Covid cases in the UK are rising exponentially, largely in younger age groups who are more likely to be partially or completely unvaccinated. What does this mean for the risk of new variants popping up?

How do variants develop?

Once a person is infected, the virus that causes Covid-19 replicates tens of thousands of times within our cells. That process is imperfect, so occasionally mutations crop up – some of those changes are completely inert, but others could be more dangerous.

For a variant to take hold the environment needs to be favourable. The environment is dictated by a host of factors – including interventions such as masks, social distancing, ventilation, vaccines, and the number of immuno-compromised people in whom the vaccines don’t work as well. “That unbalance either favours or disfavours how a variant will spread,” says Dr Stephen Griffin, a virologist and associate professor at the University of Leeds school of medicine.

Does a high case rate increase the risk of variants?

The main thing that drives the evolution of a virus is its ability to transmit, scientists say. “So, if you do have a high case rate … by definition, more people are growing the virus in their bodies, then the more chances there are of the virus mutating and spreading,” noted Prof Lawrence Young, a virologist from the University of Warwick.

Although vaccines dramatically stem the likelihood of symptomatic disease, hospitalisation and death by weakening the ability of the virus to replicate within our bodies, it can still replicate to a certain extent, said Young, noting that there a few published cases of somewhat immuno-compromised individuals being infected and generating multiple variants.

“But this goes on in all of us all the time – and the more the virus spreads, the more it’s allowed to replicate in an uncontrolled way, the more of a chance of developing variants that will become not only more infectious, but also variants might pop up that can evade the [vaccine-induced] immune response.”

What’s the chance of a new variant that further evades vaccines popping up?

The existing vaccines protect against all known variants – but not 100%, because no vaccine can. But as a significant portion of the population is only partially vaccinated or unvaccinated alongside an exponential rise in cases, the virus has the opportunity to evolve and for new dangerous variants to take hold.

The risk of a variant completely evading vaccines is unlikely, say scientists, because the magnitude of protection the vaccines induce is broad so even if a particular mutation is particularly pathogenic, it is improbable that will render the vaccines redundant.

“I think the idea of a variant that is completely resistant to vaccines is very slim, said Young. “But we could still have a virus that is more able to evade some components of the immune system, especially in the most vulnerable and elderly population.”

By ‘learning to live with the virus’, do we risk turning countries into ‘variant factories’?

Scientists agree that there will come a time when we need to learn to live with Covid – but many argue that now may not be that time, given a high majority of a country is not yet fully vaccinated and cases are rising exponentially. If all restrictions including mask-wearing and social distancing are lifted in the coming weeks the likelihood of dangerous variants evolving and further eroding our vaccine shield will be enhanced, they say.

“If we’re moving into a situation where the idea that we vaccinated the most vulnerable and as many people as we can – let’s just let the virus continue to infect everybody else, including youngsters, that’s a very dangerous thing because if the virus is allowed to spread or replicate in an uncontrolled way more variants will be popping up all the time,” said Young.

“What we need to be doing now is stamping out infection. I’d be very much more comfortable if we had 80% of the population – I mean the whole population – completely protected by vaccination, because that would dampen things down.”

Griffin also added that long Covid is a “terrible thing”, especially in children.