TripleJ - Thats one reason I haven't vaxed. When MIL was a kid she pent alot of time in hospital. At one point she snuck into isolation & was in contact with CP. Slowly kids out of isolation contracted CP, but she never did.

We talked about this when DD2 had her bout of it. Being only 6 months old I assumed DD1 must've brought it home from pre school. But DD1 never showed any symptoms of it herself. Possibly a cold/temp etc, but I don't remember now...

When SIL was younger, she also never contracted CP, even though MIL often had her around kids with CP (yes, kind of a pox party thing ). She's now 18 & has never had CP or the vax that we know of (given you can contract but not show all symptoms, eg. spots)

DS was playing with a little boy just 3 or 4 days before he broke out in spots. DS didn't catch it either.

So while I obviously don't know for certain that this is whats happened, I'm assuming the kids have possibly inherited a gene or something that prevents them contracting it, or for some reason just not showing symptoms. MIL described herself as a carrier.

I don't know if that makes sence to anyone else, but I think there's a pretty good chance my kids don't need the vaccine

It probably sounds as nuts & as stupid as the look I got from my CHN when I tried to explain it to her, but thats my story & I'm sticking to it for now. Until proven otherwise.