The UK will not be able to keep borders shut forever and a “sustainable strategy” will be needed in the future to tackle coronavirus mutations, a senior Government scientific adviser has said.

Andrew Hayward, professor of infectious disease epidemiology at University College London (UCL) and a member of the Scientific Advisory Group for Emergencies (Sage), said that while it was sensible to try to stamp out chains of transmission of variants – as is happening across parts of England now – new strains will continue to be a risk.

It comes as scientists said a few samples of the Kent variant of coronavirus that has been rapidly spreading across the UK contain the same worrying mutation – E484K – as seen in the South Africa and Brazil variants.

Public Health England (PHE) has suggested that although vaccines may work less well against this mutation, they will still be effective in preventing severe disease.

The discovery of the South Africa strain of coronavirus has prompted a series of travel bans, with people arriving into England from anywhere outside the UK, Ireland, the Channel Islands or the Isle of Man needing to isolate at home for 10 days and providing a negative Covid-19 test result before they travel.

A system of quarantine is due to be introduced in the coming weeks that will require those arriving from countries under travel bans to isolate in hotels.

Labour has urged the Government to go further and bring in a hotel quarantine system for all UK arrivals as a way of keeping out mutant strains.

But Prof Hayward said more attention needed to be paid to the “endgame” as variants will pose an ongoing risk.

Asked on Sky News about the probability of more strains entering the UK unless borders are shut completely, or unless all people entering the country are forced into hotel quarantine for 14 days, Prof Hayward said: “Well, probably in the long term, 100%.

“The nature of this virus is that it will continue to mutate, as do all viruses, and new strains will emerge and they’ll emerge in many different countries in the world at different times, and you won’t notice that they are spreading until such time as they are quite widespread.

“The real challenge here is that, well, yes, you can think about completely shutting the borders or having quarantine, (but) what’s the endgame in that?

“Is that something that you’re going to do forever, because it looks like these strains may continue to arise in the long term?

“So we need some sort of sustainable strategy, and I think that’s very difficult for politicians to think about that.”

He said at the moment scientists did not fully understand the potential of the new strains, though vaccines were still expected to be “very worthwhile” and keeping cases of the new strain low would assist their rollout.

But he said the 11 cases of the South African variant identified in eight different parts of England were only the “tip of the iceberg”.

There is the scientific perfect answer, and then there’s the answer that policymakers will come to, which is sort of practical and achievable

He added: “This variant is identified through genetic sequencing and we sequence between 5% and 10% of all cases, so you can immediately tell from that that we have a big under-estimation of the number of cases.”

He said the 11 could be multiplied “by quite a high level”, adding: “We would expect we’re seeing the tip of the iceberg of community transmission.”

Elsewhere, Professor Sir Mark Walport, former chief scientific adviser to the Government, said it was “almost impossible” to completely shut down the country and prevent highly transmissible new strains.

Asked about border closures, Sir Mark told Times Radio: “There is the scientific perfect answer, and then there’s the answer that policymakers will come to, which is sort of practical and achievable.

“The simple answer is, if you want to stop new variants coming to the country then you have to do everything you can to reduce travellers and isolate them as they come across the border.

“The challenge for a country like the UK, which is a major global hub where for our resilience we depend on supplies from all over the world, is whether it’s practical to actually achieve that.

“I think, realistically, most people would feel that, whilst one can delay the coming in of new variants of viruses from around the world, it’s almost impossible to completely close down a country and prevent that happening if there is a very highly transmissible variant.”

Sir Mark suggested testing local communities when there were flare-ups of new variants would be needed, saying: “I think it has to be a viable option for the future. The virus isn’t going to go away.”

Professor Calum Semple, a member of Sage, said it was important to try to “snuff out” the South African variant, especially while the population is being vaccinated, but said mutations can arise spontaneously within individual countries.

On the issue of borders, he said that while it is important to restrict the movement of people as much as possible, it is not practical to close the UK’s borders completely.

“You can’t do it altogether when you have got a country that is dependent on imports for food and other essential processes. It is just not possible,” he said.

Meanwhile, universities minister Michelle Donelan said hotel quarantine for all countries – reportedly something which might be announced in Scotland – would be “unfeasible”.

She told BBC Breakfast: “We have to be realistic about what we adopt and what we do, and what is deliverable as well, and also targeted in our approach to making sure that we minimise the risk and identifying those countries where we can see the risk.

“So, a blanket policy that Nicola Sturgeon is proposing would not necessarily be as effective as the one that we are suggesting, and also it’s much more doable.”

Ms Donelan also rejected suggestions that the Government should have moved to close the borders to stop new variants reaching the UK.

“The Sage advice actually said that it would be probably ineffective to close the borders, which was the same advice that we got at the time from the World Health Organisation,” she said.

It comes as around 80,000 people in England are being targeted for testing to find cases of the South Africa variant.

Eleven cases of the variant identified over the past week were in people who had no links to international travel, prompting concerns the mutation has spread in communities.

PHE is studying whether those who have already had the vaccine could need a booster shot in the future to help protect them against Covid-19 mutations.