Classification of Omicron (B.1.1.529): SARS-CoV-2 Variant of Concern (VOC)

The Technical Advisory Group on SARS-CoV-2 Virus Evolution (TAG-VE), an independent group of experts that periodically monitors and evaluates the evolution of SARS-CoV-2 and assesses if specific mutations and combinations of mutations alter the behavior of the virus, was convened on November 26 to assess the SARS-CoV-2 variant: B.1.1.529.

The B.1.1.529 variant was first reported to World Health Organization from South Africa on November 24. The epidemiological situation in South Africa has been characterized by three distinct peaks in reported cases, the latest of which was predominantly the Delta variant. In recent weeks, infections have increased steeply, coinciding with the detection of B.1.1.529 variant. The first known confirmed B.1.1.529 infection was from a specimen collected on November 9, 2021.

According to the TAG-VE, this variant has a large number of mutations, some of which are concerning. Preliminary evidence suggests an increased risk of reinfection with this variant, as compared to other VOCs. The number of cases of this variant appears to be increasing in almost all provinces in South Africa. Current SARS-CoV-2 PCR diagnostics continue to detect this variant. Several labs have indicated that for one widely used PCR test, one of the three target genes is not detected (called S gene dropout or S gene target failure) and this test can therefore be used as marker for this variant, pending sequencing confirmation.