thanks 
I ask because I have recently gone through an interesting situation with my step children as they head off to uni.
I advised my dss that he shoudl check his mmr status, as the mumps part in particular has been shown to wear off (hence a lot of the uni mumps outbreaks)
he, of course, convinced of the invincibility of youth, has not done so.
it is entirely up to him, he is an adult.
but it got me thinking about what I owuld have done/felt if he were my son. of course, I could have done nothing, in practical terms. and the worry is the same, as I care about him deeply.
but the fact remains that he is probably no longer immune to mumps, at a time when he really needs to be. and the whole thing got me wondering - I was as guilty as the next person when a teen of ignoring sensible advice form my parents becuas ehtey were just boring old worry-warts. and I owuld probably done exactly as he did - listened, and then carried on as normal, because it owuld never happen to me, right?
and I htink children/teens are in a funny cross-over place re: vaccines and diseases. they have the older generations mostly having lived thorught he typical childhood illnesses, yet vaccines being introduced for them now. and I think it must be hard for them to know what ot do about it all.