Several countries have started to close their doors to travellers from the United Kingdom amid concerns about a rapidly spreading strain of Covid-19 that has caused cases to soar there.

A woman wears a face mask as she steps out of Bank underground station, in London, December 8, 2020
A woman wears a face mask as she steps out of Bank underground station, in London, December 8, 2020 (AP)

Reports from Britain and South Africa of new coronavirus strains that seem to spread more easily are causing alarm but virus experts say it’s unclear if that’s the case or whether they pose any concern for vaccines or cause more severe disease.

Virus evolution is natural and expected

Viruses naturally evolve as they move through the population, some more than others. It’s one reason we need a fresh flu shot each year.

New variants, or strains, of the virus that causes Covid-19 have been seen almost since it was first detected in China nearly a year ago.

On Saturday, Prime Minister Boris Johnson announced new restrictions because of the new strain.

Several European Union countries, South American nations and Canada have banned or limited some flights from the UK to try to limit any spread. More are expected to follow.

READ MORE: UK PM to hold emergency meeting amid growing crisis over new virus strain

Here’s what is known about the mutation.

What's worrying about the UK strain? 

Health experts in the UK and US said the strain seems to infect more easily than others, but there is no evidence yet that it is more deadly.

Patrick Vallance, the British government’s chief scientific adviser, said that the strain “moves fast and is becoming the dominant variant,” causing over 60 percent of infections in London by December.

The strain is also concerning because it has so many mutations – nearly two dozen – and some are on the spike protein that the virus uses to attach to and infect cells. That spike is what current vaccines target.

“I’m worried about this, for sure,” but it’s too soon to know how important it ultimately will prove to be, said Dr Ravi Gupta, who studies viruses at the University of Cambridge in England. He and other researchers posted a report of it on a website scientists use to quickly share developments, but the paper has not been formally reviewed or published in a journal.

READ MORE: UK: New Covid-19 strain spreading rapidly

How do new strains occur? 

Viruses often acquire small changes of a letter or two in their genetic alphabet just through normal evolution. A slightly modified strain can become the most common one in a country or region just because that’s the strain that first took hold there or because “super spreader” events helped it become entrenched.

A bigger worry is when a virus mutates by changing the proteins on its surface to help it escape from drugs or the immune system.

“Emerging evidence” suggests that may be starting to happen with the new coronavirus, Trevor Bedford, a biologist and genetics expert at the Fred Hutchinson Cancer Research Center in Seattle, wrote on Twitter.

“We’ve now seen the emergence and spread of several variants” that suggests this, and some show resistance to antibody treatments, he noted.

Are there other strains? 

In April, researchers in Sweden found a virus with two genetic changes that seemed to make it roughly two times more infectious, Gupta said. About 6,000 cases worldwide have been reported, mostly in Denmark and England, he said.

Several variations of that strain now have turned up.

Some were reported in people who got them from mink farms in Denmark. A new South African strain has the two changes seen before, plus some others.

The one in the UK has the two changes and more, including eight to the spike protein, Gupta said. It’s called a “variant under investigation” because its significance is not yet known.

Scientists first discovered the new variant in a patient in September. And Public Health England notified the government on Friday when modelling revealed the full seriousness of the new strain.

Will it affect vaccines? 

Probably not, former US Food and Drug Commissioner Scott Gottlieb said Sunday on CBS’s “Face the Nation.”

“Unlikely,” Gupta agreed.

US President-elect Joe Biden’s surgeon general nominee, Vivek Murthy, said Sunday on NBC’s “Meet the Press" that there's “no reason to believe that the vaccines that have been developed will not be effective against this virus as well.”

Vaccines produce wide-ranging responses by the immune system beyond just those to the spike protein, several experts noted.

The possibility that new strains will be resistant to existing vaccines are low, but not “inexistent,” Dr Moncef Slaoui, the chief science adviser for the US government’s vaccine distribution effort, said Sunday on CNN’s “State of the Union.”

“Up to now, I don’t think there has been a single variant that would be resistant,” he said. “This particular variant in the UK, I think, is very unlikely to have escaped the vaccine immunity.”

Bedford agreed.

“I’m not concerned” because a lot of changes in the genetic code would probably be needed to undermine a vaccine, not just one or two mutations, Bedford wrote on Twitter.

But vaccines may need fine-tuning over time as changes accumulate, and changes should be more closely monitored, Bedford wrote.

Murthy said the new strain doesn’t change the public health advice to wear masks, wash hands and maintain social distance.

The novel coronavirus has killed almost 1.7 million people since the outbreak emerged in China last December, according to tracking meters. 

And with the onset of colder winter weather in the northern hemisphere where respiratory diseases flourish, countries are bracing for new waves of Covid-19 with tighter restrictions, despite the economic damage such lockdowns wrought earlier this year.

Source: TRTWorld and agencies