One must also remember, that in order for your vaccinations to work, your body actually has to receive the virus. ie it can't fight it off until it is in your body.
So technically, Yes you have to catch it before your immune system can do it's thing.
I am so tired of the comments that , Oh you can still catch it if you're vaccinated. Well duh. Same goes for passing it on (until your body destroys it)
