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Covid-19: Delta Plus Variant

Posted on June 26, 2021 by admin1  32

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Recently, India has reported nearly 50 cases of Delta plus SARS-CoV-2 variant, with Maharashtra and Tamil Nadu leading with the maximum number of cases.

  • The Health Ministry has categorised Delta Plus variant of coronavirus as a ‘variant of concern’. 

About Delta Plus variant

  • Delta Plus (B.1.617.2.1/(AY.1) is a new mutant strain of the Delta variant of SARS-CoV-2 and has emerged as a new threat.
  • This strain is characterised by the K417N mutation in the spike protein of the SARS-CoV2 virus that causes the Covid-19 disease.
  •  The K417N mutation has been associated with “immune escape”, which means that the virus is less susceptible to — or less responsive to — any drug therapy.
  • The K417N mutation is within the receptor-binding domain of the spike protein, and this change is noteworthy because this mutation is also found in the B.1.351 or Beta variant of concern.
  • The combination of features from other, earlier variants could make Delta Plus adapt better to pull off an immune escape.
  • Transmissibility 
    • Experts believe Delta Plus has increased transmissibility but it is still not very clear as to how virulent this new strain is in comparison to other variants.
      • There is no indication yet of the severity of the disease due to the new variant.
  • The World Health Organization (WHO) has not classified it as a “Variant of Concern“(VOC) and scientists believe there is not enough evidence to support the claims of this variant being a ‘concern’.
    • WHO classifies a variant as a VOC when it is associated with an increase in transmissibility or detrimental change in Covid-19 epidemiology; increase in virulence; or decrease in the effectiveness of public health measures or available diagnostics, vaccines, therapeutics.
  • In the case of the Delta Plus variant, the Health Ministry identified three characteristics — increased transmissibility; stronger binding in receptors of lung cells; and potential reduction in monoclonal antibody response.

Delta variant  (B.1.617)

  • SARS-CoV-2 variant’s B.1.617 lineage was detected in India earlier this year, 2021. 
  • It’s sub-lineage B.1.617.2 is more transmissible than contemporary lineages.
  • The World Health Organization (WHO), which has given it the label Delta, has categorised it as a Variant Of Concern (VOC). 

What makes the Delta Variant a VOC?

  • Different variants are characterised by mutations — or alterations in the virus’s genetic material. 
  • An RNA virus, such as SARS-CoV-2, is made of about 30,000 base pairs of amino acids, placed like bricks next to each other.
  • An alteration in any of these bases causes a mutation, effectively changing the shape and behaviour of the virus. 
    • The Delta variant contains multiple mutations in the spike protein. At least four mutations are important.
      • L452R was first reported in Denmark in March 2020. 
        • This mutation has been found more transmissible than wild-type strains and also has been associated with reduced antibody efficacy and reduced neutralisation by vaccine sera.
      • The mutation P681R has been associated with chemical processes that may enhance transmissibility.
      • The D614G mutation was first documented in the US early in the pandemic, having initially circulated in Europe.
        • There is evidence that variants with this mutation spread more quickly.
      • Another mutation in Delta is T478K.
        • This was present in around 65 per cent of occurrences in variant B.1.1.222, first detected in Mexico last year and associated with higher infectivity.

 

Delta Plus Variant in World and  India

  • The Delta plus variant has been identified and isolated in over 10 countries and nearly 50 cases have already been seen in India, especially Maharashtra, which is already bracing for a third wave.
    •  In India, it was first reported in a Public Health England bulletin on June 11.
  • India warned that regions where it has been found “may need to enhance their public health response by focusing on surveillance, enhanced testing, quick contact-tracing and priority vaccination.”

 

Concerns 

  • Delta Plus is considered highly infectious.
  • There is a rising concern in some quarters following warnings by experts that Delta Plus may show resistance against monoclonal antibodies cocktail treatments such as the Roche and Cipla ones being marketed in India at steep prices (almost Rs 60,000 per dose).
  • One potential risk that has sparked unease among the medical community is that the new variant may be able to bypass immunity provided by both vaccine and earlier infection.
  • There are worries Delta Plus would inflict another wave of infections on India after it emerged from the world’s worst surge in cases only recently.

 

 Vaccines Effectiveness  Against the Delta Plus Variant

  • Medical experts say it is too early to predict the effectiveness of the existing vaccines on the new variant. 
  • A detailed study would be required to establish any effect of the mutant on the immune system. 
    • Studies are ongoing in India and globally to test the effectiveness of vaccines against this mutation.
  • However, the Union Health Ministry Secretary says that both Indian vaccines — Covishield and Covaxin are effective against the Delta Variant.

What is the Spike Protein?

  • It is a protein that protrudes from the surface of a coronavirus, like the spikes of a crown or corona hence called ‘coronavirus’. 
  • In the SARS-CoV-2 coronavirus, it is the spike protein that initiates the process of infection in a human cell.
  • It attaches itself to a human enzyme, called the ACE2 receptor, before going to enter the cell and make multiple copies of itself.

                                           Image Courtesy: The Economist 

 

What is a Mutation?

  • It means a change in the genetic sequence of the virus. 
  • In the case of SARS-CoV-2, which is an RNA virus, a mutation means a change in the sequence in which its molecules are arranged. 
  • A mutation in an RNA virus often happens when the virus makes a mistake while it is making copies of itself.
  • Only if the mutation results in a significant change in the protein structure can the course of the disease be altered.

Source: TH

 
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