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Review
. 2023 Jan;33(1):e2398.
doi: 10.1002/rmv.2398. Epub 2022 Sep 23.

SARS-CoV-2 Omicron and its current known unknowns: A narrative review

Trang Thi Bich Le  1   2 , Tamilarasy Vasanthakumaran  1   3 , Hau Nguyen Thi Hien  1   4   5 , I-Chun Hung  1 , Mai Ngoc Luu  1   6 , Zeeshan Ali Khan  1   7 , Nguyen Thanh An  1   4   5 , Van Phu Tran  1   8 , Wei Jun Lee  1   9 , Jeza Muhamad Abdul Aziz  1   10   11 , Tasnim Ali  1   12 , Shyam Prakash Dumre  13 , Nguyen Tien Huy  1   14
Affiliations
Review

SARS-CoV-2 Omicron and its current known unknowns: A narrative review

Trang Thi Bich Le et al. Rev Med Virol. 2023 Jan.

Abstract

The emergence of the SARS-CoV-2 Omicron variant (B.1.1.529) has created great global distress. This variant of concern shows multiple sublineages, importantly B.1.1.529.1 (BA.1), BA.1 + R346K (BA.1.1), and B.1.1.529.2 (BA.2), each with unique properties. However, little is known about this new variant, specifically its sub-variants. A narrative review was conducted to summarise the latest findings on transmissibility, clinical manifestations, diagnosis, and efficacy of current vaccines and treatments. Omicron has shown two times higher transmission rates than Delta and above ten times more infectious than other variants over a similar period. With more than 30 mutations in the spike protein's receptor-binding domain, there is reduced detection by conventional RT-PCR and rapid antigen tests. Moreover, the two-dose vaccine effectiveness against Delta and Omicron variants was found to be approximately 21%, suggesting an urgent need for a booster dose to prevent the possibility of breakthrough infections. However, the current vaccines remain highly efficacious against severe disease, hospitalisation, and mortality. Japanese preliminary lab data elucidated that the Omicron sublineage BA.2 shows a higher illness severity than BA.1. To date, the clinical management of Omicron remains unchanged, except for monoclonal antibodies. Thus far, only Bebtelovimab could sufficiently treat all three sub-variants of Omicron. Further studies are warranted to understand the complexity of Omicron and its sub-variants. Such research is necessary to improve the management and prevention of Omicron infection.

Keywords: B.1.1.529; BA.1; BA.2; Omicron; SARS-CoV-2; subvariant.

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Conflict of interest statement

The authors declare they have no conflict of interest.

Figures

FIGURE 1
FIGURE 1
The geographical representation of the omicron case distribution as of 8 January 2022
FIGURE 2
FIGURE 2
The mutations of the omicron variant highlighting the differences among omicron subgroups and shared mutations with ancestral variants
FIGURE 3
FIGURE 3
The geographical representation of the omicron sublineage dominance with percentage of mutation dominance across the globe
FIGURE 4
FIGURE 4
A bar graph depicting the number of confirmed omicron cases with a trend line showing the number of deaths due to omicron
FIGURE 5
FIGURE 5
A graph comparing the percentage prevalence of symptoms between the omicron and delta variant
FIGURE 6
FIGURE 6
A line graph demonstrating the dominance of omicron across the countries with the most cases as of 10 January 2021
See this image and copyright information in PMC

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