Boris Johnson will hold a Downing Street press conference on Monday at 6pm, No.10 has confirmed, where he is expected to announce a delay to the lifting of coronavirus rules in England.
The prime minister will be joined by Chris Whitty, the chief medical officer and Patrick Vallance, the chief scientific adviser.
Johnson is set to announce the ending of social-distancing rules – which had been slated for June 21 – will be delayed for four weeks to July 19.
The move follows warnings from scientists that the rapid spread of the Delta variant first identified in India risks a third wave if it is allowed to spread unchecked.
Health minister Edward Argar said that if the June 21 lockdown easing were to be delayed for one month, another 10 million second coronavirus vaccine doses would go into arms in this time.
“If we are going at a run rate of about 250,000 to 300,000 second jabs being done each day, a month gives you roughly that 10 million, which closes the gap,” he told BBC Breakfast on Monday morning.
He also did not rule out shortening the gap between coronavirus vaccine doses for younger adults.
Professor Devi Sridhar, from the University of Edinburgh, said a third wave of cases largely in younger age groups was already happening “but the worry is that this will slowly move, like it has in previous waves, into older groups”, some of whom are not yet fully protected.
She told BBC Radio 4’s Today programme the goal was to “make this a manageable health issue” and use vaccines and testing to “keep the burden off health services”.
But reports that the June 21 date will be missed have already triggered a backlash from some Tory MPs, who said there was no reason not to end the restrictions as those most at risk of death or serious illness are now fully vaccinated.
Mark Harper, the chairman of the Covid Recovery Group (CRG), said any postponement would be a “political choice”.
He warned that if the unlocking did not go ahead as planned, restrictions could carry on through the autumn and into the winter as other respiratory infections picked up.
“The effectiveness of our vaccines at preventing hospitalisation means unlocking on June 21 could proceed safely. Any decision to delay will be a political choice,” he said.
“Variants and mutations will appear for the rest of time. We have to learn to live with it. If our very effective vaccines cannot deliver us freedom from restrictions, then nothing ever will.”
Steve Baker, the CRG deputy chairman, questioned how long the country could “fumble along” with restrictions that had such “devastating consequences” for both business and people’s mental health.