Effectiveness of Two-dose Varicella Vaccination: Bayesian Network Meta-analysis

Purpose: A 2-dose varicella vaccination strategy has been introduced in many countries worldwide, aiming to increase vaccine effectiveness (VE) against varicella infection.In this network meta-analysis, we aimed to provide a comprehensive evaluation and an overall estimated effect of varicella vaccination strategies, via a Bayesian model.Methods: For each eligible study, we collected trial characteristics, such as: 1-dose vs. 2-dose, demographic characteristics, and outcomes of interest.For studies involving different doses, we aggregated the data for the same number of doses delivered into one arm.The preventive effect of 1-dose vs. 2-dose of varicella vaccine were evaluated in terms of the odds ratio (OR) and corresponding equal-tailed 95% confidence interval (95% CI).Results: A total of 903 studies were retrieved during our literature search, and 25 interventional or observational studies were selected for the Bayesian network metaanalysis.A total of 49,265 observed individuals were included in this network meta-analysis.Compared to the 0-dose control group, the OR of all varicella infections were 0.087 (95% CI, 0.046-0.164)and 0.310 (95% CI, 0.198-0.484)for 2-doses and one-dose, respectively, which corresponded to VE of 69.0% (95% CI, 51.6-81.2) and VE of 91.3% (95% CI, 83.6-95.4) for 1-and 2-doses, respectively.Conclusions: A 2-dose vaccine strategy was able to significantly reduce varicella burden.The effectiveness of 2-dose vaccination on reducing the risk of infection was demonstrated by sound statistical evidence, which highlights the public health need for a 2-dose vaccine recommendation.