Asking the right question about vaccines

I've just read an excellent post on vaccines, by Ayla over at Primal Home.  When someone asks her, "Why don't you vaccinate?", she responds, "Why do you vaccinate?"

A long time ago, when I asked someone once why she didn't vaccinate, I got another very similar response.  It went something like this:

- Name the disease.
- Explain how one gets the disease.
- What's the prevalence of the disease where you live?
- What are the consequences of having the disease and what are the chances of having the most severe possible effects of the disease, assuming that a child is not malnourished and is living in fairly hygenic conditions?

Now,
- Name the vaccine for the disease.
- What other vaccines are in the same shot?
- What are the ingredients in the vaccine?
- What does the manufacturer's insert say about the side effects of the vaccine?
- What are the chances of a severe adverse reaction from the vaccine?

It was really only when I was able to answer these questions that I was able to answer the question of whether to vaccinate or not.