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
Processing time: 102 Days and 20.4 Hours
Abstract
BACKGROUND

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

AIM

To compare the clinical characteristics of infection with omicron and previous variants of SARS-CoV-2.

METHODS

We searched major international databases consisting ISI Web of Science, PubMed, Scopus, MedRxiv, and Reference Citation Analysis to collect the potential relevant documents. Finally, clinical features, e.g., death rate, intensive care unit (ICU) admission, length of hospitalization, and mechanical ventilation, of infection with SARS-CoV-2 omicron variant compared with previous variants were assessed using odds ratio and 95% confidence intervals by Comprehensive Meta-Analysis software version 2.2.

RESULTS

A total of 12 articles met our criteria. These investigated the clinical outcomes of infection with 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.

CONCLUSION

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

Keywords: SARS-CoV-2; COVID-19; Omicron; Infectious disease

Core Tip: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) omicron (B.1.1.529) is a variant of concern that was first identified on 24 November 2021 as a new global threat. However, due to the lack of comprehensive statistical analysis, clinical characteristics and disease outcomes of infection with omicron variant have remained unknown. Hence, the comparison of clinical profile between cases infected with this new variant and previous variants will lead to the establishment of a strategy regarding appropriate management and global control of this variant.