goodmath.org/blog/2015/02/05/quick-vaccine-math/ http://www.goodmath.org/blog/2015/02/05/quick-vaccine-math/