that is a good point, the numbers vary based on the vaccine, but there are a large number of people who either have violent reactions (even death) or the vaccine does not "take" so they can still get the illness that was meant to be prevented
also, even if you never get the vaccine, it is not a sure thing that you will catch that illness
this is why I am against the idea of mandatory vaccinations, it is about rick, you MIGHT get killed from the vaccine, you MIGHT never catch the illness even if unvaccinated
this is a world of difference from denying a child needed medical care
(sorry to get off topic, but I have heard a lot of people talk about mandatory vaccinations recently)