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Explained: Is the 'double mutant' coronavirus variant responsible for Maharashtra surge?

61 per cent samples in a Maharashtra study showed the double mutation phenomenon

nasal-spray-coronavirus-pixabay Representational image | Reuters

In the last week of March, when cases began to rise in the country, the Union health ministry had said that a new "double mutant" variant of SARS-CoV-2 was detected in Delhi, Maharashtra and some other places. This was in addition to the three "variants of concern"—emerging out of UK, South Africa and Brazil—that were reported in at least 18 states and Union territories. It was the National Centre for Disease Control (NCDC) who first announced that a new variant had been identified in samples of saliva taken from people in Maharashtra, Delhi and Punjab. The genome sequencing carried out by Indian SARS-CoV-2 Consortium on Genomics (INSACOG), a consortium of 10 labs in India, identified two important mutations in the variant dubbed as "double mutant". So far, the double mutant has been reported from countries across the world.

Simply put, the double mutant in India, identified as B.1.617, carried two mutations—E484Q and L452R—in the crucial spike protein part of the pathogen. This increases its transmissibility and ability to bypass the immune response. 

The double mutant was reported in 15-20 per cent of cases analysed from Maharashtra, the state which accounts for lion's share of coronavirus cases in the country. At that point of time, there was no clear indication of its role in the Maharashtra surge. Now, The Indian Express has reported NIV data showing that, of 361 COVID-19 samples taken in Maharashtra from January to March, 61 per cent had the double mutation. The publication quoted Dr Shashank Joshi, member of the state Covid task force as saying: “Entire families are getting infected. This is something we flagged two months ago. This variant is fast spreading, has exponential growth and has strained our health system. And we need district-wise sequencing to understand local viral behaviour.”

What is the double mutant virus, and what are its dangers?

When SARS-CoV-2, the novel coronavirus, enters your body, it binds itself to tissues with high concentration of angiotensin-converting enzyme II (ACE2), high levels of which are present in the lungs. ACE2 is a receptor on the surface of the cells, connecting the outside through the cell membrane to the insides of the cell. The S-protein on the surface of the virus (the same ones that give the virus its signature crown shape) bind to the ACE2 receptor. The double mutation B.1.617, according to multiple reports, trigger changes in the spike protein that make it more infectious to humans. The two mutations make it more difficult for the immune system to recognise the coronavirus. 

Both the E484Q mutation (reported in both UK and South African variants) and L452R mutation (found in the California strain) have been associated with much greater binding and antibody escape capabilities. 

However, the effect of the double mutation should not be overstated. So far, all vaccines in circulation have been reported to be effective against all kinds of virus variants, and the ongoing surges have not been empirically linked to the B.1.617 mutation. 

Centre rings the alarm bell on COVID surge

People not adhering to COVID-appropriate behaviour and the circulation of highly infectious strains of SARS-COV-2 could be the primary reasons behind the surge in coronavirus infections in India, AIIMS Director Dr Randeep Guleria said. He also warned that if the situation is not reversed, then the galloping infection rate will eventually cause a huge strain on the country's healthcare system. He sought stricter enforcement of COVID-appropriate behaviour on the ground level by the administration and authorities.

"Around February, when cases started to decrease, people became lax towards following COVID-appropriate behaviour as they thought the virus had become ineffective. "People are taking the disease lightly now. If you go out, you see that marketplaces, restaurants and shopping malls are crowded and full of people and these all are super-spreader events," Guleria said.

Earlier, if one sick person was able to infect around 30 per cent of their contacts, this time those getting the disease are infecting a larger number of people, he said. "So, the rate of spread of the infection is fast possibly due to the highly infectious and transmissible strains circulating," he added. Various strains of SARS-CoV-2, including the UK, South Africa and Brazil variants, are circulating in India and have been termed as highly transmissible by experts. Guleria said the entire humanity is going through a difficult time and "unless it is important, people should not venture out. Also, it has to be ensured that there is no gathering and stricter enforcement of COVID-appropriate behaviour has to be ensured".

"We may lose the gains we have made so far if we do not pay heed now," and the situation may completely get out of control, he said. "If the situation is not reversed, then the galloping infection rate will eventually cause a huge strain on the healthcare system also," he stressed.

-Inputs from PTI

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