The TLDR: A highly infectious mutation of the coronavirus may be rapidly spreading across the UK. Vast parts of the country are in total lockdown just in time for Christmas. And Britain has become a Covid pariah, as European nations moved swiftly to impose travel bans. We explain what this new mutation is—and assess how worried we should be. 

The basic deets

The spike: 

• The UK government describes the new strain as “out of control”—and says it is responsible for a huge spike in cases. 
• The average total jumped 40% in just one week. 
• According to the government’s chief scientific adviser, “It is becoming the dominant variant; it is beating all the others in terms of transmission.” 
• The mutation first appeared in mid-September when it caused 28% of the cases. It is now responsible for 60% of all new infections. 
• The UK is reporting roughly 24,061 new cases every day.

The lockdown: Boris Johnson basically canceled Christmas. London and South East England have been totally shut down. Wales and Scotland have gone into lockdown as well. Brits reacted to the news by rushing out the door to do their Christmas shopping—or cramming themselves into trains (clip here) to head home. And of course, funny memes ensued:

The travel ban: A still growing list of EU countries—from France to Bulgaria—have imposed a travel ban on the UK. Even Canada is now part of the list. Some are temporary, while others will last at least a few weeks. The reason for worry: infections from the new UK strain have been reported in Denmark and Australia and the Netherlands.

Point to note: A similar mutation has been reported in South Africa, as well—but the UK doesn’t seem to be the source of it.

Tell me about this mutation…

First, a definition: Viruses spread by replicating themselves at an astonishing speed. And like all living things, viruses are made up of protein molecules—which in turn are constructed of 20 types of amino acid. Think of them as Lego blocks. How you combine these amino acids determines what kind of protein you end up with. So when a virus produces a copy of itself, there are routine changes and sometimes ‘copying errors’—and that may cause changes in a protein molecule's behaviour. 

Point to note: The coronavirus has picked up an average of two mutations a month—around 25 since the beginning of the pandemic. The great majority of these have been minor. 

Even so, this latest mutation is worrying for three reasons:

One, number of alterations: A routine mutation entails a handful of changes in the genetic material. In this case, there are 23 in total, and 17 of these are “potentially important.” A preliminary report put out by researchers calls this “unprecedented in the global virus genomic data for the COVID-19 pandemic.”

Point to note: The sheer number of alterations also point to a likely source of the new strain: Someone with a compromised immune system who suffered a chronic Covid infection. And here’s why:

“These patients are unable to fight off their infection, meaning SARS-CoV-2 has time to survive in their bodies and mutate. Like a living laboratory for its evolution. What's more, in places like the UK, immune-compromised patients are treated with convalescent plasma donated by Covid-19 survivors, chock full of antibodies against the virus. If these therapies fail, they don't just fail the patient—they allow the virus inside them to adapt mutations to avoid those antibodies.”

Two, more infectious, maybe: In his press conference, Boris Johnson said that the new strain is “70% more transmissible”—which in turn means one person can potentially infect more people. But this early assessment is based solely on correlation: There are a higher number of cases in locations where the strain is more prevalent. BBC News offers the following caveat:

“It is a warning sign, although it can be interpreted in two ways. The virus could have mutated to spread more easily and is causing more infections. But variants can also get a lucky break by infecting the right people at the right time.”

For example, a previous mutation from Spain that emerged in June was thought to be more infectious. But in fact, it was simply opportunistic—taking advantage of young Europeans celebrating the end of lockdown and travel bans. 

Point to note: Despite the uncertainty, experts agree it is far wiser to err on the side of caution than wait for weeks or months for results of lab experiments.

Three, the location: Let’s circle back to the Lego block analogy. When this strain was created, some amino acids were either deleted or added during replication. The result is at least two changes in the protein molecules on the spikes of the coronavirus. This spike protein helps the virus hook on to the surface of a cell, dissolve its coating and enter. Any change here could potentially make it easier for the virus to infect human cells—and harder to fight off an infection. The two key alterations are:

• The mutation N501 is located on the most important part of the spike—where it first makes contact with the surface of our cells. Experts say: "It looks and smells like an important adaptation.”
• The other mutation—the H69/V70 deletion—has been seen before in infected minks. One of the findings in that case: Antibodies triggered by previous strains were not very effective in fighting off this new one. So it was as though your body was encountering an entirely new virus. 

Point to note: Each of these significant mutations have been seen separately in other strains of the virus—but never all together in one virus. 

Ugh, is there any good news here?

Yes, there is very good news on two key points. One, there is no evidence that this mutation causes a more severe disease, more hospitalizations or “more trouble than the other virus.” Two, scientists are fairly confident that it will not affect the efficacy of the leading vaccines. 

Why is that?

There is no doubt that the latest mutation is significant. Experts admit that the virus could be on the path toward “vaccine escape”—which is when a virus adapts to avoid being killed by a vaccine. But that’s still fine and here’s why:

• Vaccines train the immune system to attack several different parts of the virus. So changes in the spike shouldn’t render them ineffective.
• Even if one strain dodges an existing vaccine, they are fairly easy to tweak. They will just have to be regularly updated much like the flu vaccine.

Reading list

You can read the original report written by UK researchers. BBC News has the two best pieces on the new strain—an overview and a closer look on its infectiousness. The Wire has a very good analysis of the mutation that emerged in minks. The Conversation has an excellent—and very readable—explanation of how mutations work.