Alarm bells over a fresh spike in Covid cases in India - 1.35 lakh have been reported in the past 72 hours and the active caseload has increased for a 14th straight day - began ringing Wednesday as the government said a new "double mutant" variant of the virus, which was detected first in Maharashtra's Nagpur in December last year, had now spread to 18 states.
At a briefing this evening the Health Ministry said that, so far, the bulk of infections linked to this strain - around 20 per cent - have been reported from Maharashtra - 206 cases. Cases have also been reported from Delhi, Gujarat and Punjab, among other places, the ministry added.
So the big question now is this - what, exactly, is a "double mutation"?
NDTV spoke exclusively to Dr Rakesh Mishra, the Director of Center For Cellular & Microbiology, in Hyderabad, where this particular variant was first sequenced.
"Mutations in viruses are common.. but most are insignificant and do not cause any change in its ability to transmit or cause infections. Some though, like the ones in the United Kingdom or South Africa, can make the virus more infectious and, in some cases, even deadlier," Dr Mishra said.
Simply put, a 'double mutation' is when two mutated strains of a virus come together to form a third strain. The one reported in India is the result of the E484Q and L452R strains combining.
The L452R strain is found in California in the United States and the E484Q strain is indigenous.
A 'double mutation' potentially allows the virus to escape from the body's immune system and make itself more resistant to our antibodies. In some cases, the virus can also defend itself from the vaccine.
So is the combined strain more infectious or deadlier than its constituents, or any other strain?
"The new strain is efficient... but it is not yet a superspreader. (There is) no reason to believe that it is more deadly, just yet... but more investigation is required to understand this," Dr Mishra said.
"So far there is no reason to believe vaccines in India - Covishield and Covaxin - will not work against these new strains. But experts say the time has come to bring more vaccines to India... Vaccines developed by Pfizer and Moderna have better efficacy rates and have been proven to act against the new strains... this is the need of the hour," he added.
Last month AIIMS chief Dr Randeep Guleria told NDTV that the vaccines currently deployed in the country should work against the new strains as well. This was after Bharat Biotech, the makers of Covaxin, said its drug had been found effective against the UK strain.
The nationwide vaccination drive began January 16. On Tuesday the centre said it would enter the third phase on April 1, in which people over 45 can get the vaccine.
India has, so far, reported over 1.17 crore Covid cases since the pandemic began in December 2019.