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 96 4–0 92 7) 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
Efficacy and Safety of COVID-19 Vaccines: A Systematic Review and Meta-Analysis of Randomized Clinical Trials