Graph shows terrifying rise of new strain
A mutant strain of the coronavirus has caused panic in Europe where more than two dozen countries have suspended United Kingdom flights in fear of the new variant.
The UK confirmed the existence of the more infectious strain on Saturday (local time), citing it as one of the reasons Britain has had to effectively cancel Christmas.
Dozens of countries from India to Argentina have banned flights from Britain over concerns about the new virus strain, which is reportedly 70 per cent more contagious.
The mutation, known as the 501Y variant, has also been detected in small numbers elsewhere including in Australia, but experts say there is no evidence it is more lethal or resistant to vaccines.
Scientists are not sure where the strain first appeared, but many suspect Britain is ground zero.
The first known case there was sampled on September 20.
"It is very likely that it emerged here, but it is also likely that it is in other countries," Susan Hopkins, a senior lecturer in infectious diseases at Imperial College London, told journalists in a Zoom press conference on Monday.
Denmark, The Netherlands, Australia and Italy have all reported cases, she said.
A variant with some of the same genetic deletions has also been identified in South Africa, but is thought to have evolved separately, which supports the idea that viruses mutate to help them to become more effective at infecting others.
It is also possible, scientists say, that the mutation is already more widespread than thought but has simply not been detected.
The only way to spot a mutated version of SARS-CoV-2 is to sequence the virus's entire genome, but Denmark and Britain are the only countries in Europe that do so on a routine basis.
"The UK may be victims of their own technical success in highlighting the emergence of the 501Y variant," London School of Hygiene and Tropical Medicine Professor Brendan Wren said, noting that Britain may be treated "as the lepers of the world".
Members of NERVTAG, a group of scientists advising the British government on the threat posed by emerging respiratory diseases, said on Monday they are unlikely to trace the strain - officially known as SARS-CoV-2 VUI 202012/01 - back to a "patient zero", but have an idea of how it might have emerged.
"The hypothesis would be that this passed through somebody immunosuppressed who therefore had circulation of live mutations over a long period of time," NERVTAG chair Professor Peter Horby said.
The World Health Organisation in Europe said its experts would meet on Wednesday to discuss how to handle the outbreak, saying "limiting travel to contain spread is prudent until we have better info" but cautioned that "supply chains for essential goods and essential travel should remain possible".
Over the weekend, WHO Europe urged stronger action to contain the new strain and called on members to "increase the sequencing of SARS-CoV-2 viruses where possible and sharing of sequence data internationally, in particular, to report if the same mutations of concern are found".
The WHO's European region comprises 53 countries, including Russia and several Central Asian nations - a region that has registered nearly 24 million coronavirus cases and over 500,000 deaths.
WHAT ABOUT THE SECOND NEW VARIANT FROM SOUTH AFRICA?
Britain on Wednesday introduced restrictions on travel from South Africa over the spread of another new variant of coronavirus.
The restrictions, which applied with immediate effect, were introduced following the discovery of two cases of the virus strain in Britain.
"This new variant is highly concerning, because it is yet more transmissible, and it appears to have mutated further than the new variant that has been discovered in the UK," UK Health Minister Matt Hancock said, referring to a strain of the virus discovered in Britain which has also been found to be more contagious.
The health minister said that all individuals in the UK who had contracted the variant originating in South Africa had been placed in quarantine as well as their close contacts.
In addition to the travel restrictions, Hancock said the government was also asking anyone who has been in close contact with someone who had been in South Africa in the last two weeks to quarantine.
"They must restrict all contact with any other person whatsoever," he said.
The discovery of cases of what officials believe is a new, more transmissible variant of the coronavirus in the UK follows the announcement last week that a new strain had spread throughout the south of England.
HOW HAS THE NEW STRAIN CHANGED?
Whether the coronavirus is successful in finding someone to infect depends on how its "spike protein" interacts with a specific receptor on the surface of many human cells known as ACE2.
The easier it is for the virus to latch on to a receptor, the more likely it is the person will be infected.
The 501Y variant may have changed in ways that enhance its chances of a successful docking.
"There is a really unusual cluster of mutations associated with this variant - 22 coding changes across the whole virus genome," NERVTAG member and infectious diseases expert Professor Wendy Barclay said.
Mutations observed in the spike protein, she told journalists, "would make it easier for the virus to enter cells, and could biologically explain an increase in transmission".
Bits of missing genetic code in other regions could also boost its ability to spread, she said.
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HOW MUCH MORE INFECTIOUS?
