A computer image created by Nexu Science Communication together with Trinity College in Dublin, shows a model structurally representative of a betacoronavirus which is the type of virus linked to COVID-19. Photo: NEXU Science Communication

While the government was planning to ease restrictions on June 21, Johnson announced the U.K. will push back reopenings until July 19 at the latest, amid rising infections and hospitalizations tied to the variant. The additional weeks are hoped to give the National Health Service (NHS) more time to deliver jabs into arms.

"We’ve obviously faced a difficult choice," Johnson said during a press conference. "We can simply keep going with all of step 4 on June 21st, even though there is a real possibility that the virus will outrun the vaccines and thousands more deaths would ensue that could otherwise have been avoided. Or else, we can give the NHS a few more crucial weeks to get those remaining jabs into the arms of those who need them."

Cases are growing by 64% each week, doubling in the worst affected areas, while the average number of people admitted to the hospital in England is increasing by 50% week over week, climbing to 61% in the northwest, he said. The government's lockdown response plan defines step 4 as eliminating "all legal limits on social contact" and reopening "remaining premises, including nightclubs, and easing the restrictions on large events and performances." Those restrictions will remain in place, with the exception of weddings with over 30 guests where social distancing is in place, among other events.

"Since today I cannot say that we have met all our four tests for proceeding with step 4 on June the 21st, I think it is sensible to wait just a little longer," he said, noting that the U.K. is aiming to fully vaccinate about two-thirds of the adult population by July 19, including everyone over age 50, all the vulnerable, frontline workers and everyone 40 and up who received initial doses by mid-May. Officials also aim to see every adult with an initial dose by July 19 to lower the risk of transmission.

"As things stand and on the evidence that I can see right now, I’m confident that we will not need more than four weeks and we won't need to go beyond July the 19th," Johnson said.

Officials will monitor the situation daily, and if after two weeks, it's determined that the risk has diminished, the U.K. could see a full reopening sooner.