The American Academy of Pediatrics and the Centers for Disease Control recommend the vaccine for children 12 months of age and older who have not already had chickenpox. Children 13 years of age and older need two doses.
The chickenpox vaccine is thought to be safe for healthy children. Side effects of the shot are minimal -- mild fever, rash, or pain at the injection site for a small minority of patients. The vaccine is effective for more than 95 percent of the children who get it, and this protection lasts 10 years or longer. The benefits of the vaccine include less medical complications, less health costs (parents and caregivers won't miss work), and less exposure to the natural disease for the adults and children who couldn't handle it well. There are arguments against giving it to all children: chickenpox is still a benign illness for most children; we don't know whether a child will have a lifelong immunity to the disease from the vaccine; and chickenpox in adults is more severe. It is not known right now whether a booster shot will be recommended in the future.
My wife and I have given the chickenpox vaccine to both our kids and I do recommend it for healthy children in my practice. So what should you do? I suggest you further discuss the pros and cons with your child's doctor. Together, you'll be better able to make an informed decision that makes you comfortable.