The detection of a "double mutant" variant of the coronavirus in India has led to renewed concerns about the emergence of new forms that will spread more easily and evade the body's immune responses.
This new variant – named a double mutant because it has two key mutations – is becoming more common, particularly in western parts of the country.
The National looks at the mutations the new version contains and considers the significance of its emergence on the pandemic.
What mutations does it contain?
Genetic analysis has found that the new variant contains two significant mutations in the spike protein – the part of the virus that latches on to human cells – known to scientists as E484Q and L452R.
These have arisen by the normal process of mutation, in which mistakes are made when genetic material is replicated.
E484K is called an escape mutation because it helps the virus evade immunity from previous infection or vaccination.
The other mutation, L452R, has also been found in samples of the coronavirus in the US, including in the “California variant”, which is thought to be more infectious.
In line with this, India’s Ministry of Health and Family Welfare said that the changes seen in the double mutant “confer immune escape and increased infectivity”.
Indians receive the Covid-19 vaccine
Where has the 'double mutant' been found?
Indian health officials said that a growing proportion of coronavirus samples from the west Indian state of Maharashtra, which includes India's largest city Mumbai, contained two significant mutations.
"These mutations have been found in about 15 to 20 per cent of samples, and do not match any previously catalogued VOCs [variants of concern]," a Ministry of Health and Family Welfare statement said.
Reports said the double mutant has also been detected in other Indian states such as Kerala, on the south-west coast, and Punjab, in the north-west, as well as in a small number of samples in Delhi, which contains the capital New Delhi.
In other parts of the world – such as the UK and mainland Europe – new variants, including the Kent or UK variant have caused case numbers to spike.
While case numbers in Maharashtra and India as a whole are currently increasing, the double mutant is not responsible – at least yet – for a majority of infections, so it is not thought to be behind the rises.
Should we be worried by the double mutant?
While the double mutant may be better able to spread and evade pre-existing immune defences, it does not appear to be more of a threat than some other “variants of concern” that have arisen so far.
Professor Paul Hunter, an infectious diseases specialist and professor in medicine at the University of East Anglia in the UK, described the new variant as "no different to the Brazilian and South African variants, albeit with different mutations.
“The big issue is whether ultimately it starts spreading and replacing pre-existing variants to become the dominant variant, but at the moment it’s a bit too early to say,” he said.
“I’m quite surprised about the fact they’ve made so much of it being a double mutant, because so is the South African variant, so is the Brazilian variant and, in fact, so is the Kent variant. Every variant of concern has multiple mutations.”
Could the double mutant mix with other variants to create an even more dangerous variant?
New mutations arise all the time and are likely to give rise to new variants of concern that, like the South African and Brazilian ones, might spread more easily and evade vaccines.
However, Mr Hunter said the mixing of genetic material between coronaviruses was rarer than with, for example, the viruses that cause influenza, so the exchange of mutations was less likely.
“It’s called recombination,” he said. “When we’re talking about influenza, it’s something that happens a lot and that’s what largely triggers flu pandemics.
“It’s got what’s called a segmented genome – its genetic material is broken up into smaller pieces.
The coronavirus is one big piece – it’s much more difficult for it to undergo recombination, [although] it’s certainly a possibility.”