Although it usually causes no long-standing complications in the vast majority of patients, for those in whom complications do occur, the consequences can be severe.
Most people already know that it is unusual for someone to get chickenpox twice.
That's because the first time you get the infection, your body's immune system is dealing with something it's never seen before, and it takes some time for it to figure out the best way to respond. Once your body has developed a defense, it retains some memory of how to respond in order to counter any future infection attempts by the virus. However, because the vaccine version of the virus is weaker, the immune system is able to overcome it much more readily, and most children don't get sick. Despite the fact that the child avoids all the discomfort, itching and fever that we typically associate with chickenpox, his body still learns enough to be able to guard against any future infections. A child given the vaccine has a 70 to 80 percent chance of not getting chickenpox at all.