The Hindu explains | Will the new ‘double mutant’ strain of coronavirus found in India lead to a further rise in infections?

The story so far: The National Center for Disease Control (NCDC), a unit of the Department of Health and Family Welfare, reported this week that a unique “double mutant” variant of the new coronavirus has been discovered in India. It has been reported in around 200 cases in Maharashtra, and some in Delhi and the Punjab. The NCDC also said that around 771 cases of variants of concern (VOCs) have been detected in more than 10,000 samples shared by states and union territories.

When did mutations start to emerge?

The emergence of new mutations in the novel coronavirus is normal. Variants spark scientific interest when scientists sequence virus genomes from RT-PCR positive samples from a diverse population and compare changes in genetic structure to original strains since the start of the pandemic of COVID-19. Often there are changes in the genetic alphabet that seem to give the virus a better evolutionary advantage to be able to continue to spread in the population. Some of these changes confer a huge advantage and become the dominant variant. Thus, a mutation called D614G in the early stages of the pandemic appeared last year, involving aspartic acid (D) in the 614th position of the amino acid replaced by glycine (G). This gave the virus a significant advantage in gaining more efficient entry into the body. It appeared that before March 1, 2020, only 10% of the world’s 997 genomic sequences had the mutation, 67% of the sequences between March 1 and March 31, and 78% of the sequences between April 1 and May 18. had.

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What are the existing mutant combinations?

As new variants evolve, scientists are starting to assess whether certain combinations of mutations are more likely. An N501Y mutation last year was independently reported in South Africa and Australia, and in the UK it was correlated with a triple spike in cases last December, where half of the cases carried it. N501Y allowed the spike protein of the virus to take root better. The “British variant” (B.1.1.7), as it came to be known, had at least 14 key mutations. However, another key mutation, E484K, which helped the virus bypass the immune system more frequently, has also started to gain traction. Together, these two mutations began to appear frequently in South Africa and were correlated with a large peak. It became the “South African” variant, B.1.351.

These two variants, along with another called the Brazilian variant (P.1), due to their spread, infectivity and ability to reduce vaccine efficacy somewhat, are the only ones internationally referred to as “ variants of concern. (VOC).

How important is the “double mutant” variant?

The double mutant variant reported by NCDC has the simultaneous presence of two mutations – E484Q and L452R – which have been independently found in other variants in several countries associated with local outbreaks. This latter mutation has been individually linked to local epidemics in California, United States, and has been shown to escape monoclonal antibodies (antibodies made in a lab with a niche targeting mechanism) produced in response to a COVID-19 infection. It has also been linked to increased infectivity.

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E484Q can escape four types of monoclonal antibodies and even some polyclonal antibodies derived from the blood serum of COVID-19 patients. So far, no one knows how the combined presence of these mutations would work. So far, around 10,787 Indian genomes have been sequenced and around 200 samples in Maharashtra contained the variant with the mutation, as do a handful in Delhi and Punjab.

The increase in the number of cases – now over 60,000 a day – especially in these states has led to speculation whether it is due to mutant strains. But we haven’t done enough to establish it. For this, genome samples from a district or cluster reporting a peak in cases should be sequenced and then compared to whether a significant fraction of them have the mutations of interest.

However, experts believe that the UK variant (B.1.1.7) may be of more concern. As of March 23, the variant has spread to a total of 125 countries in the six WHO regions and is the dominant strain in Britain. It has also been reported to have a higher death rate of over 60%, according to the WHO. Earlier this week, the NCDC said about 81% of the 401 samples sent for genome sequencing from the Punjab contained the UK variant.

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“This variant is more likely to contribute to an intense second wave,” said Jeremy Kamil, virologist at Louisiana State University Health Sciences Center Shreveport. BBC recently.

What does this mean for public health?

Very few so far. As the NCDC and the Department of Health point out, the standard prescription to wear masks, avoid potential super-spread events, and get vaccinated, if eligible, remains the best defense against variants of the disease. virus.

Threatening variants emerge from the increased opportunity for the virus to replicate and reduced opportunity remains the best defense. A consortium of 10 laboratories in India, called Indian SARS-CoV-2 Consortium on Genomics (INSACOG), sequenced a proportion of samples positive for RT-PCR and 771 were found positive for three VOCs – United Kingdom, Africa from the South and Brazilian strains.

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The new combination of variants in India has yet to receive a formal lineage name. Once this is done, there will be studies that will seek to establish its frequency and association with the relapses in the cases. Then there will be studies that will check if the variant makes the available vaccines less effective or if they are related to serious illness. Based on what they reveal, we may have a “variant of concern” only associated with India.