Hot on the heels of the UK variant and the South African variant, coronavirus has mutated again – this time morphing into an even more worrying version of the virus known as the Brazilian variant.
Ministers are so concerned they have banned travel from Portugal and South American countries.
Here is everything you need to know about the Brazilian variant.
What is the Brazilian variant?
There are actually two Brazilian variants. One – known as P.1 – was detected circulating in Manaus, northern Brazil, by scientists in December. This is the one the government is most concerned about.
It has several mutations in parts of the genetic code responsible for building spike proteins, which work like little grappling hooks to get into human cells.
Any changes to their design could make it easier for them to attach to human cells, while also making it harder for the immune system to get rid of the virus.
A second one - known as P.2. - has been spotted 11 times in Britain and carries a mutation which can bypass antibodies.
It is currently spreading around Rio de Janeiro and has been linked to two reinfection cases in Brazil.
Is it more dangerous than the UK and South African variants?
The Brazilian P.1 variant carries similar worrying mutations to the UK and South African versions, notably the N501 and E484 mutations that seem to allow it to transmit more easily.
But scientists are particularly concerned because it has emerged in a population that was already approaching herd immunity and should have been protected.
Research published last year suggested that 76 per cent of people in Manaus had contracted coronavirus by October – a level so high it should have severely limited onward spread of the virus.
However, the city saw an unexpected surge of new cases last month and has now declared a state of emergency, with hospitals reaching 100 per cent capacity.
A team of geneticists from South America, London and Edinburgh found that 41 per cent of cases in Manaus are now caused by the new variant.
Genetic sequencing has shown that at least one person who caught the virus in the first wave has been infected by the new variant, and scientists warned there had been a "rapid increase" of cases in locations where previous infection rates were thought to be very high.
They have said it is now essential to investigate "whether there is an increased risk of reinfection in previously exposed individuals".
Professor Sharon Peacock, the director of the Covid-19 Genomics UK Consortium, said the Brazilian variant was worrying because it shared mutation N501 with the UK variant, which is believed to have increased transmissibility between 50 and 77 per cent. It also had other mutations which stopped antibodies from working.
"The fact the virus has the N501 means we know that it's likely to be more transmissible, so that already rings alarm bells, and if it's then carrying other mutations which could have other properties then we clearly need to take it seriously. But we have the tools to detect this and the public health capabilities to prevent spread."
There is little evidence yet to show whether the second Brazilian variant P.2 is more dangerous than the UK or South African versions and British scientists have not classed it a ‘variant of concern.’
However it does carry E484 and is thought to have caused reinfections in people who have already recovered from coronavirus.
Is the Brazilian variant in Britain?
Professor John Edmunds, a member of SAGE, said it was "likely" that there are already cases of both Brazilian coronavirus variants in the UK, during an interview with BBC Radio 4 on Jan 16.
At present the P.1 variant has not been picked up in testing in Britain, and travel from countries at risk of passing on the new lineage has been stopped.
But Prof Edmunds sueggested it was "likely" some of the Manaus strain had entered Britain saying:"We are one of the most connected countries in the world so I would find it unusual if we hadn't imported some cases into the UK."
The second P.2 variant has been here ‘for some time’ according to scientists, and has been picked up in 11 genomes.
The UK variant, which was detected in September, has already spread to 35 countries and the South African variant was found in Britain in December.
Felipe Naveca, the deputy director of research at Fiocruz Amazonía, a major research centre in Manaus, recently warned that the P.1 variant is likely to become widespread.
"If these mutations confer any selective advantage for viral transmissibility, we should expect an increase in the frequency of these viral lineages in Brazil and in the world in the coming months," he said.
What are the symptoms of the Brazilian variant?
At the moment, it seems the symptoms for both Brazilian variants are the same as the more familiar strain.
The variants were spotted through polymerase chain reaction (PCR) tests which are usually only given to people with traditional symptoms of the virus, so we can assume the symptoms are identical.
