It was going round nursery when my son came out in a couple of sores, age 3.
At the time, though my daughter had already had it, with very impressive scars across her torso, she was undergoing a fourth round of intensive chemo for acute myeloid leukaemia, from which she died a few months later.
On hearing that my son had sores that resembled chickenpox, and she had been in contact with him the two weeks previously, she was placed in source isolation immediately, given drugs and my son was as well and vaccinated for good measure.
He has been titred and we will continue to titre him and booster as necessary.
Chickenpox killed two of my friends' children. It is only rare when it does not happen to you or your child.
People talk of 'nature's way', but nature's way killed more than a few children my parents, born in 1936 and 1941 respectively, breastfed and then fed a healthy, mostly vegetarian diet with plenty of exercise, knew. My aunt was a 'polio pioneer', a baby boomer among the first to be offered vaccine.
If you want to see how polio affected people, look at Mary Berry's left hand when she is cooking.
I don't get people who deliberately expose their children to illness, or, particularly, chickenpox.
You never see threads on here, 'Should I expose my child to influenza?'
MOST will do fine, but some will not, and indeed, some will die.
It is a risk. Life is.
But truly, for a little child? Deliberately?