Abstract
On 26 November 2021, the World Health Organization (WHO) identified the B.1.1.529 variant, or Omicron variant, as the fifth variant of concern (VOC) of SARS-CoV-2. The B.1.1.529 Omicron variant of SARS-CoV-2 includes five lineages, BA.1, BA.2, BA.3, BA.4. and BA.5. During the past six months, several identified sublineages of B.1.1.529 have rapidly spread globally. Although the lineages BA.1 and BA.2 initially predominated, BA.4, BA.5, and sublineage BA.2.12.1 are now dominant in Europe and the USA. On 12 May 2022, the European Centre for Disease Prevention and Control (ECDC) reclassified BA.4 and BA.5 from variants of interest (VOI) to variants of concern (VOC). BA.2.12.1, BA.4, and BA.5 have shown higher transmissibility and increased neutralization evasion compared with BA.2 when tested against plasma from patients with triple-vaccination and following infection with BA.1. On 7 June 2022, the World Health Organization (WHO) added a new category to its SARS-CoV-2 variant tracking system, the VOC Lineages Under Monitoring (VOC-LUM), which aims to inform global public health authorities of the VOC lineages and sublineages that may require prioritized attention and monitoring. This Editorial aims to present an update on the lineages and sublineages of the Omicron variant of SARS-CoV-2 and the VOC-LUM initiative from the WHO.