biostudies-literatureZhang ZBeijing Natural Science Foundation543https://www.ebi.ac.uk/biostudies/studies/S-EPMC8188742biostudies-literatureUnknown21(1)<h4>Background</h4>The objectives of this review were to evaluate the vaccine effectiveness (VE) of the two-dose varicella vaccine for healthy children in China and explore the application of the approach of Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) in observational studies on VE.<h4>Methods</h4>We searched for observational studies on two-dose varicella VE for children in China aged 1-12 years that were published from 1997 to 2019, and assessed the quality of each study using the Newcastle Ottawa Scale (NOS). We used meta-analysis models to obtain the pooled two-dose VE, and the studies were divided into subgroups and analysed according to whether or not it was an outbreak investigation and its NOS score. The quality of evidence of VEs were rated by approacBMC infectious diseasesTwo-dose varicella vaccine effectiveness in China: a meta-analysis and evidence quality assessment.PMC8188742L202008Suo LLu LPan JZhang ZZhao DfalseTwo-dose varicella vaccine effectiveness in China: a meta-analysis and evidence quality assessment.<h4>Background</h4>The objectives of this review were to evaluate the vaccine effectiveness (VE) of the two-dose varicella vaccine for healthy children in China and explore the application of the approach of Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) in observational studies on VE.<h4>Methods</h4>We searched for observational studies on two-dose varicella VE for children in China aged 1-12 years that were published from 1997 to 2019, and assessed the quality of each study using the Newcastle Ottawa Scale (NOS). We used meta-analysis models to obtain the pooled two-dose VE, and the studies were divided into subgroups and analysed according to whether or not it was an outbreak investigation and its NOS score. The quality of evidence of VEs were rated by approac2021-01-01T00:00:00Z2021 Jun2025-04-18T21:04:28.088Z2022-02-10T14:28:10.284ZS-EPMC81887423410789110.1186/s12879-021-06217-1