A new strain of coronavirus dubbed Delta Plus has emerged, but experts say it is still too early to determine whether it is more infectious or severe than other variants.
The Government and Public Health England are currently monitoring the variant, Downing Street said.
So far, the UK has recorded 41 cases of the mutant strain since it was identified in the country on April 26.
The Prime Minister's official spokesman said PHE had already put extra measures in place where the variant had been detected including "enhanced contact tracing, testing, and isolation".
Here is all we know about the variant.
What is Delta Plus?
Delta Plus is the B.1.617.2 variant of the virus which causes Covid-19, with the addition of K417N mutation in the spike protein of the virus.
It is also referred to as AY.1. It has not been declared a variant of concern by the UK.
However, experts have said the virus will continue to mutate and some new variants could be more transmissible.
Is it more transmissible than other strains?
Because there haven't been many cases of the variant, experts have not been able to determine whether Delta Plus is more transmissible than other strains.
There have been some suggestions that it might evade protection from vaccines because of the mutation it is carrying, but this cannot be confirmed due to the low number of infections recorded so far.
It is also not clear if it will lead to more hospital admissions and deaths.
When was it identified for the first time?
It was first observed in India on April 5 and has been found in several countries, including the UK.
Around 160 cases have been identified globally, explained Francois Balloux, professor of computational systems biology and director at UCL Genetics Institute.
Britain said its first five cases were identified on April 26 and they were contacts of individuals who had travelled from, or transited through, Nepal and Turkey.
Where in the UK have Delta Plus cases been found?
The South East has reported the most cases (15), while the East of England, North East and Yorkshire and Humber regions have had not had any confirmed or probable cases.
The latest regional breakdown is as of June 14, when 36 cases had been confirmed and two were probable.
- South East - 15
- West Midlands - 10
- London - 4 (plus two probable cases)
- North West - 3
- South West - 2
- East Midlands - 1
- Unknown region - 1
- East of England - 0
- North East - 0
- Yorkshire and Humber - 0
Which other countries reported cases of the variant?
AY.1 was unofficially labelled the "Nepal variant" after it was found in 13 people who had travelled from Nepal to Japan, but the exact origin is still a mystery.
As of June 16, cases were reported in the following countries:
- United States - 83
- Portugal - 22
- Switzerland - 18
- Japan - 15
- Poland - 9
- India - 8
- Nepal - 3
- Canada - 1
- Russia - 1
- Turkey - 1
According to some experts, it was also found in China.
What other variants are being monitored in the UK?
Other variants being monitored in the UK are Alpha, Beta and Gamma.
Alpha was first identified in Kent and was the first variant of concern to spread rapidly around the world.
It was found to have a significant transmissibility advantage over the original virus.
Beta was first identified in South Africa and appears to have emerged around the same time as the variant originating in the UK.
Experts are also monitoring the Gamma variant, also known as P.1. which was first detected in Manaus, Brazil, and in travellers in Japan from Brazil.
