Just want to chip in again to say that one shouldn't assume otherwise healthy children won't be at risk of complications from chickenpox.
My DD is a strong, healthy child who hasn't missed a day at school since she started last year. And yet here we are, day 10 in hospital, all because of the complications that arose from her (extremely mild) bout of chickenpox.
I assumed that, because she was strong and healthy, the swelling on her face couldn't be anything serious, as the sources I consulted implied that it was mostly those children with a compromised immune system were really at risk.
However, despite a doctor's diagnosis that suggested nothing serious was wrong, I expressed my concerns here on mumsnet and was strongly encouraged to get DD to A&E. Thank god I did, because had I left her sleeping in her bed that evening she could well have ended up in intensive care. As it was, she was very ill indeed.
People - myself included - just don't realise that when complications do arise they can be absolutely debilitating, even life threatening. We are not made aware of the danger signs to look out for.
I was talked out of getting DD vaccinated against CP by our doctor a few months ago. I truly wish I had stood my ground.