Hello, and welcome back to i’s science newsletter. With concerns rising in some quarters about the new Covid variant, XEC, I’m taking a look at why new forms of this virus keep appearing, and whether they are anything to worry about.
The XEC variant was first noticed in Germany in June, and according to a public database of coronavirus sequences, is now causing about a fifth of Covid infections in the UK, with claims it may drive the next wave this winter.
For some, the arrival of XEC may be alarming. But many Covid experts are not worried.
“You’ll always find people who claim Armageddon is coming with every new variant,” said Professor Paul Hunter, a microbiologist at the University of East Anglia. “Covid is going up and down, sometimes driven by new variants, sometimes for other reasons.”
Where do the new forms of the coronavirus come from, and why are there such different opinions about how we should respond?
Contagious
XEC is just the latest in a long line of new Covid variants (see graph, below). Any new variant that becomes dominant certainly is more contagious – but that’s unsurprising as the fact that it is better at passing between people is probably the very reason it has overtaken the previous variants. “It spreads more by definition,” said Professor Hunter.
The new variants arise because all viruses are constantly mutating as they multiply within your body. Most mutations will be damaging or useless.
Just occasionally, though, a mutation will give a virus an advantage – in terms of being able to spread more easily through the body, or spread between people – and so it takes over. “This happens for all respiratory viruses – it’s nothing new,” said Professor Hunter.
In 2024, the key factor slowing the spread of Covid viruses is widespread immunity, arising from previous infections or vaccination.
The term immunity does not mean that people can never be infected with Covid again – as is clear from the numbers who have had test-confirmed infections twice, or three, four times or more.
Milder illness
For most people, a previous brush with Covid or being vaccinated means that they can still get infected – especially as time goes on – but they are much less likely to get seriously ill from it, and need hospital treatment.
That’s because there are many different components of the immune system. Antibodies, a branch of the immune system that is important for preventing infections, do tend to wane over time. But memory T-cells, a component that is key for stopping the viral infection from progressing to serious illness, tend to persist for much longer.
How much should we be worrying each time a new Covid variant becomes dominant? A successful new variant can (sometimes, but not always) drive a rise in cases.
I recently argued here, that it is time for people to stop scaremongering and catastrophising whenever there is another wave of Covid. Official NHS advice is that we should behave around Covid the same way we do around other respiratory illness, such as cold and flu.
Having said that, I completely understand that for some people who are clinically vulnerable – whose immune systems may be weaker – it can be alarming when Covid rates are high, and I sympathise with those wanting to take more precautions as a result, such as wearing face masks.
But for others, a new variant is not necessarily any more dangerous to an individual who catches it than one of the previous variants.
In fact, the more recent variants may be intrinsically less dangerous. Studies have shown that when the coronavirus first arrived in the UK, it had an infection fatality rate of about 1 per cent – about 20 times more than that for flu. This has since dropped to a rate quite similar to flu, probably from a combination of immunity and a fall in intrinsic virulence.
Mutations
The XEC variant is classed as being in the large Omicron family of Covid viruses, which first reached the UK at the end of 2021, and there is no evidence that XEC is any worse than the other forms of Omicron.
And there’s no reason to think XEC would be especially dangerous based on its mutations, said Professor Francois Balloux, director of University College London’s Genetics Institute. “It’s not got that many more new mutations compared with what else we are seeing. I feel a bit surprised that it’s attracting so much attention.”
It could be instructive to look back at some of the previous Covid variants from the graph above, and consider what actually happened in the population. The alarmingly named “Kraken” variant, for instance, did not lead to a surge in deaths or hospitalisations from Covid in 2023, when it was dominant.
Other things I’ve written recently
In the BBC comedy, Gavin and Stacey, when Alison Steadman’s character Pam tries out a “low-carb” diet, she serves herself a dinner of three steaks – with the two extra ones replacing her usual chips and peas.
The sketch may have been a caricature of low-carbing, but some people seem to be following Pam’s lead, with food-focused social media sites currently awash with advocates of the “carnivore diet”.
This way of eating breaks all the rules in the medical textbooks – so what effects does it have on the body and why are people doing it? Read more here.
I’m watching
This weekend I’ll be visiting New Scientist Live, a public science festival held at the Excel Centre in London. I’ll admit that I’m biased, because before coming to i, I used to write for New Scientist. But as well as catching up with my old workmates, I’ll be listening to talks on everything from black holes, to volcanoes, to how neuroscience can get to grips with free will. You can see the full programme here.
