Abstract

Omicron SARS-CoV-2 variant: a new chapter in the COVID-19 pandemic

On Nov 25, 2021, about 23 months since the first reported case of COVID-19 and after a global estimated 260 million cases and 5•2 million deaths, a new SARS-CoV-2 variant of concern (VoC), omicron, was reported. Although previous VoCs emerged in a world in which natural immunity from COVID-19 infections was common, this fifth VoC has emerged at a time when vaccine immunity is increasing in the world.

The emergence of the alpha, beta, and delta SARS-CoV-2 VoCs were associated with new waves of infections, sometimes across the entire world. For example, the increased transmissibility of the delta VoC was associated with, among others, a higher viral load, longer duration of infectiousness, and high rates of reinfection, because of its ability to escape from natural immunity, which resulted in the delta VoC rapidly becoming the globally dominant variant. The delta VoC continues to drive new waves of infection and remains the dominant VoC during the fourth wave in many countries. Concerns about lower vaccine efficacy because of new variants have changed our understanding of the COVID-19 endgame, disabusing the world of the notion that global vaccination is by itself adequate for controlling SARS-CoV-2 infection. Indeed, VoCs have highlighted the importance of vaccination in combination with existing public health prevention measures, such as masks, as a pathway to viral endemicity.


Author(s): Ayush Pandey

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