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Review
. 2021 May 6;9(5):467.
doi: 10.3390/vaccines9050467.

Efficacy and Safety of COVID-19 Vaccines: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

Ali Pormohammad  1 , Mohammad Zarei  2 , Saied Ghorbani  3 , Mehdi Mohammadi  1 , Mohammad Hossein Razizadeh  3 , Diana L Turner  4 , Raymond J Turner  1
Affiliations
Review

Efficacy and Safety of COVID-19 Vaccines: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

Ali Pormohammad et al. Vaccines (Basel). .

Abstract

The current study systematically reviewed, summarized and meta-analyzed the clinical features of the vaccines in clinical trials to provide a better estimate of their efficacy, side effects and immunogenicity. All relevant publications were systematically searched and collected from major databases up to 12 March 2021. A total of 25 RCTs (123 datasets), 58,889 cases that received the COVID-19 vaccine and 46,638 controls who received placebo were included in the meta-analysis. In total, mRNA-based and adenovirus-vectored COVID-19 vaccines had 94.6% (95% CI 0.936-0.954) and 80.2% (95% CI 0.56-0.93) efficacy in phase II/III RCTs, respectively. Efficacy of the adenovirus-vectored vaccine after the first (97.6%; 95% CI 0.939-0.997) and second (98.2%; 95% CI 0.980-0.984) doses was the highest against receptor-binding domain (RBD) antigen after 3 weeks of injections. The mRNA-based vaccines had the highest level of side effects reported except for diarrhea and arthralgia. Aluminum-adjuvanted vaccines had the lowest systemic and local side effects between vaccines' adjuvant or without adjuvant, except for injection site redness. The adenovirus-vectored and mRNA-based vaccines for COVID-19 showed the highest efficacy after first and second doses, respectively. The mRNA-based vaccines had higher side effects. Remarkably few experienced extreme adverse effects and all stimulated robust immune responses.

Keywords: COVID-19; SARS-CoV-2; efficacy; meta-analysis; randomized clinical trial; side effect; vaccines.

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Conflict of interest statement

The authors declare no competing interest. The author(s) declare no competing financial interests.

Figures

Figure 1
Figure 1
Flow diagram of literature search and study selection for meta-analysis (PRISMA flow chart).
Figure 2
Figure 2
Efficacy of different COVID-19 vaccines (a) after the first and (b) second doses.
Figure 2
Figure 2
Efficacy of different COVID-19 vaccines (a) after the first and (b) second doses.
Figure 3
Figure 3
Local and systemic side effects of different COVID-19 vaccines.
Figure 4
Figure 4
Association of adjuvant side effects of different COVID-19 vaccines.
See this image and copyright information in PMC

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