It is necessary to have two doses of chickenpox vaccine, because with only one dose of chickenpox vaccine, there is still a relatively large percentage of people who are not well protected against chickenpox. With the extension of the first varicella vaccination, after 6 or 7 years, it is very likely that a person will contract varicella when he or she comes into contact with a person with chickenpox or shingles again. If a second vaccination is given, that is, a booster shot, this part of the population can obtain a longer-lasting immunity to the chickenpox virus, and the possibility of getting chickenpox in the future should be lower, so it is necessary to receive the chickenpox vaccine twice. Some people may have a mild fever after each varicella vaccination. If you have a feverish reaction and your body temperature is not high, you do not need to worry too much. Only if your body temperature is particularly high and your accompanying symptoms are obvious, you need to go to the hospital for treatment.