Meta-Analysis
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Meta-Anal. Jun 26, 2015; 3(3): 151-162
Published online Jun 26, 2015. doi: 10.13105/wjma.v3.i3.151
Effectiveness of 7-valent pneumococcal conjugate vaccine: A meta-analysis of post-marketing studies
Chiara de Waure, Maria Lucia Specchia, Silvio Capizzi, Mufida Aljicevic, Milos Dujovic, Admir Malaj, Walter Ricciardi
Chiara de Waure, Maria Lucia Specchia, Silvio Capizzi, Walter Ricciardi, Institute of Public Health, Catholic University of the Sacred Heart, 00168 Rome, Italy
Mufida Aljicevic, Faculty of Medicine, University of Sarajevo, 71000 Sarajevo, Bosnia and Herzegovina
Milos Dujovic, Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia
Admir Malaj, Faculty of Pharmacy, Medical University of Tirana, 1001 Tirana, Albania
Author contributions: All authors contributed to this work.
Conflict-of-interest: The authors have no conflicts of interest.
Data sharing: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Maria Lucia Specchia, MD, MPH, PhD, Institute of Public Health, Catholic University of the Sacred Heart, L.go F. Vito 1, 00168 Rome, Italy. marialucia.specchia@rm.unicatt.it
Telephone: +39-6-30154396 Fax: +39-6-35001522
Received: July 28, 2014
Peer-review started: July 30, 2014
First decision: December 17, 2014
Revised: April 22, 2015
Accepted: May 16, 2015
Article in press: May 18, 2015
Published online: June 26, 2015
Abstract

AIM: To investigate the 7-valent pneumococcal conjugate vaccine (PCV7) effectiveness.

METHODS: A systematic literature review of studies which evaluated the effectiveness of PCV7 vaccine was performed searching the keyword “heptavalent pneumococcal conjugate vaccine” in PubMed and Scopus until March 16, 2013. The selection of potential eligible articles was done by two researchers independently on the basis of abstract and title and only post-marketing studies were included in the systematic review. Data extraction was carried out by two researchers with respect to invasive pneumococcal diseases due to both all and vaccine serotypes in pre-vaccine and post-vaccine periods in children less than 5 years. Results of studies which were considered suitable for meta-analysis were combined by means of relative risk (RR) with 95%CI. Vaccine effectiveness was calculated as (1-RR) × 100. Heterogeneity was assessed by I2 and a random effects model was used to combine data in the case of heterogeneity. RevMan 5 was used to pool data.

RESULTS: On the whole, 757 eligible papers were identified from the literature search in PubMed and Scopus. Of them, 62 were finally considered in the systematic review and 38 were included in the meta-analysis. In all post-marketing studies included in the systematic review the incidence of invasive pneumococcal diseases due to vaccine serotypes declined significantly with the exception of few studies showing stability or a slight, but not significant, increase. Furthermore most of studies highlighted also a reduction in the incidence of invasive pneumococcal diseases due to all serotypes. With regards to meta-analysis, a random effects model was used to combine data because of the high heterogeneity. Data combination showed that the effectiveness of PCV7 in reducing invasive pneumococcal diseases due to vaccine serotypes and to all serotypes was 84% (95%CI: 74%-90%) and 53% (95%CI: 46%-59%) respectively. These results are confirmatory with respect to the efficacy of PCV7 against invasive pneumococcal diseases due to vaccine serotypes.

CONCLUSION: PCV7 implementation determines a significant decrease of invasive pneumococcal diseases.

Keywords: Streptococcus pneumoniae, Pneumococcal infections, Pneumococcal vaccines, Treatment outcome, Meta-analysis

Core tip: This systematic review and meta-analysis was performed with the aim to collect data from post-marketing studies on 7-valent pneumococcal conjugate vaccine (PCV7) and to provide evidence about the impact of the vaccine in the real world. Eligible articles were identified through a search on PubMed and Scopus. The meta-analysis showed that PCV7 is able to reduce invasive pneumococcal diseases due to both vaccine serotypes and to all serotypes. The effectiveness was 84% (95%CI: 74%-90%) and 53% (95%CI: 46%-59%) respectively. These data may be taken into consideration in order to foresee the impact under real conditions of PCV13 which has replaced PCV7 from 2010 onwards.