Chickenpox vaccine only one shot and forget the second shot, you should go to the hospital in time to get the second shot. Chickenpox vaccine is mainly used to prevent the occurrence of chickenpox. It is usually given twice, the first injection after 1 year of age and the second injection after 4 years of age. If the first varicella vaccine is given after 4 years of age, there should be an interval of at least 3 months before the second shot is given. If you forget to take the second dose of chickenpox vaccine after only one dose, you should go to the hospital as soon as possible to take the second injection to avoid insufficient antibody production due to the long interval. Therefore, if you forget to take the second injection after taking only one chickenpox vaccine, it is recommended that you go to a regular hospital or immunization institution as soon as possible to take the second injection in order to enhance the protective ability of the chickenpox vaccine. If you do not take the second dose of chickenpox vaccine, resulting in insufficient chickenpox antibody production, you will be easily infected with chickenpox. Moreover, varicella antibodies usually last for about ten years, so as long as you are not older than 13 years old, you can get the second shot.