It's irrelevant what happened when she got the shot. It doesn't matter.

You should wear a condom.

As far as most of us guys that have a girl/wife. A lot of us are in committed relationships, which is not the same as just having sex with 'a friend'. And even then, there are some that still wear a condom anyway, more so as birth control then a barrier against STD's.

__________________
Put me on wheels and I'll turn tricks.

Clever? Nah, I ran out of that years ago. But if you find this, let me know, k?
"The road goes ever on..." ~ Tolkien

In memory of my friend skip...
Go then, there are other worlds than these