Vaccines Efficacy against Delta and Omicron Variants: A Comparative Study of Severe Acute Respiratory Syndrome CoronaVirus 2 (SARS-CoV-2) Vaccines

The SARS-CoV-2 pandemic has necessitated the rapid development and deployment of effective vaccines. This systematic review included articles published between 2019 and 2024 that focused on comparing the different vaccines against SARS-CoV-2 and its two variants: omicron and delta. Articles and scientific papers were selected based on originality, full- text availability, and English language. Excluded were case studies, reviews without data, or articles lacking full text or English translation. All relevant studies were systematically selected from Google Scholar, ResearchGate, Elsevier, Springer, and Academia.edu to identify relevant research exploring the six selected vaccines. The collected review utilized and identified a total of 33 studies. The researchers were able to use 17 of these studies for a more in-depth quantitative analysis. The qualitative analysis of all 16 studies revealed that pain and swelling in the injection area, headache, muscle pain, and fatigue are the most frequently observed side effects of vaccines on humans. This systematic review aims to comprehensively compare the efficacy of the vaccines and their side effects and their efficacy rate to omicron and delta variants. By conducting a rigorous analysis of existing literature, the researchers evaluate the efficacy of the vaccines and how they respond to omicron and delta variants when it comes to efficacy as well. The review will focus on key outcomes such as doses and frequencies, vaccine efficacy based on Phase III clinical trials, and side effects. Understanding the comparative strengths and limitations of different vaccines will inform public health and optimize vaccination strategies to mitigate the ongoing pandemic.