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Meta-Analysis
. 2021 Oct;26(41):2100920.
doi: 10.2807/1560-7917.ES.2021.26.41.2100920.

Effectiveness of COVID-19 vaccines against SARS-CoV-2 infection with the Delta (B.1.617.2) variant: second interim results of a living systematic review and meta-analysis, 1 January to 25 August 2021

Thomas Harder  1 , Wiebe Külper-Schiek  1 , Sarah Reda  1 , Marina Treskova-Schwarzbach  1 , Judith Koch  1 , Sabine Vygen-Bonnet  1 , Ole Wichmann  1
Affiliations
Meta-Analysis

Effectiveness of COVID-19 vaccines against SARS-CoV-2 infection with the Delta (B.1.617.2) variant: second interim results of a living systematic review and meta-analysis, 1 January to 25 August 2021

Thomas Harder et al. Euro Surveill. 2021 Oct.

Abstract

The Delta variant has become the dominant strain of SARS-CoV-2. We summarised the evidence on COVID-19 vaccine effectiveness (VE) identified in 17 studies that investigated VE against different endpoints. Pooled VE was 63.1% (95% confidence interval (CI): 40.9-76.9) against asymptomatic infection, 75.7% (95% CI: 69.3-80.8) against symptomatic infection and 90.9% (95% CI: 84.5-94.7) against hospitalisation. Compared with the Alpha variant, VE against mild outcomes was reduced by 10-20%, but fully maintained against severe COVID-19.

Keywords: COVID-19; Delta variant; SARS-CoV-2; systematic review; vaccination; vaccine effectiveness; variant of concern.

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Conflict of interest statement

Conflict of interest: None declared.

Figures

Figure 1
Figure 1
Results of the meta-analysis for SARS-CoV-2 infection outcomes, 1 January–25 August 2021
Figure 2
Figure 2
Results of the meta-analyses for symptomatic infection and hospitalisation stratified by vaccine, 1 January–25 August 2021
See this image and copyright information in PMC

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