Omicron (B.1.1.529) is a variant of SARS-CoV-2 first reported to the World Health Organization (WHO) by the Network for Genomics Surveillance in South Africa on 24 November 2021. It was first detected in Botswana and has spread to become the predominant variant in circulation around the world. Following the original BA.1 variant, several subvariants of Omicron have emerged: BA.2, BA.3, BA.4, and BA.5. Since October 2022, two subvariants of BA.5 named BQ.1 and BQ.1.1 have spread rapidly.