Prime Minister Boris Johnson pushed back his plan to lift coronavirus restrictions by four weeks as a more infectious variant spreads rapidly across the U.K., threatening to undermine the country’s effort to vaccinate its way out of the pandemic.

The government in London was forced to act after modeling showed hospital admissions could reach similar levels to the first wave of infections in spring 2020 -- a peak of more than 3,000 a day -- if Johnson stuck to his schedule to end social-distancing rules on June 21. In a televised briefing on Monday, he said there was no choice but to delay his plan until July 19.

The aim is to prevent a surge in hospitalizations and avoid adding thousands to what’s already Europe’s highest death toll by allowing more people to get their second vaccine dose. Johnson said he is “pretty confident” there won’t be another postponement, while some members of his governing Conservative Party hit out at the impact on the economy.

“The objective of this short delay is to use these valuable, crucial weeks to save thousands of lives -- lives that would otherwise be lost, I’m afraid -- by vaccinating millions more people as fast as we can,” Johnson said.

Follow a Q&A live blog on the delta variant at 3 p.m. London time

While Britain gained global attention with its rapid vaccine rollout, the country is now emerging as the less enviable test case in Europe for dealing with the highly transmissible delta variant first identified in India. The World Health Organization’s Europe director, Hans Kluge, warned last week that delta was “poised to take hold” across the continent.

Vaccine Rethink

The issue for the U.K. is that its inoculation program lengthened the time between doses in an effort to get as many shots into as many people as quickly as possible. The new variant has changed the calculus after evidence emerged that two injections are required for protection. The government is now speeding up second shots.

The revised lockdown timetable is expected to go to a vote in the U.K. Parliament on Wednesday, and Johnson is likely to face anger from Conservative colleagues for backtracking on what they dubbed “Freedom Day.”

The government also said it will not extend financial support for businesses, despite the delay. A furlough program is due to run until the end of September, though employers will have to contribute more from July.

Not extending the financial assistance is “unjust, unconscionable and unsupportable,” Tory MP Bob Neill said in the House of Commons late Monday.

‘Small Impact’

Economists, however, said the the government’s decision will unlikely delay Britain’s recovery from the worst recession in 300 years.

“We doubt it will have a material impact on the trajectory of the economy,” said Dan Hanson of Bloomberg Economics. The delay would mean slower growth than previously estimated in the third quarter, but the economy would then recoup some of the lost ground in the following three months, he said.

Allan Monks, an economist at JPMorgan Chase & Co., echoed those sentiments, saying he expects the measures “to have a fairly small impact.” “Confidence and mobility have already recovered significantly even with the current restrictions in place,” he said in a report.

Conservative MP Mark Harper, who leads a group of lockdown-skeptic Conservatives, warned there would be an “inevitable rise” in the virus in the autumn and winter -- and asked Health Secretary Matt Hancock to rule out bringing back restrictions.

Hancock said a rise “isn’t inevitable” due to a planned vaccination booster program, though he added that eradicating the virus is impossible and that people must learn to live with it.

Variant Risk

Johnson had initially planned to drop all legal limits on social contact this month, in the final step of his “road map” out of lockdown. That would have meant nightclubs reopening, people lining up at the bar again, full stadiums and big conferences back in the diaries.

There was a reprieve for weddings: the 30-person limit will be lifted to allow an unlimited number of guests, as long as there is no dancing and social distancing is respected.

Covid cases have been rising rapidly. More than nine in 10 new cases in the U.K. are of the delta variant, according to Public Health England, and these infections are doubling every 4.5 days in parts of the nation.

Delta is 64% more transmissible indoors than the previously dominant alpha variant first identified in southeast England, PHE said, and early data show “a significantly increased risk of hospitalization.”

The government will review the data again on June 28, with the possibility of easing restrictions on July 5, though that’s considered unlikely. Right now, infections in England are growing 64% every week nationally, Johnson said. The key is whether positive cases lead to more people in intensive care and ultimately more deaths, or whether vaccines have broken that link enough.

Timely Pause

The month-long delay would give the government some “breathing space” to scrutinize the data, said Lawrence Young, a virologist at Warwick Medical School. Easing restrictions in late July when schools have closed for summer would also help contain virus spread, he said.

“If we push them back any further, that could result in crashing into the winter months, but I also don’t think the public are going to tolerate restrictions beyond that,” Young said. “We are going to have to get to a position where we have to live with the virus.”

In the meantime, all eyes are on the speed of vaccinations. Almost 80% of adults have received at least one dose, while 57% have gotten two. The government aims to fully vaccinate two-thirds of adults by July 19. All over-18s will be offered a first dose by then, too.

New analysis from PHE released on Monday found that two doses of Pfizer- BioNTech offer 96% protection against hospitalization, and 92% for the Oxford University- AstraZeneca shot.

The vaccines are “spectacularly more effective that we ever dared hope,” said Patrick Vallance, the government’s chief scientific adviser.

— With assistance by Joe Mayes, and Alaa Shahine