Global emerging Omicron variant of SARS-CoV-2: Impacts, challenges and strategies

Abstract

Newly emerging variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are continuously posing high global public health concerns and panic resulting in waves of coronavirus disease 2019 (COVID-19) pandemic. Depending on the extent of genomic variations, mutations and adaptation, few of the variants gain the ability to spread quickly across many countries, acquire higher virulency and ability to cause severe disease, morbidity and mortality. These variants have been implicated in lessening the efficacy of the current COVID-19 vaccines and immunotherapies resulting in break-through viral infections in vaccinated individuals and recovered patients. Altogether, these could hinder the protective herd immunity to be achieved through the ongoing progressive COVID-19 vaccination. Currently, the only variant of interest of SARS-CoV-2 is Omicron that was first identified in South Africa. In this review, we present the overview on the emerging SARS-CoV-2 variants with a special focus on the Omicron variant, its lineages and hybrid variants. We discuss the hypotheses of the origin, genetic change and underlying molecular mechanism behind higher transmissibility and immune escape of Omicron variant. Major concerns related to Omicron including the efficacy of the current available immunotherapeutics and vaccines, transmissibility, disease severity, and mortality are discussed. In the last part, challenges and strategies to counter Omicron variant, its lineages and hybrid variants amid the ongoing COVID-19 pandemic are presented.

Keywords: COVID-19; Emerging variance; Omicron; SARS-CoV-2; Variant of concern.

Fig. 1

Mutations of spike protein amino acids of Omicron variant of SARS-CoV-2 causing in higher infectivity (by strengthening the binding with host ACE2 receptors) and reduced neutralization by antibodies (mAb, T-cell, or convalescent plasma). These changes of biological characteristics encourage higher transmissibility of the virus infecting both people with and without antibodies.

Fig. 2

Newly emerging Omicron and its lineages with increased infectivity infect both adults and kids and mainly target respiratory lung system, intestines and brain. Major Omicron lineages that spreading include BA.1, BA.2, BA4/5, with minor difference in RBD mutations in their spike. Omicron also alters and increases its binding affinity to human ACE2 to allow more efficient entry into host cells, leading higher infectivity and transmissibility.

Fig. 3

Strategies to tackle SARS-CoV-2 emerging variants.