It is still possible to get chicken pox with the chicken pox vaccine, but the incidence of chicken pox decreases significantly, not that the vaccine doesn’t work, but that no vaccine can prevent a disease 100%. If the chickenpox vaccine is given as a single injection, the possibility of getting chickenpox in the future still exists, and the likelihood of getting chickenpox increases over time. If a booster shot is given, i.e., a total of two shots, then the likelihood of getting chickenpox decreases more significantly. However, getting chickenpox again after receiving the chickenpox vaccine does not mean that the previous chickenpox vaccine was useless, because the condition of getting chickenpox again is usually slightly milder, and the symptoms of chickenpox are usually more severe if the chickenpox vaccine is not given.