Experts say the emergence of a new strain of the virus behind COVID-19 shouldn't be anything to worry about - but nothing can be certain until more data is collected.
UK Health Secretary Matt Hancocks says more than 1000 cases of the mutated SARS-CoV-2 virus have been found in the south of the country, and could be behind the recent rapid rise in infections in "London, Kent, parts of Essex and Hertfordshire".
According to the latest data on the UK government website, the virus' reproduction number in London and southeast England could be above one - meaning the outbreak is getting larger, despite the strict lockdown across the region.
There are fears the new variant could make existing vaccines less effective too. The UK last week was the first country in the world to approve the rollout of the Pfizer-BioNTech vaccine, but the mutation is on the virus' spike protein, which is also the region targeted by the vaccines.
A previous mutation - known as D614G - made the virus more infectious, but no deadlier.
So what do the experts make of this latest adaptation?
More infectious? Deadly? What the mutation might do
Lucy van Dorp of the UCL Genetics Institute in London said it depends exactly what the change is, with observations at her lab suggesting there are two possibilities - one which has been linked to increased infectivity, the other to lowered antibody response.
"At the same time it is important to remember that all SARS-CoV-2 in circulation are extremely genetically similar to one another and our prior should be that most mutations have no significant impact on the transmissibility of SARS-CoV-2."
Just because a virus becomes more infectious doesn't necessarily mean that it's deadlier to individuals who catch it.
"[D614G] did not make the virus more virulent, and should not affect vaccines or treatments, but did seem to make the virus slightly more easily spread from one person to the next," said Martin Hibberd of the London School of Hygiene & Tropical Medicine. "This has meant that strain is now the most common variant seen in many parts of the world."
Simon Clarke, associate professor of cellular microbiology at the University of Reading, said it would be of "grave concern" if the latest mutation made the virus more infectious, even if it wasn't any deadlier.
"While Hancock states that there is 'nothing to suggest' this variant will cause more serious disease, if it spreads more readily than other versions, infecting more people, it could eventually take a bigger toll on human health."
Many experts praised the UK's health service for picking up the new variant so early, allowing research into whether it is indeed more infectious, any deadlier, or more resistant to vaccines it could be.
"It is important to keep a calm and rational perspective on the strain as this is normal virus evolution and we expect new variants to come and go and emerge over time," said microbiology professor Alan McNally of the University of Birmingham. "It's too early to be worried or not by this new variant, but I am in awe of the surveillance efforts in the UK that allowed this to be picked up so fast."
Could this render the vaccines obsolete already?
Mutations are common when a virus infects a new species, but SARS-CoV-2 doesn't appear to mutate as often as viruses like influenza, which change so far they require a new vaccine every year. The first batch of COVID-19 vaccines surprised even their developers with how effective they were in trials.
"This virus doesn't mutate as fast as influenza and, although we need to keep it under surveillance, it will not be a major undertaking to update the new vaccines when necessary in the future," said viral immunologist Zania Stamataki of the University of Birmingham.
"Just because there has been a small change in the virus’ genetic make-up this does not mean it is any more virulent, nor that vaccines won’t be effective," said Tom Solomon, zoonotic virus expert at the University of Liverpool. "Our experience from previous similar viruses suggests that the vaccines will be effective despite small genetic changes."
Vaccines are usually designed to target several sites on a pathogen at once, so even if one section mutates, it can't escape. The chances of a virus evolving defences against several attack vectors at once are "almost impossible", Penn State University experts Andrew Read and David Kennedy wrote in an article for The Conversation in November.
The Pfizer-BioNTech vaccine works by getting the body's own cells to produce the virus' spike protein - on its own incapable of causing COVID-19 - teaching the immune system what it looks like, so it can react if it ever encounters the real thing. It's a new technology - known as mRNA - that's never been used in an approved vaccine before, but passed its phase III trials with flying colours.
"The vaccine produces antibodies against many regions in the spike protein - it is very unlikely a single change would make the vaccine less effective," said University of Bristol viral specialist Andrew Davidson.
But like the flu, vaccines could become less effective as the mutations build up - like what happens with influenza.
"We have no evidence at the moment whether this variant will or won’t respond to the vaccine," said Julian Hiscox, chair in infection and global health at the University of Liverpool.
"This illustrates that we need to be agile and flexible with the vaccine platforms and will probably be like seasonal influenza viruses where we have to give multiple vaccines that change with time."
The good news is if the vaccines need to be regularly updated, mRNA technology doesn't require much time. Once you have the mutation's genetic code, new vaccines can be synthesised very quickly - the Pfizer-BioNTech vaccine, as well as one made by startup Moderna, were developed in a matter of days after Chinese scientists released the original SARS-CoV-2 genetic code back in January.
You also don't need to grow attenuated viruses and proteins to inject into people - as mentioned above, the vaccines teach your body how to make them.
"With traditional vaccines, you have to do a lot of development. You need a big factory to make the protein, or the virus, and it takes a long time to grow them," Moderna founder Robert Langer told MIT News last week.
"The beauty of mRNA is that you don’t need that. If you inject nanoencapsulated mRNA into a person, it goes into the cells, and then the body is your factory. The body takes care of everything else from there."
