A vaccine-resistant Covid variant is an "absolute inevitability" and reaching herd immunity via the jabs rollout is impossible, top scientists have warned.
Sir Andrew Pollard, who chairs UK's vaccines watchdog the JCVI, told MPs on Tuesday that while jabs would "slow" transmission, the Delta variant, and other future strains, can still infect the double vaccinated.
The JCVI last week said people 16 and 17 should be offered at least one dose of the vaccine.
But Sir Andrew suggested vaccinating younger children would not help stop the spread entirely and the jabs programme should not be built around it.
He told a session of the All-Party Group on Coronavirus : “We know very clearly with coronavirus that this current variant, the Delta variant, will still infect people who have been vaccinated and that does mean that anyone who’s still unvaccinated, at some point, will meet the virus.”
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Sir Andrew predicted that the next thing may be “a variant which is perhaps even better at transmitting in vaccinated populations” as he suggested herd immunity was "mythical".
He added: “So, that’s even more of a reason not to be making a vaccine programme around herd immunity.”
It came as the number of coronavirus deaths in England and Wales climbed to its highest level since the end of March, with 404 deaths registered in the week ending July 30 - a 24% increase on the previous week.
Figures released by Public Health England last week also showed that around 35% of people in hospital with the virus (512) -had both doses of the vaccine, with the Delta strain currently accounting for around 99% of cases.
Professor Paul Hunter, from the University of East Anglia, meanwhile, said that variants which would escape vaccines were an “absolute inevitability”.
He said: “It is absolutely inevitable that we are going to get escape variants coming in.”
Prof Hunter said coronaviruses already in circulation will infect people “repeatedly” throughout their lives, typically on average every four or five years.
“Quarter of the UK population will get infected on average every year, what that means is about 45,000 people will be infected every day with these other coronaviruses.
“Ultimately what happened with these other coronaviruses is that although you get a gradual escape, because we are getting re-infected so frequently, we actually keep up.”
Prof Devi Sridhar, chair in global public health at the University of Edinburgh, said new strains of Covid would hit vaccines, adding: “We have already seen Alpha, Beta, Delta, it is inevitable.”
She added that vaccines had “transformed” the pandemic but “not solved it”.
Lib Dem MP Layla Moran, chair of the APPG on Coronavirus, said: “The worrying evidence we heard today suggests that given the emergence of new variants, including vaccine-resistant ones, achieving herd immunity is just a pipe dream.
"The government's plan to learn to live with Covid cannot become a byword for abdicating responsibility to the most vulnerable.
"Ministers must re-evaluate their approach and come up with a new and comprehensive, long-term plan to mitigate the risks posed by Covid and new variants."
Meanwhile, the Department for Health and Social Care announced that more than three-quarters of adults in the UK have now had both doses of a Covid vaccine.
A total of 86,780,455 doses have been administered in the UK, with 47,091,889 people receiving a first dose (89%) and 39,688,566 people receiving both doses (75%).
Boris Johnson said: “Our incredible vaccine rollout has now provided vital protection against the virus to three-quarters of all UK adults. This is a huge national achievement, which we should all be proud of.
“It’s so important that those who haven’t been vaccinated come forward as soon as possible to book their jab – to protect themselves, protect their loved ones and allow us all to enjoy our freedoms safely.”
Health Secretary Sajid Javid added: “Three in four adults across the UK have now had both doses of the vaccine, which is incredible and a testament to the fantastic work of the NHS, volunteers and everyone involved in the rollout.”
