Recently, India’s Health Ministry said that a new double mutant variant of the coronavirus had been detected in addition to many other strains or Variants of Concern (VOCs) found in 18 states in the country.

Classification of Corona Variants

  • 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.
    • The SARS-CoV-2 (Corona) virus is evolving fast because of the scale at which it has infected people around the world. High levels of circulation mean it is easier for the virus to change as it is able to replicate faster.
    • The original pandemic virus (founder variant) was Wu.Hu.1 (Wuhan virus). In a few months, variant D614G emerged and became globally dominant.
  • Classification:
    • The US Centers for Disease Control and Prevention (CDC) classifies variants into three categories:
      • 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 B.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.
      • 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 B.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.
      • 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.
    • 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 B.1.617 lineage are designated as VUI.
  • Nomenclature:
    • Phylogenetic Assignment of Global Outbreak Lineages (PANGOLIN):
      • It was developed to implement the dynamic nomenclature of SARS-CoV-2 lineages, known as the Pango nomenclature.
      • It uses a hierarchical system based on genetic relatedness – an invaluable tool for genomic surveillance.
      • It uses alphabets (A, B, C, P) and numerals starting with 1. Variant lineages are at the emerging edge of the pandemic in different geographies. Lineage B is the most prolific.

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