Incidence of breakthrough varicella after the vaccination of live attenuated varicella vaccine: a Meta-analysis

Objective To evaluate the incidence of breakthrough varicella (BV) after the vaccination of live attenuated varicella vaccine (VarV),so as to optimize the strategy of VarV vaccination.Methods By searching data bases of China Biology Medicine disc,China National Knowledge Infrastructure,Wanfang Database,National Center for Biotechnology Information,random control trials (RCT) and cohort studies on the incidence of BV after 1 dose or 2 doses of VarV were included.Pooled estimate of the incidence of BV was calculated.Subgroup analyses and meta-regression were used to detect the risk factors of the heterogeneity.Results A total of 20 original articles were included.The pooled average BV incidence after 1 dose of VarV was 12.4/1 000 person years (PY)(95%CI:9.0-15.9) and was 0.2/1 000PY (95%CI:-0.2-0.6) in the individuals after 2 doses.The incidence of BV was 11.0/1000 PY (95CI%:5.8-16.1) within 3 years after the first dose,and increased to 15.7/1000 PY(95CI%:8.3-23.0) after 5 years.The meta-regression showed that design type,age at vaccination and the follow-up time accounted for approximately 75.3% of the heterogeneity in the average BV incidence rate after 1 dose.Conclusions The incidence of BV is lower among individuals after 2 doses than those after 1 dose of VarV.The interval of 3-4 years between the first and second vaccinations is recommended.