A new variant of the pandemic SARS-CoV-2 coronavirus is spreading rapidly in Britain and prompting high levels of concern among its European neighbors, some of which have cut transport links.
The strain, referred to by some experts as the B.1.1.7 lineage, is not the first new variant of the pandemic virus to emerge, but is said to be up to 70 percent more transmissible than the previously dominant strain in the United Kingdom.
Are the concerns justified?
Most scientists say yes. The new variant has rapidly become the dominant strain in cases of COVID-19 in parts of southern England, and has been linked to an increase in hospitalization rates, especially in London and in the adjacent county of Kent.
While it was first seen in Britain in September, by the week of Dec. 9 in London, 62 percent of COVID-19 cases were due to the new variant. That compared to 28 percent of cases three weeks earlier.
The governments of Australia, Italy and the Netherlands say they detected cases of the new strain. It was identified in the Netherlands in early December.
A few cases of COVID-19 with the new variant have also been reported to the ECDC, Europe's disease monitoring agency, by Iceland and Denmark. Media reports in Belgium say cases have also been detected there.
"It is right to take it seriously," said Peter Openshaw, a professor of experimental medicine at Imperial College London. Shaun Fitzgerald, a visiting professor at the University of Cambridge, said the situation was "extremely concerning."
The main worry is that the variant is significantly more transmissible than the original strain. It has 23 mutations in its genetic code - a relatively high number of changes - and some of these are affecting its ability to spread.
Scientists say it is about 40 percent-70 percent more transmissible. The UK government said on Saturday it could increase the reproduction "R" rate by 0.4.
This means it is spreading faster in Britain, making the pandemic there yet harder to control and increasing the risk it will also spread swiftly in other countries.
"The new B.1.1.7 ... still appears to have all the human lethality that the original had, but with an increased ability to transmit," said Martin Hibberd, professor of emerging infectious disease at the London School of Hygiene & Tropical Medicine.
Will COVID-19 vaccines protect against this variant?
Scientists say there's no evidence that vaccines currently being deployed in the UK - made by Pfizer and BioNtech - or other COVID-19 shots in development will not protect against this variant.
"It's unlikely that this will have anything more than a minor, if any, effect on the vaccine's effectiveness," said Adam Finn, a vaccine specialist and professor of pediatrics at Bristol University.
Britain's chief scientific adviser Patrick Vallance also said COVID-19 vaccines appeared to be adequate in generating an immune response to the variant of the coronavirus.
"We are not seeing...any gross changes in the spike protein that will reduce vaccine effectiveness so far," said Julian Tang, professor and clinical virologist at Leicester University.
Does the new variant affect testing?
To some extent, yes.
One of the mutations in the new variant affects one of three genomic targets used by some PCR tests. This means that in those tests, that target area, or "channel", would come up negative.
"This has affected the ability of some tests to detect the virus," said Robert Shorten, an expert in microbiology at the Association for Clinical Biochemistry & Laboratory Medicine.
Since PCR tests generally detect more than one gene target, however, a mutation in the spike protein only partly affects the test, reducing that risk of false negative results.
Are there other significant SARS-CoV-2 variants about?
Yes. Strains of the COVID-19-causing virus have emerged in recent months in South Africa, Spain, Denmark and other countries that have also raised concern.
However none, so far, has been found to contain mutations that make it more deadly, or more likely to be able to evade vaccines or treatments.
Did this new variant originate in Britain?
Vallance said on Saturday he thought the new variant might have started in the UK. Some scientists in Europe have credited British expertise in genomic surveillance for identifying the mutation.
"The UK has one of the most comprehensive genetic surveillance program in the world - 5 percent to 10 percent all virus samples are genetically tested. Few countries do better," Steven Van Gucht, head of viral diseases at the Belgian Institute of Health, told a news conference on Monday.