My mother, 55yrs old, had chicken pox infection in childhood, same as every child has in summer vacations. 5yrs back she was detected with breast cancer. She had undergone surgery, chemotherapy and radiation therapy for the same. She is doing fine now. Since 2 days she was taking care of my adult sister who has chicken pox infection. Now is my mother prone to infection once again or will her childhood immunity be effective even after chemotherapy.