Abstract: Coronavirus disease 2019 (COVID-19) pandemic is still a great threat to global public health, with a daily increase of 1 738 701 cases and 5150 deaths in 11 January, 2022. Recently, multiple variants of 2019-nCoV have emerged around the world, especially the newly 2019-nCoV variant B.1.1.529 (Omicron), a variant of concern (VOC), which are harboring up large number of mutations in its spike protein, the target of multi-faceted immune response generated by both prior infection or vaccination, leading to the immune evasion of neutralization. Optimistically, Omicron infection produces milder disease than previous strains, such as increased proportion of asymptomatic or mild cases and fewer hospital admissions. However, global health systems could still come under huge pressure considering the super spread rate of Omicron variant, which has outcompeted Delta and other variants within weeks in some countries and regions. Therefore, here we reviewed the molecular mechanism underlying the immune evasion, milder pathogenicity and enhanced transmissibility of Omicron, and further provided scientific suggestions to prevent and control the Omicron variant.

Key words: 2019 novel coronavirus, Coronavirus disease 2019, Omicron, Variant of concern, Spike protein