[Progress in research of etiology and epidemiology of 2019-nCoV Omicron variant]

2019-nCoV Omicron variant has become predominant in the world. New subvariants with further mutations in their spike proteins are continuously emerging. Compared with the wild type and other variants of concern, Omicron variant exhibits altered etiological and epidemiological characteristics, with weakened pathogenicity and toxicity in laboratory mice and hamsters as well as enhanced immune escape capacity. The human infections are more likely to be asymptomatic and mild characterized by upper respiratory tract symptoms with reduced risk of hospitalization and death. In addition, Omicron variant can transmit more rapidly and shows shorter incubation period to cause infection, and the variant is more likely to transmit through contamination of object surfaces and aerosols spread. This paper summarizes the etiological and epidemiological characteristics of Omicron variant to provide a reference for the effective prevention and control of Omicron variant infection.