A variant of Covid-19 in India had led to a surge in cases in the country, prompting the UK to add the country to its red list of travel destinations.
It means Brits who have been to India in the last 10 days need to quarantine in a hotel for 10 days after arriving in the UK. Non-UK residents who have recently been to India are barred from entering the country.
Prime Minister Boris Johnson has also cancelled his trip to the country next week.
The variant first identified in India is now present in the UK too – so how worried should we be?
What are variants?
Viruses constantly change through mutation, and the emergence of new variants of coronavirus is a natural part of this process.
Some variants will emerge and then disappear, while others persist and can have worrying mutations.
So far we’ve seen plenty of variants, and they’re commonly referred to by where they were first identified – Kent, South Africa, and Brazil are all examples.
Why are some variants concerning?
Scientists are particularly concerned about variants of coronavirus that have key changes in the spike protein of the virus – meaning they could be more resistant to vaccines or antibodies in people who have had another strain of Covid.
One mutation of particular concern in this area is called E484K.
Variants of concern with the E484K mutation seem to spread more easily and more quickly than other variants, which may lead to more cases and, subsequently, more death.
Some variants may also cause more severe disease.
Which ones are in the UK?
To date, Public Health England (PHE) has seven variants under investigation (VUI), including the one from India – of which 103 cases have been identified in the UK.
A VUI is a variant that is being closely examined by experts to see whether it is more deadly, can transmit more easily or may evade vaccines.
If it meets any of these criteria, it moves from being under investigation to become a variant of concern (VOC).
There are currently four variants of concern in the UK: the Kent variant with a specific E484K mutation, the Brazilian variant (carries E484K) and the South African variant (carries E484K).
Investigations are ongoing into the cases of the Indian variant found in the UK, with some of the cases not linked to travel.
But experts say they they don’t yet have enough information about its transmissibility, severity or ability to evade vaccines.
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Do vaccines work against variants?
The picture is currently unclear, although most experts say the current range of vaccines in use should offer some protection against variants.
Studies are ongoing and Public Health England (PHE) is expected to say more about vaccine effectiveness against variants in the future.
Pfizer has published research suggesting its jab could offer good protection against the Brazilian and South African variants, and early results from Moderna suggest its vaccine has some effectiveness against variants.
AstraZeneca has also said it hopes its vaccine will protect against severe disease from any variant.
According to the World Health Organisation (WHO), all Covid-19 vaccines elicit a broad immune response involving a range of antibodies and cells, so changes or mutations in the virus should not make vaccines completely ineffective.
If vaccines are found to have very little effect, then new vaccines can be created to protect against variants. Most of the firms that produced initial vaccines are already working on a new range of jabs.
Are scientists worried about the situation in India?
Some are, yes, and had been calling for India to be put on the “red list” for travel – before the government took action on Monday.
Danny Altmann, professor of immunology at Imperial College London, said the variant of coronavirus first identified in India is likely to become a variant of concern.
However, Dr Jeffrey Barrett, director of the Covid-19 Genomics Initiative at the Wellcome Sanger Institute, said that while the variant should be watched carefully, it is “probably not at the top tier of mutations that generate the most concern”.
He said it was not yet known whether the variant was driving the current wave of infections seen in India.
Professor Andrew Hayward, who is on the Scientific Advisory Group for Emergencies (Sage), said the “evidence of increased transmissibility and escape from immunity is circumstantial” for the Indian variant.
But said he would “err on the side of caution” and “act sooner rather than later” when it comes to imposing increased travel restrictions.