Michelle Roberts
A new variant of coronavirus, first found in India in late 2020, has been discovered in the UK.
Health officials say the genetic changes it has undergone might make it more contagious - and past Covid infection or current vaccines may not offer full protection against it. More studies are needed to be sure.
What is the Indian variant?
There are many thousands of different versions, or variants, of Covid circulating.
More than 100 cases of the Indian variant (also known as B.1.617) have been confirmed in the UK. That may sound like a large number, but it is less than 1% of the Covid samples that have been analysed for their genetic make-up in the UK.
Public Health England says it appears a few of the cases are not linked to international travel. Investigations into how they were acquired are continuing.
Prime Minister Boris Johnson has cancelled a planned trip to India later this month and the country is being added to the government's travel ban red list to help prevent more spread.
However, there is not yet enough data to say the Indian variant is of a "variant of concern" - a term used to describe the UK, Brazilian and South African variants.
Or that it is directly responsible for the recent surge in Covid-19 cases being seen in India.
What about the UK, Brazilian and South African variants?
These strains of Covid-19 may be more contagious and dodge immunity to some extent.
- The UK or Kent variant (also known as B.1.1.7) now dominant in much of Britain, has spread to more than 50 countries and appears to be mutating again
- The South Africa variant (B.1.351) has found in at least 20 other countries, including the UK
- The Brazil variant (also known as P.1) has now been found in the UK
It's not unexpected that new variants have developed. All viruses mutate as they make copies of themselves to spread and thrive.
Most of these differences are inconsequential. A few can even be harmful to the virus's survival. But some can make it more infectious or threatening.
Are the new variants more dangerous?
There is no evidence that any of them cause much more serious illness for the vast majority of people who become infected.
As with the original version, the risk is highest for people who are elderly or have significant underlying health conditions.
For the UK variant there is some research suggesting it may be associated with a 30% higher risk of death. The evidence is not conclusive, however.
To prevent infection, it's important to be extra vigilant about washing your hands, keeping your distance from other people and wearing a face covering.
How do the new variants mutate?
The UK, South Africa, Brazil and Indian variants have all undergone changes to their spike protein - the part of the virus which attaches to human cells.
One mutation, called N501Y, shared by some of them, seems to make the virus better at infecting cells and spreading.
Experts think the UK/Kent strain may be up to 70% more transmissible or infectious - although research by Public Health England puts it between 30% and 50%.
The South Africa and Brazil variants have more potentially important changes in the spike protein.
They have a key mutation, called E484K, that may help the virus evade parts of the immune system, called antibodies, that can fight coronavirus based on experience from prior infection or a vaccine.
Experts recently found a small number of cases of the UK variant that have this change too.
The Indian variant has some potentially important mutations (E484Q, L452R and P681R) that might help it escape some immunity, which is why experts are urgently studying it.
Will vaccines still work against variants?
Current vaccines were designed around earlier versions of coronavirus, but scientists believe they should still work, although perhaps not quite as well.
A recent study suggests the Brazilian variant may be resisting antibodies in people who've already had Covid and should have some immunity.
However, early lab results and real life data suggest the Pfizer vaccine can protect against the new variants, although slightly less effectively.
Data from the Oxford-AstraZeneca vaccine team suggests it protects just as well against the new UK variant.
It offers less protection against the South Africa variant - but should still protect against severe illness.
Early results suggest the Moderna vaccine is effective against the South Africa variant, although the immune response may not be as strong or long-lasting.
Experts say with a new virus mutation, even in a worst case scenario, vaccines could be redesigned and tweaked in weeks or months to be better matches.
The UK Government has announced a deal with biopharmaceutical company CureVac to develop vaccines against future variants, with a 50 million dose pre-order.
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