Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2023 Jan;33(1):e2391.
doi: 10.1002/rmv.2391. Epub 2022 Aug 26.

Update on the omicron sub-variants BA.4 and BA.5

Trina Ekawati Tallei  1 , Saad Alhumaid  2 , Zainab AlMusa  3 , Fatimawali  4 , Diah Kusumawaty  5 , Ahlam Alynbiawi  6 , Abeer N Alshukairi  7   8 , Ali A Rabaan  8   9   10
Affiliations
Review

Update on the omicron sub-variants BA.4 and BA.5

Trina Ekawati Tallei et al. Rev Med Virol. 2023 Jan.

Abstract

Several nations have recently begun to relax their public health protocols, particularly regarding the use of face masks when engaging in outdoor activities. This is because there has been a general trend towards fewer cases of coronavirus disease 2019 (COVID-19). However, new Omicron sub-variants (designated BA.4 and BA.5) have recently emerged. These two subvariants are thought to be the cause of an increase in COVID-19 cases in South Africa, the United States, and Europe. They have also begun to spread throughout Asia. They evolved from the Omicron lineage with characteristics that make them even more contagious and which allow them to circumvent immunity from a previous infection or vaccination. This article reviews a number of scientific considerations about these new variants, including their apparently reduced clinical severity.

Keywords: BA.4 and BA.5; COVID-19; SARS-CoV-2; evolution; omicron sub-variants.

PubMed Disclaimer

Conflict of interest statement

The author declares that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.

Figures

FIGURE 1
FIGURE 1
Three new clades of SARS‐CoV‐2 Omicron evolution. 22A corresponds to Pango lineage BA.4, 22B corresponds to Pango lineage BA.5, and 22C corresponds to Pango lineage BA.2.12.1. (Adapted from Nextstrain; https://nextstrain.org/ncov/gisaid/global/6m)
FIGURE 2
FIGURE 2
Phylogenies based on mutations at spike protein (a) (available at https://nextstrain.org/ncov/gisaid/global/6m?c=S1_mutations) and clade (b) (available at https://nextstrain.org/ncov/gisaid/global/6m) show evolutionary relationships of SARS‐CoV‐2 from the ongoing COVID‐19 pandemic. The phylogenies are relatively rooted in early Wuhan samples. Temporal resolution assumes that there is a nucleotide substitution rate of 8 × 10−4 substitutions per site per year. The results of Obermeyer are used as the basis for the calculation of mutational fitness
FIGURE 3
FIGURE 3
New waves of COVID‐19 appear periodically and are triggered by the emergence of new variants (adapted from World Health Organization (WHO) COVID‐19 Dashboard; https://covid19.who.int)
See this image and copyright information in PMC

References

    1. Celik I, Abdellattif MH, Tallei TE. An Insight based on computational analysis of the interaction between the receptor‐binding domain of the Omicron variants and human angiotensin‐converting enzyme 2. Biology. 2022;11(5):797. 10.3390/biology11050797 - DOI - PMC - PubMed
    1. Khandia R, Singhal S, Alqahtani T, et al. Emergence of SARS‐CoV‐2 Omicron (B.1.1.529) variant, salient features, high global health concerns and strategies to counter it amid ongoing COVID‐19 pandemic. Environ Res. 2022;209:112816. 10.1016/j.envres.2022.112816 - DOI - PMC - PubMed
    1. Martin DP, Lytras S, Lucaci AG, et al. Selection analysis identifies unusual clustered mutational changes in Omicron lineage BA.1 that likely impact Spike function. bioRxiv Prepr Serv Biol. Published online January. 2022. 10.1101/2022.01.14.476382 - DOI - PMC - PubMed
    1. Fan Y, Li X, Zhang L, Wan S, Zhang L, Zhou F. SARS‐CoV‐2 Omicron variant: recent progress and future perspectives. Signal Transduct Targeted Ther. 2022;7(1):141. 10.1038/s41392-022-00997-x - DOI - PMC - PubMed
    1. Abas AH, Marfuah S, Idroes R, et al. Can the SARS‐CoV‐2 Omicron variant confer natural immunity against COVID‐19? Molecules. 2022;27(7):2221. 10.3390/molecules27072221 - DOI - PMC - PubMed