Abstract

CONTEXT: 
Several varicella vaccines are available worldwide. Countries with a varicella vaccination program use 1- or 2-dose schedules.

OBJECTIVE: 
We examined postlicensure estimates of varicella vaccine effectiveness (VE) among healthy children.

DATA SOURCES: 
Systematic review and descriptive and meta-analysis of Medline, Embase, Cochrane libraries, and CINAHL databases for reports published during 1995–2014.

STUDY SELECTION: 
Publications that reported original data on dose-specific varicella VE among immunocompetent children.

DATA EXTRACTION: 
We used random effects meta-analysis models to obtain pooled one dose VE estimates by disease severity (all varicella and moderate/severe varicella). Within each severity category, we assessed pooled VE by vaccine and by study design. We used descriptive statistics to summarize 1-dose VE against severe disease. For 2-dose VE, we calculated pooled estimates against all varicella and by study design.

RESULTS: 
The pooled 1-dose VE was 81% (95% confidence interval [CI]: 78%–84%) against all varicella and 98% (95% CI: 97%–99%) against moderate/severe varicella with no significant association between VE and vaccine type or study design (P > .1). For 1 dose, median VE for prevention of severe disease was 100% (mean = 99.4%). The pooled 2-dose VE against all varicella was 92% (95% CI: 88%–95%), with similar estimates by study design.

LIMITATIONS: 
VE was assessed primarily during outbreak investigations and using clinically diagnosed varicella.

CONCLUSIONS: 
One dose of varicella vaccine was moderately effective in preventing all varicella and highly effective in preventing moderate/severe varicella, with no differences by vaccine. The second dose adds improved protection against all varicella.

Pediatrics, volume 137, issue 3 (no pagination), e20153741

Varicella