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Why do Covid-19 variants cause so much concern?

Covid testing has been used to help prevent the spread of variants
Jane Kirby, PA

British prime minister Boris Johnson has cancelled his trip to India next week amid concern over the country's rising coronavirus cases and its Covid-19 variant, which is also present in the UK.

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.

Why are some variants concerning?

Scientists are particularly concerned about variants of coronavirus that have key changes in the spike protein of the virus.

Mutations in a specific region of the spike protein may allow the virus to evade or partially evade the effectiveness of vaccines or natural immunity. 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 of Covid-19 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 77 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. These are the variant first found in Kent, the Kent variant with a specific E484K mutation, the Brazilian variant (carries E484K) and the South African variant (carries E484K).

Dr Susan Hopkins, chief medical adviser for NHS Test and Trace, said at the weekend: "We have seen a couple of cases (of the Indian variant) that haven't arisen from travel but we're still trying to undergo the investigations to look in great detail at where they might have acquired it from.

"To escalate it up the ranking we need to know that it has increased transmissibility, increased severity or vaccine evading, and we just don't have that yet."

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.

Therefore, 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 have called for India to be put on the "red list" for travel, which means arrivals to the UK would need to quarantine in a hotel.

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.

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