Meta-Analysis
Copyright ©The Author(s) 2022. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Meta-Anal. Jun 28, 2022; 10(3): 177-185
Published online Jun 28, 2022. doi: 10.13105/wjma.v10.i3.177
Clinical outcomes of the omicron variant compared with previous SARS-CoV-2 variants; meta-analysis of current reports
Mohsen Karbalaei, Masoud Keikha
Mohsen Karbalaei, Department of Microbiology and Virology, School of Medicine, Jiroft University of Medical Sciences, Jiroft, Iran
Masoud Keikha, Department of Microbiology and Virology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
Author contributions: Keikha M contribute in design of study, study conceptual, literature search, writhing the draft; Karbalaei M revision the draft and manuscript editing; all authors agree with publish in this journal.
Conflict-of-interest statement: All the authors declare that they have no conflict of interest.
PRISMA 2009 Checklist statement: This study was conducted according to PRISMA 2009 Checklist statement.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Masoud Keikha, PhD, Doctor, Instructor, Teaching Assistant, Department of Microbiology and Virology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran. masoud.keykha90@gmail.com
Received: March 24, 2022
Peer-review started: March 24, 2022
First decision: April 28, 2022
Revised: May 15, 2022
Accepted: June 24, 2022
Article in press: June 24, 2022
Published online: June 28, 2022
ARTICLE HIGHLIGHTS
Research background

Omicron (B.1.1.529) is a new variant of concern of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2); however, there is no comprehensive analysis regarding clinical features, disease severity, and clinical outcomes of infection with this variant.

Research motivation

There is insufficient evidence regarding clinical characteristics, standard therapeutic regimen, and efficacy of currently available vaccines against the omicron variant.

Research objectives

This study was a comprehensive review and statistical analysis to compare the clinical characteristics of infection with the omicron and previous variants.

Research methods

We searched major international databases consisting ISI Web of Science, PubMed, Scopus, and MedRxiv to collect the potential relevant documents. Finally, clinical features, e.g., death rate, intensive care unit (ICU) admission, length of hospitalization, and need for mechanical ventilation of patients infected with omicron variant compared with previous variants, were assessed.

Research results

Twelve articles met our criteria. These studies investigated the clinical outcomes of infection with SARS-CoV-2 omicron variant compared with other variants such as alpha, beta and delta. Our results suggested that ICU admission, need for mechanical ventilation, and death rate were significantly lower for omicron than previous variants. In addition, the average length of hospitalization during the omicron wave was significantly shorter than for other variants.

Research conclusions

The infectivity of the omicron variant was much higher than for previous variants due to the presence of several mutations, particularly in the spike protein. However, disease severity was mild to moderate disease compared with previous variants.

Research perspectives

We revealed that the disease severity of infection with omicron was lower than for previous variants. However, this variant was more contagious. Nevertheless, further investigation with larger samples is needed to confirm the present findings.