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

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.

Mandate or Not Mandate: Knowledge, Attitudes, and Practices of Italian Occupational Physicians towards SARS-CoV-2 Immunization at the Beginning of Vaccination Campaign

“…It should be stressed that, even though available SARS-CoV-2/COVID-19 vaccines represent the “end-stage” of a pipeline that began several years ago [ 65 ], as they were developed and delivered in less than a year, in emergency settings, concerns about their actual safety and effectiveness have been repeatedly associated with moderate acceptance, hesitancy, or reluctance [ 66 , 67 ], including in HCWs [ 47 , 68 ]. Interestingly, while safety and effectiveness concerns have been somewhat dismissed by available reports [ 69 ], worries on the availability of vaccines were properly addressed, as the “kick-off” of the vaccination administration was actually hampered by a short supply of vaccines [ 70 ], even during the summer of 2021, difficulties in maintaining appropriate deliveries by manufacturers have often been reported.…”

Adverse Events Following Immunization Associated with the First and Second Doses of the ChAdOx1 nCoV-19 Vaccine among Healthcare Workers in Korea

“…Notably, Cheng et al's meta-analysis reported that all of the COVID-19 vaccines that have published their phase III clinical trials data did not increase the risk of serious adverse events [24]. Despite this, a number of important adverse events reported in real-world settings require careful evaluation and monitoring.…”

Association between Immunoglobulin G Levels and Adverse Effects Following Vaccination with the BNT162b2 Vaccine among Japanese Healthcare Workers

“…The rate of adverse effects of COVID-19 vaccines differs between countries because the type of vaccines used also differs by country [ 16 ]. Adverse effects range from mild to severe, including localized reactions, such as swelling and a rash at the injection site, and systemic reactions, including dyspnea and anaphylaxis [ 12 , 17 ]. Therefore, many people who do not have a general phobia toward vaccines tend to avoid vaccination because of a fear of adverse effects influenced by social media.…”