When we were kids, my elder brother had all sorts of child stuff like measles, chickenpox and so.
My mom used to put us in hte same room to play, so I could also get the illness in due time (i.e. during childhood).
Don't know exactly why but it never worked. Bad grass, there is some french saying about that
My son started a path quite similar to mine: went through 4 epidemias at school without a single simptom.... obviously that was only to start with : I had to get him out from school because some of these red spots had appeared during the morning.
So rushing to the doctor and then locked back home during a whole week to take care of the little one...
Will I get it? Suspense