No, you still don’t got it.
You get a vaccination. Yay! It will reduce the chances that you’ll get the disease. Reduce. Not eliminate. Reduce.
So then I get vaccinated. Yay! It will reduce the chances that I’ll get the disease or that I’ll pass it to you. Reduce, not eliminate.
So now **curlcoat **doesn’t get vaccinated. She goes to Germany and gets measles, but before she gets symptoms, we pass her in the produce section and she coughs on us.
Ooops! We’ve only reduced, not eliminated, our risk of catching it from her. Like most people that have been vaccinated, I don’t get it, nor do I pass it on to you.
You aren’t so lucky. Your vaccine reduced, but didn’t eliminate your chances of catching it. You got it, and you’re dead. Or meningitis or pneumonia or hepatitis (all potential complications of measles, more common in adults than children) or if you’re really lucky, you just miss two weeks of work and income feeling like crap.
That’s herd immunity in a nutshell. Vaccines are effective, but not quite 100% effective. Add up a bunch of not-quite-100% effectives, and some of us who were vaccinated *will *get sick, just like some number of people will get pregnant each year despite using 98% effective birth control pills.