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. 2023 Dec 31;19(1):2212568.
doi: 10.1080/21645515.2023.2212568.

The relative prevalence of the Omicron variant within SARS-CoV-2 infected cohorts in different countries: A systematic review

Aparajita Sarkar, Sara Omar  1 , Aya Alshareef  1 , Kareem Fanous  1 , Shaunak Sarker  1 , Hasan Alroobi  1 , Fahad Zamir  2 , Mahmoud Yousef  2 , Dalia Zakaria  2
Affiliations

The relative prevalence of the Omicron variant within SARS-CoV-2 infected cohorts in different countries: A systematic review

Aparajita Sarkar et al. Hum Vaccin Immunother. .

Abstract

The Omicron variant of SARS-CoV-2 was detected in October 2021 and exhibited high transmissibility, immune evasion, and reduced severity when compared to the earlier variants. The lesser vaccine effectiveness against Omicron and its reduced severity created vaccination hesitancy among the public. This review compiled data reporting the relative prevalence of Omicron as compared to the early variants to give an insight into the existing variants, which may shape the decisions regarding the targets of the newly developed vaccines. Complied data revealed more than 90% prevalence within the infected cohorts in some countries. The BA.1 subvariant predominated over the BA.2 during the early stages of the Omicron wave. Moreover, BA.4/BA.5 subvariants were detected in South Africa, USA and Italy between October 2021 and April 2022. It is therefore important to develop vaccines that protect against Omicron as well as the early variants, which are known to cause more severe complications.

Keywords: Alpha; BA.1; BA.2; BA.4; BA.5; Beta; COVID-19; Delta; Omicron; SARS-CoV-2; predominance; prevalence.

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Conflict of interest statement

No potential conflict of interest was reported by the author(s).

Figures

Figure 1.
Figure 1.
Screening and study selection protocol.
Figure 2.
Figure 2.
The most recently reported prevalence of the Omicron variant infections in cohorts in different countries as reported by the included studies. The prevalence is reported as a percentage of the individuals infected with Omicron in a cohort infected with SARS-CoV-2. The dates are specified for each country.
Figure 3.
Figure 3.
Prevalence of the Omicron variant in different countries during the periods, June 2021 – January 2022 and December 2021 – June 2022. Results were complied from multiple cohorts infected with SARS-CoV-2 in each country (if available). (a) North and Latin America, (b) Africa and Australia, (c) Europe, (d) Asia.
Figure 4.
Figure 4.
Prevalence of the subvariants of Omicron in different countries during different time periods. Results were either compiled from multiple cohorts infected with SARS-CoV-2 (if available) or reported from single studies in each country. (a) North and Latin America, (b) Africa and Australia, (c) Europe, (d) Asia.
See this image and copyright information in PMC

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