Scientists have identified 16 cases of a new coronavirus variant in the UK, Public Health England (PHE) has announced.
Cases of the variant, referred to as VUI-202102/04, were first identified on February 15 through genomic horizon scanning.
PHE said on Thursday that all individuals who tested positive and their contacts have been traced and advised to isolate.
The variant, which is understood to have originated in the UK, was designated a "variant under investigation" (VUI) on February 24.
Variants of Covid-19 can be identified as VUIs or "variants of concern" (VOCs).
New variants emerge regularly and experts are conducting frequent analysis to see which are of concern, and which are not.
The latest identified variant, also known as B.1.1.318, contains the E484K mutation, which is found in two other VUIs present in the UK, but it does not feature the N501Y mutation that is present in all VOCs, PHE said.
The findings mean there are now four VUIs and four VOCs being tracked by scientists in the UK.
Other VUIs include one from Brazil, known as P2, which has had 43 probable or confirmed cases identified in the UK, but is not causing scientists serious concern.
PHE said that, as of Wednesday, a total of 26 cases of the P2 variant had been found in England where no travel links could be established.
Two further VUIs - dubbed A.23.1 with E484K and B.1.525 - have seen 78 and 86 probable or confirmed UK cases detected respectively.
Both were first detected in the UK in December.
Additional testing is currently being made available for targeted areas of England to suppress the spread of VOCs.
This includes surge testing in South Gloucestershire after cases of the Manaus variant of coronavirus were discovered.
This variant of concern - known as P.1 - was detected in Brazil and in travellers from Brazil to Japan, and was associated with a surge of cases in Manaus late last year.
Six cases of this variant of concern have been found in the UK - three in Scotland and three in England.
On Tuesday, the hunt for a missing person infected with the Manaus variant of coronavirus had been narrowed down to 379 households in the south east of England, Health Secretary Matt Hancock said.
Elsewhere, additional testing in targeted parts of London and Stockton-on-Tees, in County Durham, aims to suppress the spread of the South African variant of concern, which was first sequenced in the UK in December 2020.
PHE said that, as of Wednesday, a total of 59 cases of the South African variant have been found in England where there were no travel links.
Another VOC is the UK/Kent variant called B117 which was first detected in the UK and first sequenced in the country in September 2020.
A fourth VOC is the UK/Kent variant + E484K mutation, which was first detected in Bristol and is the B117 variant with the genetic change also found in both the South African and Brazilian VOCs, E484K.
What do we know about coronavirus variants?
There are currently four variants of concern:
- UK/Kent variant: First detected in the UK and was first sequenced in the UK in September 2020 and called B117.
- UK/Kent variant + E484K mutation: This variant was first detected in Bristol and is the UK variant (B117) with a genetic change also found in both the South African and Brazilian variants, E484K.
- South African variant: First detected in South Africa and first sequenced in the UK in December 2020.
- Brazilian variant: First detected in Japan in travellers from Brazil in January 2021 and has now been detected in the UK.
There is also a variant under investigation, a second variant from Brazil, that has been detected in a handful of cases in the UK, but is not causing scientists serious concern.
- The Brazilian variant
The first cases of the Brazilian variant of concern have been detected in the UK, three in England and three in Scotland.
Experts detected the new variant circulating in December in Manaus, north Brazil.
It is not yet known if the mutation causes more severe Covid-19, but evidence suggests it may be more transmissible.
Scientists are conducting analysis to establish if it has a higher mortality rate or if it affects the vaccines or treatments.
The variant was detected in Brazil and in travellers from Brazil to Japan, and contains a unique constellation of lineage defining mutations.
The P. 1 variant is associated with a surge of cases in Manaus late last year, which led to a severe second wave of Covid-19.
Scientists were concerned because this raised the possibility it is able more easily re-infect patients due to the mutations it carries. But the evidence for this is currently limited.
Like the South African variant, the Brazilian one carries a mutation in the spike protein called E484K, raising concerns that vaccines may not be as effective against it.
- The UK/Kent variant
This variant was first detected in Kent in September, and it has been suggested that its spread in December led to a rapid rise in Covid-19 cases before the second national lockdown was announced in England.
It is now thought to be the dominant variant in the UK.
Analysis of the variant, known as B117, suggests it is up to 70% more transmissible than the previous strain that was dominant in the UK.
Despite data suggesting the mutant variant may be more deadly, there is no evidence to indicate existing treatments, such as dexamethasone, will not be effective against it.
A study has suggested that people infected with the UK variant are less likely to report a loss of taste and smell.
The Oxford/AstraZeneca coronavirus vaccine has a similar efficacy against the variant, compared with the original strain of Covid-19 against which it was tested.
Studies also suggest the jab developed by Pfizer and BioNTech is effective against the UK variant of coronavirus.
The Moderna coronavirus vaccine, due to arrive in the UK in the spring, is effective against all emerging mutations of the virus that have been detected to date, according to the company.
- The UK/Kent variant + E484K mutation
This variant was first detected in Bristol and a handful of other cases have been identified across the UK.
It carries a genetic change also found in both the South African and Brazilian variants, E484K.
Analysis into this variant is ongoing, and researchers are looking at how vaccines might affect the strain.
- The South African variant
About 193 cases of this variant have been detected in the UK.
This variant carries the E484K mutation which experts suggest may be better at evading the human immune response.
The vaccine developed by Pfizer and BioNTech is effective against this variant, according to a study from the US.
However, a separate study found that the Oxford/AstraZeneca jab was not effective at preventing mild illness caused by the more infectious South African mutation.
But the jab will protect against deaths and severe disease amid the spread of the South African variant, according to researchers.
Why do viruses mutate?
There have been many mutations in Sars-CoV-2, the virus that causes Covid-19, since it emerged in 2019, some more significant than others.
However, this is to be expected as this virus is an RNA virus, like the flu and measles, and these tend to mutate and change.
Mutations usually occur by chance, and the pressure on the virus to evolve is increased by the fact that so many millions of people have now been infected.
Sometimes mutations can lead to weaker versions of a virus, and it could even be that the changes are so small they have little impact on how it behaves.
If new variants spread faster it means they are likely to infect more people, increasing the number of cases.
Viruses evolve in order to survive - mutations are a simple mistake that give the virus a chance to keep infecting people.