I personally do not get vaccinations, for many reasons. In some cases yes they are good for you and you need them, it depends on how your immune system is. However, if you have a really good immune system then it is a waste of money, time, and possibly could harm you. There has been countless cases of people who get a vaccination turn up with whatever the vaccination was suppose to keep them from having.
In general when you get a vaccination you are injecting a small amount of the virous into your body. Your body then attacks the small amount and makes an antidote.
Some people react badly to this small amount of the virous. Their body takes longer to attack it giving it time to reproduce. That is why some people actually get sick from a vaccination.
Then you have people who even though they got the vaccination they still get the virous, it doesn't always work.