Recent insights into SARS-CoV-2 omicron variant

Abstract

The SARS-CoV-2 omicron variant (B.1.1.529) was first identified in Botswana and South Africa, and its emergence has been associated with a steep increase in the number of SARS-CoV-2 infections. The omicron variant has subsequently spread very rapidly across the world, resulting in the World Health Organization classification as a variant of concern on 26 November 2021. Since its emergence, great efforts have been made by research groups around the world that have rapidly responded to fill our gaps in knowledge for this novel variant. A growing body of data has demonstrated that the omicron variant shows high transmissibility, robust binding to human angiotensin-converting enzyme 2 receptor, attenuated viral replication, and causes less severe disease in COVID-19 patients. Further, the variant has high environmental stability, high resistance against most therapeutic antibodies, and partial escape neutralisation by antibodies from convalescent patients or vaccinated individuals. With the pandemic ongoing, there is a need for the distillation of literature from primary research into an accessible format for the community. In this review, we summarise the key discoveries related to the SARS-CoV-2 omicron variant, highlighting the gaps in knowledge that guide the field's ongoing and future work.

Keywords: COVID-19; SARS-CoV-2; coronavirus; omicron; pandemic; variants of concern.

FIGURE 1

SARS‐CoV‐2 omicron variant and several characteristics related to this novel variant. (a) SARS‐CoV‐2 virion and spike protein; (b) the mutations of omicron variant found in the spike protein; (c) the main findings and recent advances related to the omicron variant. The figure was created using Biorender.com

FIGURE 2

A schematic illustration of two cell entry pathways that are known to be used by SARS‐CoV‐2. Recent insights demonstrated that the SARS‐CoV‐2 omicron variant spike enters cells less efficiently by TMPRSS2‐dependent plasma membrane fusion (right) and demonstrates a greater dependency on cell entry via the endocytic pathway (left)., ACE2: angiotensin‐converting enzyme 2; TMPRSS2: transmembrane serine protease 2. The figure was created using Biorender.com

FIGURE 3

SARS‐CoV‐2 infection in the respiratory tract and immune response induced by different vaccine platforms against omicron variant. Analysing specimens obtained from individuals ∼6 months post‐vaccination, it was found that T cell responses are preserved, while significant decreases are observed for memory B cell response. Data used is this figure was obtained from Tarke et al. ACE2: angiotensin‐converting enzyme 2. The figure was created using Biorender.com