EG.5.1 Covid variant takes off, India not at risk currently

EG.5.1 Covid variant takes off, India not at risk currently

Subject :Science and technology

Section: Health

Context:

• EG.5, a descendent of the Omicron lineage of XBB.1.9.2, was designated a variant of interest (VOI) after risk evaluation by the World Health Organization on August 10, 2023. It was previously designated a variant under monitoring.

Details:

• EG.5 may spread globally and contribute to a surge in case incidence.
• EG.5 was first reported on February 17 of this year. As of August 9, EG.5 has been reported from a total of 48 countries.
• In India, one EG.5.1 was detected in Maharashtra.
• The global genome sequencing databases indicate the remarkable rise of the new sublineage. EG.5.1 is taking off everywhere. It is definitely out-competing its predecessors in the XBB lineage that were dominating most of 2023.
• The recent VOI classification of EG.5 suggests that due to changes in the receptor binding domain of the spike protein, the variant escapes neutralization by antibodies generated from previous infections or vaccinations.
• EG.5 carries an additional F456L amino acid mutation in the spike protein compared to the parent XBB.1.9.2 subvariant and XBB.1.5.
• Within the EG.5 lineage, the subvariant EG.5.1 has an additional spike mutation Q52H and represents 88 per cent of the available sequences for EG.5 and its descendent lineages.

Virus variant:

• Variants of a virus have one or more mutations that differentiate it from the other variants that are in circulation. While most mutations are deleterious for the virus, some make it easier for the virus to survive.

Classification:

The US Centers for Disease Control and Prevention (CDC) classifies variants into four categories:

1. Variant of Interest (VOI):
   • A variant with specific genetic markers that have been associated with changes to receptor binding, reduced neutralization by antibodies generated against previous infection or vaccination, reduced efficacy of treatments, potential diagnostic impact, or predicted increase in transmissibility or disease severity.
   • An example of VOI is the 1.617 variant of the virus which has two mutations, referred to as E484Q and L452R.
   • This variant is classified as a VOI by the World Health Organization (WHO) as well.
   • Both are separately found in many other coronavirus variants, but they have been reported together for the first time in India.
2. Variant of Concern (VOC):
   • A variant for which there is evidence of an increase in transmissibility, more severe disease (e.g., increased hospitalizations or deaths), significant reduction in neutralization by antibodies generated during previous infection or vaccination, reduced effectiveness of treatments or vaccines, or diagnostic detection failures.
   • The 1.1.7 (UK variant), B.1.351 (South Africa Variant), P.1 (Brazil Variant), B.1.427, and B.1.429 variants circulating in the US are classified as VOCs.
3. Variant of High Consequence:
   • A variant of high consequence has clear evidence that prevention measures or medical countermeasures have significantly reduced effectiveness relative to previously circulating variants.
   • So far, the CDC has not found variants of high consequence in circulation in the US.
4. Variants Under Investigation (VUI):
   • Public Health England (PHE) says that if the variants of SARS-CoV-2 are considered to have epidemiological, immunological or pathogenic properties, they are raised for formal investigation.
   • At this point, the variants emerging from the 1.617 lineage are designated as VUI.