Acellular pertussis vaccine efficacy: An updated systematic review and meta -analysis.

Recent studies indicate an increased incidence of pertussis disease in recent years. The aim of this study was to evaluate the efficacy of the acellular vaccine for children (as a replacement of current whole cell vaccine in the Expanded Program on Immunization) and for high-risk adults in Iran through updating current best available evidence. We performed a systematic literature review in relevant databases we focused on previously published systematic reviews to select those that address our questions. The AMSTAR (assessing the methodological quality of systematic reviews) tool was used for screening available reviews. Then search in databases was done until Feb 2014 to update the evidence. We pooled results using meta-analysis methods by Stata statistical package. Eleven systematic review articles were included in the initial evaluation. In the end, two systematic reviews on acellular vaccine booster doses and the acellular vaccine in children were selected as the baseline evidence. In the update phase, new clinical trials were screened, and the results were updated. Overall pooled estimate of relative efficacy of acellular to whole cell was 0.68 (95% CI, 0.55-0.81) for children immunization Pooled estimates for the efficacy of acellular versus placebo were 0.70 (95% CI, 0.60-0.80). Overall pooled estimate of efficacy of booster dose of acellular was 0.87(95% CI, 0.85-0.88) compared to placebo. In addition pooled estimate of acellular vaccine efficacy based on response to antigen was 0.78(95% CI, 0.64-0.93) in highrisk group. The results show higher performance and safety of the acellular vaccine in the prevention of pertussis in children versus the whole cell vaccine. Moreover, the efficacy of the acellular vaccine in high-risk adult groups is acceptable. This study provides evidence in favor of the introduction of an acellular vaccine to the national program of immunization. Studies on cost effectiveness and aspects of policy analysis are recommended.