Scientists have said a Covid-19 variant resistant to the current crop of vaccines is likely to emerge at some point, but immunisations can also be adapted “within weeks”.

The vaccines which have so far been rolled out to over half a million people in the UK provide immunity against the new more transmissible variant, but its emergence has raised questions about whether future mutations could conquer immunisations.

In mid-December, England’s chief medical officer Professor Chris Whitty said that as more people become vaccinated, the likelihood of a new variant which is partially able to escape the current jabs increases.

Professor Robert Dingwall, a member of The New and Emerging Respiratory Virus Threats Advisory Group (Nervtag) – which advises the Government, said: “I think that Professor Whitty is absolutely right, it is a question of when rather than if.

“It could happen tomorrow, it could happen in five years’ time. The mutations, the variations, are essentially random, and there’s no way to predict.

“I think the one thing that can be said is that the coronavirus appears to be more stable than the influenza virus.

“Where you do have to make new influenza virus vaccines every year because of the inherent instability of that virus, with the coronavirus it does seem that the process is probably much slower.

“And the existing immunity, whether it’s natural immunity because people have been infected with the previous strain, or immunity induced by the vaccination, should continue to recognise and respond to this variant, and we should not be worried that we have suddenly lost the capacity to treat it.”

Prof Dingwall, a leading medical sociologist who has researched genetics and evolution for decades, added he has seen reports showing that Pfizer and BioNTech could adapt their vaccines “within a matter of weeks”.

Virologist Professor Lawrence Young agreed the jabs could be modified in “up to six weeks” to tackle stronger mutant strains, and explained why an increase in vaccinations makes a resistant variant more likely to emerge.

When asked if this means the UK now faces a race between mutations and vaccine rollout, Prof Young said: “The frightening thing is, we don’t know that another mutation might pop up somewhere and scupper things.

“What we do know is, if we can stamp out transmission and get the vaccine out there you can stamp out the virus before you allow it to undergo more mutations – but it is a race, absolutely.”

Prof Young, who is also a molecular oncology expert at Warwick Medical School, added: “There is another issue here, which is what happens when you get a lot of people vaccinated.

“Because that could also drive mutations in the virus, because as the virus grows and more mutations occur, you could actually see a scenario whereby in the vaccinated population, that vaccine, and that immune response drives the selection of mutants that are not seen by the vaccine.

“So it is possible that you could end up with a situation where the current first generation vaccines won’t work because you’re driving further adaption of the virus.”

Dr Julian Tang, a clinical virologist at the University of Leicester, added the UK has “routine monitoring by viral sequencing for most vaccine preventable diseases” to ensure they can be modified accordingly.