Omicron: Flighty factor challenging global vaccine campaigns or the ending signal of the COVID-19 pandemic

Coronavirus disease 2019 (COVID-19) has been a great global public health issue for two years. In November 2021, a new variant, B.1.1.529, of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was identified in South Africa and caused a rapid rise in COVID-19 cases. On 26 November 2021, the World Health Organization (WHO) named this variant Omicron and classified it as a variant of concern (VoC). The spike protein of this variant contains a high number of mutations, raising concerns about viral transmissibility, pathogenicity, immune evasion, and neutralization by antibodies. When the early Omicron surge occurred, preliminary data showed that the transmission of this variant was extremely fast, but the number of patients with severe symptoms was low. This review will describe the characteristics of the Omicron variant and compare the mutations of the spike in the five VoCs. We also look over research and opinions on the Omicron variant and evaluate epidemiological data from the Omicron wave and the Delta wave. In the review discussion, we will discuss Omicron whether it is a challenge for global vaccine campaigns, whether it is a sign of a waning pandemic, and how we acknowledge the new variant and future of the COVID-19 pandemic.