WHO Statement on Omicron sublineage BA.2

As part of its ongoing work to track variants, WHO's Technical Advisory Group on SARS-CoV-2 Virus Evolution ( Label-VE) met history to bandy the rearmost substantiation on the Omicron variant of concern, including its sublineages BA.1 and BA.2.

Grounded on available data on transmission, inflexibility, reinfection, diagnostics, rectifiers and impacts of vaccines, the group corroborated that the BA.2 sublineage should continue to be considered a variant of concern and that it should remain classified as Omicron. The group emphasized that BA.2 should continue to be covered as a distinct sublineage of Omicron by public health authorities.

The Omicron variant of concern is presently the dominant variant circulating encyclopedically, counting for nearly all sequences reported to GISAID. Omicron is made up of several sublineages, each of them being covered by WHO and mates. Of them, the most common bones are BA.1, BA.1.1 (or Nextstrain clade 21K) and BA.2 (or Nextstrain clade 21L). At a global position, the proportion of reported sequences designated BA.2 has been adding relative to BA.1 in recent weeks, still the global rotation of all variants is reportedly declining.

BA.2 differs from BA.1 in its inheritable sequence, including some amino acid differences in the shaft protein and other proteins. Studies have shown that BA.2 has a growth advantage over BA.1. Studies are ongoing to understand the reasons for this growth advantage, but original data suggest that BA.2 appears innately more transmittable than BA.1, which presently remains the most common Omicron sublineage reported. This difference in transmissibility appears to be much lower than, for illustration, the difference between BA.1 and Delta. Further, although BA.2 sequences are adding in proportion relative to other Omicron sublineages (BA.1 and BA.1.1), there's still a reported decline in overall cases encyclopedically.

Studies are assessing the threat of reinfection with BA.2 compared to BA.1. Reinfection with BA.2 following infection with BA.1 has been proved, still, original data from population-position reinfection studies suggest that infection with BA.1 provides strong protection against reinfection with BA.2, at least for the limited period for which data are available.

While reaching the below determination, the Label-VE also looked at primary laboratory data from Japan generated using beast models without any impunity to SARS-CoV-2 which stressed that BA.2 may beget more severe complaints in hamsters compared to BA.1. They also considered real-world data on clinical inflexibility from South Africa, the United Kingdom, and Denmark, where impunity from vaccination or natural infection is high in this data, there was no reported difference in inflexibility between BA.2 and BA.1.

WHO will continue to nearly cover the BA.2 lineage as part of Omicron and requests countries to continue to be watchful, to cover and report sequences, as well as to conduct independent and relative analyses of the different Omicron sublineages.

The Label-VE meets regularly and continues to bandy available data on transmissibility and inflexibility of variants, and their impact on diagnostics, rectifiers, and vaccines

Background

The uninterrupted rotation of SARS-CoV-2 and the emergence of variants requires constant alert and a global medium to track, cover and estimate the evolving situation. In June 2020, WHO established an informal Virus Evolution Expert Working Group (VEWG) to specifically assess SARS-CoV-2 elaboration, mutations and variants. This independent group of experts has been homogenized under the name Technical Advisory Group on SARS-CoV-2 Virus Evolution ( Label-VE) and continues to meet regularly to bandy and assay the impact of SARS-CoV-2 variants on transmissibility, clinical donation, complaint inflexibility, diagnostics and rectifiers and determine whether a given variant constitutes a variant of interest (VOI) or a variant of concern (VOC) according to WHO delineations.

The recommendations of Label-VE are used to inform WHO on global, indigenous and public COVID-19 forestallment and control strategies and employed by other WHO premonitory groups, similar to the Expert Advisory Group on COVID-19 Vaccine Composition ( Label-CO-VAC), the Strategic Advisory Group of Experts on Immunization ( Savant) and the Strategic and Technical Advisory Group for Infectious Hazards (STAG-IH).