COVID-19 Vaccines: A Review of the Safety and Efficacy of Current Clinical Trials

Abstract

Various strategies have been designed to contain the COVID-19 pandemic. Among them, vaccine development is high on the agenda in spite of the unknown duration of the protection time. Various vaccines have been under clinical trials with promising results in different countries. The protective efficacy and the short-term and long-term side effects of the vaccines are of major concern. Therefore, comparing the protective efficacy and risks of vaccination is essential for the global control of COVID-19 through herd immunity. This study reviews the most recent data of 12 vaccines to evaluate their efficacy, safety profile and usage in various populations.

Keywords: COVID-19; efficacy; herd immunity; safety; vaccine.

Figure 1

Schematic graph of the comparison between DNA and mRNA vaccine in terms of mechanisms. DNA vaccine is a circle DNA which contains the spike gene of SARS-CoV-2. After electroporation, cell membrane permeation will be increased, allowing DNA enter into cytoplasm thereby reaching to the nuclear. Subsequently, DNA will be translated into mRNA, which will be further translated into SARS-CoV-2 spike proteins and express on cell membrane. Nanoparticle-encapsulated mRNA encoding SARS-CoV-2 antigen will be integrated into cytoplasm. The spike mRNA utilizes ribosome and bases to translate spike proteins, which express on the cell membrane. The membrane spike protein will be recognized by antigen presenting cell (APC) thereby activating immune reaction.