Could it hamper a vaccine?
Possibly. Most coronavirus vaccines are targeting the spike protein which the virus uses to latch on to human cells. The vaccines prime the body to be able to spot the spike protein so the immune system can spot the virus.
However, if the spike protein mutates, the body will no longer be able to recognise the virus and vaccines may prove ineffective.
As well as not being able to spot the virus, the mutations may also mean that antibodies do not attach properly to the virus cells, making it more difficult to clear the infection from the body.
Scientists have already proved that the E484 mutation helps the virus to evade antibodies produced after an infection with coronavirus, raising the risk of a re-infection from the new variant.
Although Professor Andrew Pollard, director of the Oxford Vaccine Group, offered some hope on Jan 16, saying that the current vaccines should protect against the strains circulating in the UK.
He told Today: "As we look forward through 2021, we're going to see lots of new variants and we're going to have to get used to that.
"But the critical question is whether some of these new variants are adapting because of immunity amongst human populations - whether that is because of infection... or indeed as a result of vaccination."
However, he said that new variants were being detected early, and stressed: "If indeed we do need to make new vaccines we will be able to stand those up really quickly."
Some good news arrived on Jan 16, when The Telegraph exclusively reported that Britain would have the capacity to vaccinate the entire nation against new coronavirus strains within four months, once a “super-factory” opens this year.
The Oxfordshire-based facility, which is worth £158m, will produce 70m doses of an emergency vaccine in the UK, Dr Matthew Duchars, chief executive of the Vaccines Manufacturing Innovation Centre (VMIC), shared.
Speaking to The Telegraph, Dr Duchars revealed: “New Covid variants are absolutely part of the thinking. We probably will need to make seasonal vaccine variants because there may well be mutations in the virus, as well as vaccines for other diseases. You never know what’s coming next.”
What is the UK variant?
The variant, called "VUI – 202012/01", also carries a mutation to the gene that forms spike proteins. These are little grippy rods on the outside of the virus cell that attach to human cells.
It was picked up in Kent in September and scientists now believe it evolved inside an immuno-compromised person who was chronically infected for a long time. A report from Imperial College suggested the UK variant is between 50 and 75 per cent more infectious than the version which swept through the UK in the first wave.
Although it is unclear why this variant is more transmissable, the Government's Nervtag (New and Emerging Respiratory Virus Threats Advisory Group) has found that people infected with this version have higher viral loads in their throats and so may shed more infectious particles.
The new mutations may also make the virus better at attaching to human cells, so it is able to get into the body more quickly before the immune system can clear it away.
The mutated strain may more easily infect children and young people, and there are far more younger people being admitted to hospital in the second wave. Preliminary research suggests this is also due to its "stickiness".
Children have fewer of the receptors which the older coronavirus variant needed to get into cells, meaning they were less likely to catch it, but the new variant might compensate for lower levels of receptors or that door to the virus in children by being stickier, scientists have said.
What is the South African variant?
The South African variant, first spotted in Britain in December, has three mutations in important genes. One, the N501 mutation, has already been found in the UK variant and could be responsible for it being so infectious.
However, the South African version carries two more mutations (E484 and K417) that are absent in the British version and make it far more worrying.
"These two additional mutations may interfere more with vaccine effectiveness in the South African variant than in the UK variant," said Dr Julian W Tang, honorary associate professor and clinical virologist at the University of Leicester.
"This does not mean that the existing Covid-19 vaccines will not work at all, just that the antibodies induced by the current vaccines may not bind and neutralise the South African variant as well as they would the other circulating viruses, including the UK variant."
The South African variant carries mutations in a gene which builds spike proteins – the rod-like structures on the outside of the virus which attach to human cells
Worryingly, the mutation may also mean it is harder to pick up cases through the normal PCR testing, so it could have already spread widely. It quickly became the dominant variant in the Eastern and Western Cape provinces of South Africa.