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Meta-Analysis
. 2017 Nov;75(5):381-394.
doi: 10.1016/j.jinf.2017.09.010. Epub 2017 Sep 18.

Effectiveness of influenza vaccines in preventing severe influenza illness among adults: A systematic review and meta-analysis of test-negative design case-control studies

Marc Rondy  1 , Nathalie El Omeiri  2 , Mark G Thompson  3 , Alain Levêque  2 , Alain Moren  4 , Sheena G Sullivan  5
Affiliations
Meta-Analysis

Effectiveness of influenza vaccines in preventing severe influenza illness among adults: A systematic review and meta-analysis of test-negative design case-control studies

Marc Rondy et al. J Infect. 2017 Nov.

Abstract

Objectives: Summary evidence of influenza vaccine effectiveness (IVE) against hospitalized influenza is lacking. We conducted a meta-analysis of studies reporting IVE against laboratory-confirmed hospitalized influenza among adults.

Methods: We searched Pubmed (January 2009 to November 2016) for studies that used test-negative design (TND) to enrol patients hospitalized with influenza-associated conditions. Two independent authors selected relevant articles. We calculated pooled IVE against any and (sub)type specific influenza among all adults, and stratified by age group (18-64 and 65 years and above) using random-effects models.

Results: We identified 3411 publications and 30 met our inclusion criteria. Between 2010-11 and 2014-15, the pooled seasonal IVE was 41% (95%CI:34;48) for any influenza (51% (95%CI:44;58) among people aged 18-64y and 37% (95%CI:30;44) among ≥65 years). IVE was 48% (95%CI:37;59),37% (95%CI:24;50) and 38% (95%CI:23;53) against influenza A(H1N1)pdm09, A(H3N2) and B, respectively. Among persons aged ≥65 year, IVE against A(H3N2) was 43% (95%CI:33;53) in seasons when circulating and vaccine strains were antigenically similar and 14% (95%CI:-3;30) when A(H3N2) variant viruses predominated.

Conclusions: Influenza vaccines provided moderate protection against influenza-associated hospitalizations among adults. They seemed to provide low protection among elderly in seasons where vaccine and circulating A(H3N2) strains were antigenically variant.

Keywords: Adults; Hospitalization; Influenza; Meta-analysis; Systematic review; Vaccine effectiveness.

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Conflict of interest statement

Conflict of interest

All authors declare no competing interests.

Figures

Figure 1
Figure 1
Flow chart for selection of studies. * References of retrieved articles
Figure 2
Figure 2
Study specific and pooled seasonal influenza vaccine effectiveness against any influenza by age group.
Figure 3
Figure 3
Study specific and pooled seasonal influenza vaccine effectiveness against influenza A(H1N1)pdm09 by age group.
Figure 4
Figure 4
Study specific and pooled seasonal influenza vaccine effectiveness against influenza A(H3N2) by age group.
Figure 5
Figure 5
Study specific and pooled seasonal influenza vaccine effectiveness against influenza B by age group.
Figure 6
Figure 6
Funnel plots of effect size of individual studies included in the meta-analysis of influenza vaccine effectiveness against any influenza among adults all ages, 18–64 years and 65 years and older. Points correspond to OR from individual studies, diagonal lines show the expected 95% confidence intervals around the summary estimate. Odds ratios are plotted on a logarithmic scale.
See this image and copyright information in PMC

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