SARS-CoV-2 Omicron variant

Omicron (B.1.1.529) is a heavily mutated 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 B.1.1.529 variant, several subvariants of Omicron have emerged, including: BA.1, BA.2, BA.3, BA.4, and BA.5. Two subvariants of BA.5 emerged by October 2022, called BQ.1 and BQ.1.1.

In mid-2023, the extremely-mutated BA.2.86 variant emerged. Its main descendent, JN.1 (BA.2.86.1.1), emerged soon afterward and swept the globe that winter, becoming dominant within a few months. Since then, all circulating lineages have descended from JN.1. JN.1 went on to spawn multiple notable sublineages, including KP.3.1.1 and XEC in 2024, and LP.8.1, NB.1.8.1, and XFG in 2025. XFG became the dominant variant globally over the summer of 2025.

Three doses of a COVID-19 vaccine provide protection against severe disease and hospitalization caused by Omicron and its subvariants. For three-dose vaccinated individuals, the BA.4 and BA.5 variants are more infectious than previous subvariants but there is no evidence of greater sickness or severity.