Outcomes of omicron sub-lineages BA.1.1 and BA.2 infection compared with the sub-lineage BA.1 infection in emergency departments' patients.

The omicron SARS-CoV-2 variant of concern (B.1.1.529) was first reported in South Africa in November, 2021. Several reports indicated that the infection with omicron (BA.1 sub-lineage) was associated with a lower risk of hospitalization and severe outcomes compared with delta (B.1.617.2) variant infection1,2. During the 2022 year, the Omicron variant was still the dominant circulating variant, and has divided into several sub-lineages – BA.1.1 and BA.2, then later BA.3, BA.4 and BA.5.3 Data on the clinical patterns and outcomes of Omicron sub-lineages infections are still scarce.