In announcing more stringent lockdown measures over the Christmas holiday, British Prime Minister Boris Johnson said on Saturday the new viral strain "may be up to 70 per cent more transmissible than the original version of the disease".
That assessment was based on preliminary data from sequenced virus genomes gathered from London and parts of southeastern England.
In early November, scientists found the new variant was responsible for just over a quarter of infections in these areas. By the week ending on December 9, it accounted for more than 60 per cent of all new cases.
Since Mr Johnson's shock announcement, which triggered commercial flight bans and border closings, scientists in Britain have crunched even more data.
"We now have high confidence that this variant does have a transmission advantage over other virus variants that are currently in the UK," NERVTAG chair Professor Peter Horby said.
The latest calculations, he added, suggest 501Y is 50 to 70 per cent more infectious.
Another indicator of its ability to spread is the variant's reproductive number, or "R rate" - the average number of new cases generated by a single infected person.
Anything above 1.0 means that a virus is continuing to find new hosts and is expanding.
"Even during the (recent) lockdown in England, this virus had an R-number that was about 0.4 larger than non-variant strains," NERVTAG member Neil Ferguson said.
"The non-variant strains had an R number of about 0.8, but this variant had an R of 1.2 or even higher."
That could be bad news for efforts to curb the spread of COVID-19, which has already claimed more than 67,000 lives in Britain and 1.7 million worldwide.
"I think it is highly likely to become the dominant strain across the UK given the trends we have seen so far," Prof Ferguson said.
The World Health Organisation (WHO) on Tuesday said that "initial analysis indicates that the variant may spread more readily between people," but said more research was needed to assess its impact on treatments and vaccines.
IS 501Y MORE SEVERE?
"There is no indication at this point of increased infection severity associated with the new variant," the European Centre for Disease Prevention and Control (ECDC) said in its threat assessment.
This conclusion, however, "is challenged by the fact that the majority of cases were reported in people under 60 years old, who are less likely to develop severe symptoms".
At the same time, "there is a hint that it has a higher propensity to infect children," Prof Ferguson said.
Even if proven true, that does not mean the virus is "targeting" children, who up to now have been less prone to infection and, when they do catch the bug, less severe symptoms, Prof Barclay said.
"The previous virus had a harder time binding to ACE2 and getting into (human) cells," she explained. That made adults - with more abundant ACE2 receptors in their nose and throats - an easier target compared to children.
"If the new strain is having an easier time of entering and binding to cells, that would put children on a more level playing field," Prof Barclay added, noting the additional impact of young people mixing socially, especially in school.
WILL VACCINES STILL WORK?
Scientists in Britain and elsewhere are testing the new strain against the several vaccines, but so far there is no indication that they will be less effective.
"It is possible that we may need to update vaccines, perhaps not every year," Prof Barclay said. "But we will need to monitor these viruses moving forward."
Updating the new generation of so-called messenger RNA vaccines, she added, will be a lot easier than modifying flu vaccines, as happens every year.
Both of the leading vaccines in Europe and the US - one made by Pfizer-BioNTech, the other by Moderna - are RNA-based.
The co-founder of BioNTech, Ugur Sahin, said on Tuesday it was "highly likely" that its vaccine would work against the mutated strain detected in Britain, adding that the company could adapt the vaccine if necessary in six weeks.
Researchers are also investigating the possible impact of the new strain on COVID-19 testing and treatments, though there is little so far to suggest either will be significantly compromised.
"We have to be cautious in our conclusions, this is still early days and there's still a lot of uncertainty about many aspects of this new variant," Prof Ferguson said.
The European Union was preparing its rollout of the Pfizer-BioNTech vaccine on Sunday, following similar vaccination campaigns in the UK and the US.
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HOW OFTEN DO VIRUSES MUTATE?
All the time, but some viruses do it more than others.
A two-dose vaccine against measles, for example, can last a lifetime, whereas the cocktail in flu shots changes every year to keep up with genetic changes.
Coronaviruses are somewhere in between and SARS-CoV-2, is no exception.
"Viruses constantly change through mutation and the emergence of a new variant is an expected occurrence and not in itself a cause for concern," the ECDC said on Sunday in an threat assessment report of the new strain.
As for the pathogen that causes COVID-19, "even by March, there were eight major lineages that were all separating," Prof Hopkins said.
The more critical question is where in the virus such mutations occur, and whether they will make it more infectious and/or deadly.
Before the emergence in Britain of this more contagious strain, other genetic variations were mostly benign.
Originally published as Graph shows terrifying rise of new strain