More transmissible than other strains, it may require stricter lockdowns.
Viruses are the fashionistas of the microbe world. They change their appearance constantly but such changes are usually small, transient and of little practical significance for how they spread or how deadly they are.
SARS-CoV-2, the COVID-19 virus, has so far been no exception, according to The Economist.
But a new variant of it that is spreading rapidly in Britain appears to buck the trend. According to researchers advising the British government, it may be 40-70% more transmissible than the other variants in circulation. Britain has alerted the World Health Organisation about this variant, provisionally called VUI 202012/01 (short for the first "variant under investigation" in December 2020).
The authorities are rushing to limit its spread. Swathes of Britain where VUI 202012/01 is most prevalent, including London, went into lockdown in the early hours of December 20th. By the evening, Belgium, France, Germany, the Netherlands and Italy had banned flights from Britain. Other countries are sure to follow suit. The port of Dover was closed to outbound lorries and ferry passengers after France closed its border for 48 hours on the evening of the 20th.
Read alsoEU to discuss response to new COVID-19 variant as travel bans on UK expand
It is not yet clear whether VUI 202012/01 causes symptoms that are different or of different severity from those induced by its cousins. Studies to answer that question are under way in Britain. Researchers are also looking for additional evidence that this variant is more contagious – and what biological mechanisms may be at play.
Two factors suggest greater contagiousness. First, it has spread much faster than other variants in parts of Britain where infections have been rising unusually rapidly. It accounted for 62% of new infections in London in the week ending December 9th, up from 28% in early November.
The second red flag is the particular combination of mutations and other tweaks in its genome – 23, which experts say is an unusually large number given how the virus has changed so far. More worrying, laboratory and animal studies have found that several of these changes make the virus better at infecting cells, at making more copies of itself once it enters those cells, and at evading antibodies made by the immune system during infection with other variants.
Read alsoCOVID-19: Expert says new mutant strain already in Ukraine
The big worry for now is whether VUI 202012/01 is, indeed, a lot more contagious than other variants. If the current estimates from Britain's preliminary data are confirmed, it can increase by 0.4 or more the virus's reproductive number (known as R), which is the average number of people who catch the virus from an infected individual.
"This will mean that far stricter measures would be needed to slow down the spread of COVID-19 wherever this variant lands. The urgent attempts to contain its spread are therefore warranted. How much it can be slowed down until vaccines start to make a difference is an open question," reads the report.