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The genomic and clinical features of the COVID-19 Omicron variant: a narrative review

Coronavirus disease 2019 (COVID-19) has been a major cause of morbidity and mortality worldwide since December 2019. Up to July 2022, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected more than 570 million people and contributed to the death of more than 6.4 million individuals around the world. Intriguingly, after more than 2 years of its existence, the infection rate remains high, and the pandemic has not been resolved. Following the devastating impacts of the B.1.617.2 (Delta) variant, predominantly in health and socioeconomic sectors, there was a high expectation that the viral disease could be tamed by the rapid, collaborative and evolutionary development of COVID-19 vaccines. Indeed, the massive vaccination program in several countries has successfully reduced the fatality of the disease and together with the implementation of strict public health and social control measures (PHSCM), the infection rate could also be lowered.1–4 For example, in the United States (US), COVID-19 vaccines reduced the overall attack rate (i.e., number of new cases during specified time interval divided by the total population at start of time interval) in vaccinated individuals by 4.4% on day 300 from the start of vaccination (9% in the unvaccinated group vs. 4.6% in the vaccinated group), as well as the rate of hospitalization, intensive care unit (ICU) occupancy, incidence of major adverse events and mortality.1 Despite the reported effectivity decline of BNT162b2 and ChAdOx1 vaccines against the Delta variant (10–13% and 16% lower than B.1.1.7 (Alpha) variant, respectively),5 vaccination was proven to remain effective in reducing infection and accelerating viral clearance,2 as well as lowering mortality caused by the Delta variant.4

However, a glimpse of hope to end the pandemic was once again challenged by the presence of the new COVID-19 B.1.1.529 (a.k.a. Omicron) variant. Since its first reported appearance in South Africa in November 2021, it has rapidly taken the attention of experts around the world. A few days after its appearance, the World Health Organization (WHO) immediately classified Omicron as a Variant of Concern (VoC). Since then, it has vastly spread from Africa to Europe, then Asia, Australia and America (Figure 1). Since early January 2022, the Omicron variant has become the major COVID-19 variant in most countries (Table 1)6,7 and contributed to the rise of COVID-19 incidence from ~600,000 new cases in late November 2021 to ~3.5 million cases in late January 2022.

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Authors: Decsa Medika Hertanto , Henry Sutanto , Maria Inge Lusida, Kuntaman Kuntaman, Djoko Santoso

Corresponding author: Djoko Santoso
Competing interests: No competing interests were disclosed.
Grant information: The author(s) declared that no grants were involved in supporting this work.
Copyright: © 2022 Hertanto DM et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.