Zhu S, et al. - A meta-analysis is conducted to assess whether 2 varicella vaccine doses are needed in children and, if so, to determine the best time to vaccinate. Findings suggested two doses of varicella vaccine as more efficacious than a single dose. 3-4 years difference between the first and second vaccinations seemed to achieve higher efficacy.

Methods

• Researchers pooled the BV incidence rates after 1 or 2 doses of varicella vaccine using random effects, and estimated the risk factors after vaccination using 95% confidence intervals (CI).

Results

• This meta-analysis included 27 original articles.
• In children vaccinated with 1 dose, the pooled average BV incidence rate was 8.5 cases per 1,000 person years (PY) (95% confidence interval [CI], 5.3-13.7; random effects model) and in children vaccinated with 2 doses, it was 2.2 cases per 1,000 PY (95% CI, 0.5-9.3; random effects model).
• From the first to eighth year, the pooled trend of the annual BV incidence rate fluctuated, with a peak annual incidence rate of 35.3 cases per 1,000 population in the fourth year.
• The meta-regression suggested that design type, type of vaccine, and their interaction accounted for approximately 71.74% of the heterogeneity in the average BV incidence rate after 1 vaccine dose.