ABSTRACT
The world has been combating different variants of SARS-COV-19 since its first outbreak in Wuhan city. SARS-COV-19 is caused by the coronavirus. The corona virus mutates and becomes more transmissible than earlier variants as the day passes. Till 24 November 2021, SARS-COV-19 has four variants Alpha, Beta, Gamma, and Delta, respectively. Among them, the delta variant caused severe havoc across the world. South Africa registered a new variant with the World Health Organization (WHO) on 24 November 2021, which is much more transmissible than previous variants. The WHO classified it as a variant of concern (VOC) on 26 November 2021 and called it the Greek letter Omicron (B.1.1.529), the fifteenth letter in the alphabet. Here a serious attempt was made to comprehend the omicron variant's origin, nomenclature, characteristics, mutations, the difference between delta and omicron variant, epidemiology, transmission, clinical features, impact on immunity, immune evasion, vaccines efficacy, etc.