By Michael Le Page
London, U.K – December 22, 2020: 4:48pm (NEW SCIENTIST): Many countries have closed their borders to people leaving the UK due to the rapid spread within the country of a new variant of the coronavirus that might be more transmissible. Meanwhile, South Africa is also reporting the spread of another new variant. Here’s what you need to know.
What do we know about the new UK variant so far?
B.1.1.7, as it’s known, has 17 mutations compared with the original SARS-CoV-2 virus first discovered in Wuhan, China, including eight that may change the shape of the outer spike protein. Many of these mutations have been found before, but to have so many in a single virus is unusual. It was first sequenced in the UK on 20 September, but only caught the attention of scientists on 8 December, when they were looking for reasons for the rapid growth of cases in southeast England. On 14 December, the UK’s health minister, Matt Hancock, told parliament that a new variant that seems to spread faster had been identified.
How worried should we be?
There is no evidence so far that the new coronavirus variant in the UK causes more severe disease or that it can evade the protection conferred by any of the vaccines. Some lines of evidence suggest that it spreads more readily, but the evidence isn’t conclusive. On 21 December, a UK expert committee on emerging viral threats said that they have “high confidence” that there is a substantial increase in transmissibility compared with other variants”. “There is still more data that we need to get to be 100 per cent sure of this,” says committee member Peter Horby at the University of Oxford.
How much faster is it thought to spread?
The latest estimate is that it was 50 per cent more transmissible than other circulating strains during England’s latest lockdown, according to Neil Ferguson at Imperial College London, another committee member. However, it is not clear if this figure is true more generally, he says. B.1.1.7 is already responsible for 80 per cent of infections in London.
What does it mean if this variant is better at spreading?
“No matter how the virus changes, it needs us to be close enough to each other and to have interactions to let it jump between us,” says Emma Hodcroft at the University of Basel in Switzerland. “If we don’t give the virus those opportunities, it simply can’t spread no matter what variant it is.” In other words, standard control measures such as wearing masks and social distancing will still work. The new, tighter “tier 4” restrictions introduced in some parts of England, for example, will be effective if people follow the rules. But imposing such restrictions is obviously highly undesirable.
How did we discover these variants?
Standard tests look for the presence of the virus. It is also possible to sequence the entire genome of the virus, which is around 30,000 RNA letters long, to look for any changes compared with previously sequenced samples. Researchers around the world sometimes sequence samples to track the spread of the coronavirus and see if it is evolving.
What is different about the UK variant?
The mutations that might change the shape of the spike protein may allow the virus to bind to receptors on human cells more strongly and thus get into cells more easily. This may increase viral replication in the upper airways – initial results suggest there are more viruses present on average in swabs from people infected with B.1.1.7 than with other variants. There are also “hints” that it is more likely to infect children, Ferguson says.
And the South Africa variant?
Around 90 per cent of infections in South Africa are now due to one variant, sequencing suggests, but much less is known about it. This variant, called 501.V2, also has 17 mutations, but only one is the same as in the UK variant. This particular mutation, called N501Y, has been around for a while – it was first seen in Brazil in April and has been detected in several countries since.
How unusual is it for the coronavirus to mutate?
Not unusual at all. In fact, there are tens of thousands of “mutants” that differ from each other by at least one mutation. But any two SARS-CoV-2 coronaviruses from anywhere in the world will usually differ by fewer than 30 mutations, and they are regarded as all belonging to the same strain. Researchers instead talk about different lineages.
Are the mutations in this variant helping it spread?
We don’t know. By chance, some coronavirus lineages do spread more than others. For instance, a variant first found in Spain spread rapidly across Europe in the summer. There was concern that this variant was both more transmissible and more dangerous, but this turned out not to be the case. Its rapid spread is now thought to be due to people travelling to Spain for holidays. However, Hodcroft, who studied the Spanish variant, thinks the UK variant really could be more transmissible. “There is an increasing amount of evidence that there might be a real difference here,” she says. “But nothing we have right now is conclusive.”
How do we find out for sure?
Health authorities will have to keep tracking variants to see if this variant spreads faster than others. Researchers also plan to carry out lab experiments to try to determine the effects of all the mutations. This will include testing antibodies from people who have been vaccinated or infected before to see if they are less effective against B.1.1.7.
Has the UK variant spread to other countries already?
Yes. So far, confirmed cases of B.1.1.7 have been reported only in Denmark and Australia, with possible cases in Belgium, Italy and the Netherlands. However, few countries do as much sequencing as the UK, so many cases could have been missed. Given that the UK variant was first detected in September, it is possible that it has already spread to many more countries – we should find out soon now health authorities around the world are looking for it.
So is it too late for travel bans to work?
They will still help, by preventing more introductions of the new variant and thus keeping down the number of cases and making them easier to control, says Hodcroft. “The goal here is more to buy time,” she says.
Can this variant be detected by normal tests?
The short answer is yes. However some tests may need to be tweaked. The standard test for the coronavirus involves looking for any of three parts of the viral genome sequence. By chance, in some tests used by major labs in the UK, one of the parts is one of the mutated bits of the UK variant. This has turned out to be very useful. By looking at tests results that came back positive for only two of the three parts – called S gene dropouts – health authorities have been able to get a much better idea of how fast the variant is spreading than would be possible from sequencing data alone.
Where did the UK variant come from?
“It very much looks like a point source in England,” says Susan Hopkins at Public Health England. In other words, it came from a single individual. There is speculation that it could have evolved in the body of a person with a weakened immune system, meaning the immune response wasn’t strong enough to kill off the virus but did force it to evolve. This would help explain why it has more mutations than normal.
Published online 15 December 2020 , updated 21 December 2020