The chickenpox vaccine can be given twice in a lifetime, and after two injections, a person is basically immune to chickenpox for nearly the rest of his or her life. In the past, the chickenpox vaccine was given only once, usually 12 months after birth, and it prevented some people from getting chickenpox, but the statistics are not entirely consistent, with some close to 100% and some more than 70%. Therefore, two doses of chickenpox vaccine can have a better effect and make the probability of prevention close to 100%. Generally, after the first injection at 12-15 months, the second injection can be given after four weeks of age. If you have not had the vaccination before and have not had chickenpox, you can have two consecutive injections to achieve the effect, and the interval between these two injections is usually more than four weeks.