There are several theories that could explain how someone might get chickenpox more than once. Some examples are explained below.
• Many medical professionals believe that the person’s condition was misdiagnosed first time around, and that they had another condition with similar symptoms.
• There may be a genetic link. In the US studies mentioned above, around half of the people who reported having chickenpox before said that other members of their family had also had chickenpox more than once.
• There may be more than one strain of the chickenpox virus. If this is the case, it may be possible for someone to be infected by a different strain each time. However, there is no scientific evidence to support this theory.