Inclusion Criteria:  Received one dose live attenuated varicella vaccine in the phase Ⅲ lot-consistency clinical trial; Guardian(s) of the volunteer should be capable of understanding the written - consent form, and such form should be signed before the children being included into this study.  Exclusion Criteria:  Received one dose live attenuated varicella vaccine at the end of the phase Ⅲ lot-consistency clinical trial; According to the investigator's judgment, the subject has any other factors that are not suitable for participating in the clinical trial.