It’s been quite a few years, because my CAH daughter is 14 now, but when she was about 6 she got the chicken pox.  My pediatrician had given me a prescription for Zovirax and told me to start her on it with 24 hours of the first sign.  I did and it caused her to have a much milder case - enough to give immunity, but not severe enough to cause problems.  Do they give the vaccine to kids with CAH?  I know the vaccine was first available in the US a year or two after Kristin had already had chicken pox.  I do know that she has never had the pertussis/whooping cough vaccine because the pediatrician said that she should not because of the steroids.  We had to get a dr’s note about it before she could start school in our county.