I'm sure this is very common.
Ds keeps getting exposed to chickenpox but can't seem to catch it.
First time (that I know of obv) was about a year ago when he played with a friend about 3 days before her spots came out and was sharing snacks etc so pretty close contact.
Then there was a nursery outbreak.
Then his older cousin got it, although contact was towards the end of the infectious period.
Then his younger cousin got it, and he was fighting over toys with her the day she started feeling grumpy (spots next day).
Now there's another nursery outbreak but no sign of pox on the boy so far.
He's only 2.6 so plenty of time and I suppose we get exposed all the time as children and I didn't succumb until 10, but as time off will be a bit of a mare every time I think there's a chance of him getting it I start planning and then it comes to nowt!