mRNA vaccines are the most effective against COVID-19

Objectives:
What are the efficacy and safety of COVID-19 vaccines and the differences between vaccine types?

Study design:
This review article included 8 RCTs with a total of 158,204 subjects.

The 8 RCTs provided data on 2 mRNA vaccines (mRNA-1273 and BNT162b2), 2 virus-vectored vaccines (ChAdOx1-S and Gam-COVID-Vac) and 3 inactivated vaccines (CoronaVac, HB02 and WIV04).

Results and conclusions:   
The investigators found all 7 vaccines had a good preventive effect on COVID-19 [RR = 0.17, 95% CI = 0.09 to 0.32].

The investigators found the mRNA vaccine [RR = 0.05, 95% CI = 0.03 to 0.09] was the most effective against COVID-19, while the inactivated vaccine [RR = 0.32, 95% CI = 0.19 to 0.54] was the least.  

The investigators found, 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 to 2.05) or second [RR = 1.52, 95% CI = 1.04 to 2.20] injection.

The investigators found, however, compared with the first injection, the risk of local [RR = 2.64, 95% CI = 1.02 to 6.83 vs. RR = 2.25, 95% CI = 0.52 to 9.75] and systemic [RR = 1.33, 95% CI = 1.21 to 1.46 vs. RR = 1.59, 95% CI = 0.84 to 3.01] adverse events decreased after the second injection.

The investigators found, 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 to 1.86] or the second [RR = 2.16, 95% CI = 2.11 to 2.20] injection.

The investigators found all the COVID-19 vaccines that have published the data of phase III clinical trials had excellent efficacy and the risk of adverse events was acceptable.

The investigators concluded that the 7 COVID-19 vaccines have excellent efficacy and safety. Among them, the mRNA vaccines are the most effective against COVID-19, while the risk of adverse events is also relatively the highest. Meanwhile, the efficacy of the inactivated vaccines is not as good as the mRNA vaccines, while the safety of them is the best among all types of vaccines.
In fact, all of the COVID-19 vaccines do not increase the risk of serious adverse events. Therefore, there is no firm rule that a certain type of vaccine must be used. Each type of vaccine could be used according to the actual situation of each country and the characteristics of different types of vaccines.

Original title:
Efficacy and Safety of COVID-19 Vaccines in Phase III Trials: A Meta-Analysis by Cheng H, Peng Z, Yunxian Yu HL.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8228087/

Additional information of El Mondo:
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