Boris Johnson has repeatedly declined to say how many people are expected to have to self-isolate following the final relaxation of COVID restrictions in England on 19 July.
Labour leader Sir Keir Starmer accused the prime minister of putting the country on course for a “summer of chaos and confusion” as he noted Health Secretary Sajid Javid’s admission that there could be 100,000 coronavirus cases a day within weeks.
Sir Keir highlighted estimations that such an infection rate could see millions of Britons a week being forced to self-isolate this summer as COVID levels soar.
The prime minister is facing a backlash after he unveiled a plan to move to the fourth and final stage of his roadmap for lifting COVID restrictions on 19 July.
However, an exemption from 10-day self-isolation for double-jabbed adults, or under-18s, who have been a contact of an infected person will not be introduced until 16 August.
Businesses have warned of the economic harm of large numbers of workers having to quarantine over the next few weeks.
Quizzing Mr Johnson during Wednesday’s session of Prime Minister’s Questions, Sir Keir said: “Let’s be clear why infection rates are so high – because the prime minister let the Delta – or we can call it the ‘Johnson variant’ – into the country.
“Let’s be clear why the number of cases will surge so quickly – because he is taking all protections off in one go. That is reckless.”
The Labour leader added the “massive” number of people set to be self-isolating this summer would mean “huge disruption to families and businesses just as the summer holidays begin”.
“It won’t feel like ‘freedom day’ to those who have to isolate, when they’re having to cancel their holidays, when they can’t go to the pub or even to their kid’s sports day,” he said.
“And it won’t feel like freedom day to the businesses who are already warning of carnage because of the loss of staff and customers.”
It was “entirely predictable” that people had begun deleting the NHS contact-tracing app – in order to avoid being “pinged” and having to self-isolate – Sir Keir told the prime minister.
“They’re doing it because they can see what’s coming down the track,” he said. “Now of course we don’t support that, but under his plan it’s entirely predictable.”
Mr Johnson said the government was taking a “prudent approach” by “moving away from self-isolation towards testing over the course of the next few weeks”.
But he repeatedly refused to say how many people he expects to be self-isolating this summer, or how many deaths, hospitalisations and cases of long COVID he thought might occur after the relaxation of restriction on 19 July.
He said: “There are a number of projections and they’re available from the Spi-M graphs, but what’s certainly true is that we’re seeing a wave of cases because of the Delta variant.
“But scientists are also absolutely clear that we have severed the link between infection and serious disease and death.
“Currently there are only a 30th of the deaths that we were seeing at an equivalent position in previous waves of this pandemic.”
On more than one occasion, the prime minister challenged Sir Keir to set out whether or not he supported the lifting of almost all remaining COVID restrictions on 19 July.
The Labour leader said: “We should open up in a controlled way, keeping baseline protections such as masks on public transport, improving ventilation, making sure the Track and Trace system remains effective, and ensuring proper payments for self-isolation.”
On Monday, the government’s chief scientific adviser Sir Patrick Vallance said that COVID vaccines had “weakened the link between cases and hospitalisations”, but warned it was “a weakened link, not a completely broken link”.