It is possible to get chickenpox even after taking chickenpox vaccine, which may be related to the following two points. 1. The probability of producing antibodies: under normal circumstances, after receiving chickenpox vaccine, the antigen enters the body and stimulates the immune system to produce specific antibodies from the immune response, but the probability of producing antibodies is not 100%. However, the probability of producing antibodies is not 100%. If the immune response of the subject is not good at the time of vaccination, there may be cases where sufficient antibodies cannot be produced or even no antibodies are produced. 2. The timeliness of the vaccine: the body will produce antibodies after receiving chickenpox vaccine, which can generally protect the human body for 5 to 10 years. The number of antibodies will slowly decrease with time, and the resistance to chickenpox virus will decrease, thus causing chickenpox. Even if the chickenpox vaccination does not produce antibodies satisfactorily, under the same conditions after being infected with the chickenpox virus, the subject’s symptoms are less severe than those of a person who has not received the chickenpox vaccine, and the recovery is relatively faster. Therefore, active vaccination against chickenpox is still necessary.