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. 2021 Jun 1;9(6):582.
doi: 10.3390/vaccines9060582.

Efficacy and Safety of COVID-19 Vaccines in Phase III Trials: A Meta-Analysis

Haoyue Cheng  1   2 , Zhicheng Peng  1   2 , Wenliang Luo  1   2 , Shuting Si  1   2 , Minjia Mo  1   2 , Haibo Zhou  1   2 , Xing Xin  1   2 , Hui Liu  3 , Yunxian Yu  1   2
Affiliations

Efficacy and Safety of COVID-19 Vaccines in Phase III Trials: A Meta-Analysis

Haoyue Cheng et al. Vaccines (Basel). .

Abstract

Nowadays, the vaccination with COVID-19 vaccines is being promoted worldwide, professionals and common people are very concerned about the efficacy and safety of COVID-19 vaccines. No published systematic review and meta-analysis has assessed the efficacy and safety of the COVID-19 vaccines based on data from phase III clinical trials. Therefore, this study has estimated the efficacy and safety of COVID-19 vaccines and the differences between vaccine types. PubMed, Embase, the Cochrane Library, CNKI, Wanfang, medRxiv databases and two websites were used to retrieve the studies. Random-effects models were used to estimate the pooled efficacy and safety with risk ratio (RR). A total of eight studies, seven COVID-19 vaccines and 158,204 subjects were included in the meta-analysis. All the vaccines had a good preventive effect on COVID-19 (RR = 0.17, 95% CI: 0.09-0.32), and the mRNA vaccine (RR = 0.05, 95% CI: 0.03-0.09) was the most effective against COVID-19, while the inactivated vaccine (RR = 0.32, 95% CI: 0.19-0.54) was the least. In terms of safety, the risk of overall adverse events showed an increase in the vaccine group after the first (RR = 1.46, 95% CI: 1.03-2.05) or second (RR = 1.52, 95% CI: 1.04-2.20) injection. However, compared with the first injection, the risk of local (RR = 2.64, 95% CI: 1.02-6.83 vs. RR = 2.25, 95% CI: 0.52-9.75) and systemic (RR = 1.33, 95% CI: 1.21-1.46 vs. RR = 1.59, 95% CI: 0.84-3.01) adverse events decreased after the second injection. As for the mRNA vaccine, the risk of overall adverse events increased significantly, compared with the placebo, no matter whether it was the first (RR = 1.83, 95% CI = 1.80-1.86) or the second (RR = 2.16, 95% CI = 2.11-2.20) injection. All the COVID-19 vaccines that have published the data of phase III clinical trials have excellent efficacy, and the risk of adverse events is acceptable. The mRNA vaccines were the most effective against COVID-19, meanwhile the risk and grade of adverse events was minimal, compared to that of severe symptoms induced by COVID-19.

Keywords: COVID-19; efficacy; meta-analysis; safety; vaccine.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Flow diagram showing the progress through the stages of meta-analysis.
Figure 2
Figure 2
Overall risk of bias assessment using the Cochrane tool and risk of bias assessment by individual trials. (A) Overall risk of bias assessment using the Cochrane tool. (B) Risk of bias assessment by individual trials.
Figure 3
Figure 3
Meta-analysis of efficacy of vaccine between vaccine and placebo groups by type of vaccine (from 7/14 days after dose 2).
Figure 4
Figure 4
Meta-analysis of efficacy of vaccine between vaccine and placebo groups by type of vaccine (from 7/14 days after dose 1).
Figure 5
Figure 5
Meta-analysis of effect of vaccine on overall adverse events between vaccine and placebo groups after dose 1.
Figure 6
Figure 6
Meta-analysis of effect of vaccine on overall adverse events between vaccine and placebo groups after dose 2.
Figure 7
Figure 7
Meta-analysis of effect of vaccine on serious adverse events between vaccine and placebo groups by type of vaccine.
See this image and copyright information in PMC

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